Home Current Issue Previous Issues Podcasts Online First ASA Practice Parameters CME For Authors Journal Info
Skip Navigation LinksHome > March 2009 - Volume 110 - Issue 3 > Practice Advisory on Anesthetic Care for Magnetic Resonance...
Anesthesiology:
doi: 10.1097/ALN.0b013e31818f9206
Special Articles

Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging: A Report by the American Society of Anesthesiologists Task Force on Anesthetic Care for Magnetic Resonance Imaging*

Free Access
Supplemental Author Material
Article Outline
Collapse Box

Author Information

PRACTICE advisories are systematically developed reports that are intended to assist decision making in areas of patient care. Advisories are based on a synthesis of scientific literature and analysis of expert and practitioner opinion, clinical feasibility data, open forum commentary, and consensus surveys. Advisories developed by the American Society of Anesthesiologists (ASA) are not intended as standards, guidelines, or absolute requirements. They may be adopted, modified, or rejected according to clinical needs and constraints.
The use of practice advisories cannot guarantee any specific outcome. Practice advisories summarize the state of the literature, and report opinions obtained from expert consultants and ASA members. Practice advisories are not supported by scientific literature to the same degree as standards or guidelines because of the lack of sufficient numbers of adequately controlled studies. Practice advisories are subject to periodic revision as warranted by the evolution of medical knowledge, technology, and practice.
The magnetic resonance imaging (MRI) suite is a hazardous location because of the presence of a strong static magnetic field, high-frequency electromagnetic (radiofrequency) waves, and a time-varied (pulsed) magnetic field. Secondary dangers of these energy sources include high-level acoustic noise, systemic and localized heating, and accidental projectiles. There may be significant challenges to anesthetic administration and monitoring capabilities due to static and dynamic magnetic fields as well as radiofrequency energy emissions. Direct patient observation may be compromised by noise, darkened environment, obstructed line of sight, and other characteristics unique to this environment (e.g., distractions). Unlike a conventional operating room, the MRI environment frequently requires the anesthesiologist to assume broader responsibility for immediate patient care decisions.
Back to Top | Article Outline

Methodology

A. Definition of Anesthetic Care for MRI and High-risk Imaging
This Advisory defines anesthetic care for MRI as moderate sedation, deep sedation, monitored anesthesia care, general anesthesia, or ventilatory and critical care support. High-risk imaging refers to imaging in patients with medical or health-related risks; imaging with equipment-related risks; and procedure-related risks, such as MRI-guided surgery, minimally invasive procedures (e.g., focused ultrasound, radiofrequency ablation), or cardiac and airway imaging studies.
Back to Top | Article Outline
B. Purpose
The purposes of this Advisory are to (1) promote patient and staff safety in the MRI environment, (2) prevent the occurrence of MRI-associated accidents, (3) promote optimal patient management and reduce adverse patient outcomes associated with MRI, (4) identify potential equipment-related hazards in the MRI environment, (5) identify limitations of physiologic monitoring capabilities in the MRI environment, and (6) identify potential health hazards (e.g., high decibel levels) of the MRI environment.
Back to Top | Article Outline
C. Focus
This Advisory focuses on MRI settings where anesthetic care is provided, specifically facilities that are designated as level II or III (appendix 1). Level II refers to facilities that image patients requiring monitoring or life support. Level III refers to facilities that are designed for operative procedures. This Advisory does not apply to level I facilities, where no anesthetic care is provided.
Table 1
Table 1
Image Tools
Four zones within the MRI suite have been identified, with ascending designations indicating increased hazard areas.1,2 These areas within the MRI suite are categorized as zones I–IV (table 1).
Back to Top | Article Outline
D. Application
This Advisory is intended for use by anesthesiologists or other individuals working under the supervision of an anesthesiologist, and applies to anesthetic care performed, supervised, or medically directed by anesthesiologists, or to moderate sedation care supervised by other physicians. Because the safe conduct of MRI procedures requires close collaboration and prompt coordination between anesthesiologists, radiologists, MRI technologists, and nurses, some responsibilities are shared among the disciplines. When shared responsibilities are described in this Advisory, the intent is to give the anesthesiologist a starting point for participating in the allocation and understanding of shared responsibilities. The Advisory may also serve as a resource for other physicians and healthcare professionals (e.g., technologists, nurses, safety officers, hospital administrators, biomedical engineers, and industry representatives).
This Advisory does not address specific anesthetic drug choices and does not apply to patients who receive minimal sedation (anxiolysis) to complete the scan or procedure safely and comfortably.
Back to Top | Article Outline
E. Task Force Members and Consultants
The ASA appointed a Task Force of 13 members. These individuals included 10 anesthesiologists in private and academic practice from various geographic areas of the United States, 1 radiologist, and 2 consulting methodologists from the ASA Committee on Standards and Practice Parameters.
The Task Force developed the Advisory by means of a seven-step process. First, they reached consensus on the criteria for evidence. Second, a systematic review and evaluation was performed on original published research studies from peer-reviewed journals relevant to MRI safety. Third, a panel of expert consultants was asked to (1) participate in opinion surveys on the effectiveness of various MRI safety strategies and (2) review and comment on a draft of the Advisory developed by the Task Force. Fourth, opinions about the Advisory were solicited from a random sample of active members of the ASA. Fifth, the Task Force held an open forum at two major national meetings to solicit input on its draft recommendations. Sixth, the consultants were surveyed to assess their opinions on the feasibility of implementing this Advisory. Seventh, all available information was used to build consensus within the Task Force to create the final document, as summarized in appendix 2.
Back to Top | Article Outline
F. Availability and Strength of Evidence
Preparation of this Advisory followed a rigorous methodologic process (appendix 3). Evidence was obtained from two principal sources: scientific evidence and opinion-based evidence.
Back to Top | Article Outline
Scientific Evidence.
Study findings from published scientific literature were aggregated and are reported in summary form by evidence category, as described below. All literature (e.g., randomized controlled trials, observational studies, case reports) relevant to each topic was considered when evaluating the findings. For reporting purposes in this document, the highest level of evidence (i.e., level 1, 2, or 3 identified below) within each category (i.e., A, B, or C) is indicated in the summary.
Back to Top | Article Outline
Category A: Supportive Literature.
Randomized controlled trials report statistically significant (P < 0.01) differences among clinical interventions for a specified clinical outcome.
Back to Top | Article Outline
Level 1:
The literature contains multiple randomized controlled trials, and the aggregated findings are supported by meta-analysis.
Back to Top | Article Outline
Level 2:
The literature contains multiple randomized controlled trials, but there is an insufficient number of studies to conduct a viable meta-analysis for the purpose of this Advisory.
Back to Top | Article Outline
Level 3:
The literature contains a single randomized controlled trial.
Back to Top | Article Outline
Category B: Suggestive Literature.
Information from observational studies permits inference of beneficial or harmful relations among clinical interventions and clinical outcomes.
Back to Top | Article Outline
Level 1:
The literature contains observational comparisons (e.g., cohort, case–control research designs) of two or more clinical interventions or conditions and indicates statistically significant differences between clinical interventions for a specified clinical outcome.
Back to Top | Article Outline
Level 2:
The literature contains noncomparative observational studies with associative (e.g., relative risk, correlation) or descriptive statistics.
Back to Top | Article Outline
Level 3:
The literature contains case reports.
Back to Top | Article Outline
Category C: Equivocal Literature.
The literature cannot determine whether there are beneficial or harmful relations among clinical interventions and clinical outcomes.
Back to Top | Article Outline
Level 1:
Meta-analysis did not find significant differences among groups or conditions.
Back to Top | Article Outline
Level 2:
There is an insufficient number of studies to conduct meta-analysis and (1) randomized controlled trials have not found significant differences among groups or conditions or (2) randomized controlled trials report inconsistent findings.
Back to Top | Article Outline
Level 3:
Observational studies report inconsistent findings or do not permit inference of beneficial or harmful relations.
Back to Top | Article Outline
Category D: Insufficient Evidence from Literature.
The lack of scientific evidence in the literature is described by the following terms.
Back to Top | Article Outline
Silent:
No identified studies address the specified relations among interventions and outcomes.
Back to Top | Article Outline
Inadequate:
The available literature cannot be used to assess relations among clinical interventions and clinical outcomes. The literature either does not meet the criteria for content as defined in the “Focus” of the Advisory or does not permit a clear interpretation of findings because of methodologic concerns (e.g., confounding in study design or implementation).
Back to Top | Article Outline
Opinion-based Evidence.
All opinion-based evidence relevant to each topic (e.g., survey data, open-forum testimony, Internet-based comments, letters, editorials) is considered in the development of this Advisory. However, only the findings obtained from formal surveys are reported.
Opinion surveys were developed by the Task Force to address each clinical intervention identified in the document. Identical surveys were distributed to two groups of respondents: expert consultants and ASA members.
Back to Top | Article Outline
Category A: Expert Opinion.
Table 2
Table 2
Image Tools
Table 2
Table 2
Image Tools
Table 2
Table 2
Image Tools
Survey responses from Task Force–appointed expert consultants are reported in summary form in the text. A complete listing of consultant survey responses is reported in table 2 in appendix 3.
Back to Top | Article Outline
Category B: Membership Opinion.
Table 3
Table 3
Image Tools
Table 3
Table 3
Image Tools
Table 3
Table 3
Image Tools
Survey responses from a random sample of members of the ASA are reported in summary form in the text. A complete listing of ASA member survey responses is reported in table 3 in appendix 3.
Survey responses are recorded using a 5-point scale and summarized based on median values.§
Strongly agree: median score of 5 (at least 50% of the responses are 5)
Agree: median score of 4 (at least 50% of the responses are 4 or 4 and 5)
Equivocal: median score of 3 (at least 50% of the responses are 3, or no other response category or combination of similar categories contain at least 50% of the responses)
Disagree: median score of 2 (at least 50% of the responses are 2 or 1 and 2)
Strongly disagree: median score of 1 (at least 50% of the responses are 1)
Back to Top | Article Outline
Category C: Informal Opinion.
Open-forum testimony, Internet-based comments, letters, and editorials are all informally evaluated and discussed during the development of the Advisory. When warranted, the Task Force may add educational information or cautionary notes based on this information.
Back to Top | Article Outline

Advisories

I. Education
MRI safety education includes, but is not limited to, topics addressing: (1) MRI magnet hazards in zones III and IV, (2) challenges and limitations of monitoring, and (3) long-term health hazards.
There is insufficient published evidence to evaluate the effect of education regarding magnet hazards, monitoring limitations, or long-term health hazards associated with MRI. [Category D evidence] One observational study examined the potential long-term health hazards of pregnant MRI workers and pregnant non-MRI workers, and found no significant difference in the relative risk of early delivery, low birth weight, or spontaneous abortions.3 [Category C evidence]
The consultants and ASA members strongly agree that all anesthesiologists should have general safety education on the unique physical environment of the MRI scanner. The ASA members agree and the consultants strongly agree that all anesthesiologists should have specific education regarding the features of individual scanners within their institution. The ASA members agree and the consultants strongly agree that anesthesiologists should work in collaboration with radiologists, technologists, and physicists within their institutions to develop safety training programs.
Back to Top | Article Outline
Advisory Statements.
All anesthesiologists should have general safety education on the unique physical environment of the MRI scanner and specific education regarding the specific features of individual scanners within their institution. Education should emphasize safety for entering zones III and IV, with special emphasis on hazards in this environment and effects on monitoring capabilities. Education should address potential health hazards (e.g., high decibel levels and high-intensity magnetic fields) and necessary precautions to deal with the specific field strength and the safety of the MRI scanners within their institutions. Education should include information regarding ferromagnetic items (e.g., stethoscopes, pens, wallets, watches, hair clips, name tags, pagers, cell phones, credit cards, batteries) and implantable devices (e.g., spinal cord stimulators, implanted objects) that should not be brought into zone III or IV of the MRI suite or should be brought in with caution. Anesthesiologists should work in collaboration with radiologists, technologists, and physicists within their institutions to ensure that the above topics are included in their safety training programs. Finally, education should include how to safely respond to code blue situations in zones III and IV, and this information should be integrated into protocols for the designated code blue team.
Back to Top | Article Outline
II. Screening of Anesthetic Care Providers and Ancillary Support Personnel
The MRI medical director or designated technologist is responsible for access to zones III and IV. Screening of all individuals entering zone III is necessary to prevent accidental incursions of ferromagnetic materials or inadvertent exposure of personnel with foreign bodies or implanted ferromagnetic items.
The literature is silent regarding whether the screening of anesthesia care providers and ancillary support personnel improves safety in the MRI suite. [Category D evidence] The ASA members agree and the consultants strongly agree that the anesthesiologist should work in collaboration with the MRI medical director or designee to ensure that all anesthesia team personnel entering zone III or IV have been properly screened.
Back to Top | Article Outline
Advisory Statements.
The anesthesiologist should work in collaboration with the MRI medical director or designee (e.g., safety officer) to ensure that all anesthesia team personnel entering zone III or IV have been screened for the presence of ferromagnetic materials, foreign bodies, or implanted devices.
Back to Top | Article Outline
III. Patient Screening
Patient screening consists of determining patient and equipment-related risks for adverse outcomes associated with MRI procedures.
Patient-related Risks: Risks related to the patient may include age-related risks, health-related risks, and risks from foreign bodies located in or on the patient or implanted ferromagnetic items. Age-related risks apply to neonates or premature infants, and elderly patients. Health-related risks include, but are not limited to, (1) the need for intensive or critical care; (2) impaired respiratory function (e.g., tonsillar hypertrophy, sleep apnea); (3) changes in level of sedation, muscle relaxation, or ventilation; (4) hemodynamic instability and vasoactive infusion requirements; and (5) comorbidities that may contribute to adverse MRI effects (e.g., burns or temperature increases in patients with obesity or peripheral vascular disease). Risks from foreign bodies include nonmedical ferromagnetic items imbedded in the patient (e.g., eyeliner tattoos, metallic intraocular fragments) or attached to the patient (e.g., pierced jewelry, magnetic dental keepers). Risk from implanted ferromagnetic items may include such items as aneurysm clips, prosthetic heart valves, or coronary arterial stents.
One comparative study reports that neonates undergoing MRI demonstrate increased fluctuations in heart rate, blood pressure, and oxygen saturation levels compared with neonates not undergoing MRI.4 [Category B1 evidence] Two observational studies report that premature neonates can experience heart rate fluctuations, decreases in oxygen saturation, and increases in temperature during MRI.5,6 [Category B2 evidence] One case report indicates that a child with a history of previous cardiac arrest experienced a cardiac arrest during MRI.7 [Category B3 evidence] Four observational studies8–11 and two case reports12,13 indicate that patients with impaired renal function are at risk of nephrogenic systemic fibrosis after gadolinium administered for MRI. [Category B2 evidence]
Case reports indicate that exposure of iron filings to the magnetic field may result in hemorrhage,7,14 and exposure of eyeliner tattoos may result in image artifacts, burns, swelling, or puffiness.7,15–17 [Category B3 evidence] Numerous observational studies and case reports indicate interactions with the magnetic field (e.g., movements, displacements, image artifacts) and increases in temperature during MRI for ferromagnetic items such as aneurysm clips, surgical clips, prosthetic heart valves, intravenous infusion pumps, coronary arterial stents, and implanted dental magnet keepers.18–43 [Category B2 evidence]
Both the consultants and the ASA members strongly agree that, for every case, the anesthesiologist should communicate with the patient and radiologist or referring physician to determine whether the patient has a high-risk medical condition. In addition, they both strongly agree that if the patient presents with a high-risk medical condition, the anesthesiologist should collaborate with all participants, including the referring physician, radiologist, and technologist, to determine how the patient will be managed during the MRI procedure. Both the consultants and the ASA members agree that, for patients with acute or severe renal insufficiency, the anesthesiologist should not administer gadolinium because of the increased risk of nephrogenic systemic fibrosis.
Equipment-related Risks: Patient equipment-related risks include, but are not limited to, (1) physiologic monitors; (2) invasive monitors (e.g., intravascular catheters); (3) intubation equipment; (4) oxygenation and ventilation equipment; and (5) pacemakers, implanted cardiodefibrillators, and other implanted devices (e.g., deep brain stimulators, vagal or phrenic nerve stimulators, middle-ear or cochlear implants).
One case report notes that cardiac monitor leads interfered with an MRI scan.7 [Category B3 evidence] One observational study and one case report indicate that fire or burns occurred beneath or near cardiac monitor electrodes.44,45 [Category B2 evidence] Five case reports note that burns occurred from the looping of a temperature probe or pulse oximetry cables.46–50 [Category B3 evidence] One observational study reports ferromagnetic components in ventilators51 [category B2 evidence], and three case reports describe projectile nitrous oxide or oxygen tanks52–54 [category B3 evidence]. Additional observational studies and case reports indicate interactions of pacemakers or implanted cardioverter–defibrillators with MRI scanning, including, but not limited to, pacing artifacts, reed switch closure, generator movement or displacement, alterations of pacing rate, and temperature increases.7,55–84 [Category B2 evidence] Two observational studies report palpitations, rapid heart rate, and discomfort at the pacemaker pocket after MRI.75,85 [Category B2 evidence] Finally, two cases of cardiac arrest are reported in patients with pacemakers during or after an MRI scan; in one case, the patient died.7,57 [Category B3 evidence]
Two observational studies report image artifacts when MRI is performed in patients with neurostimulators, infusion pumps, or implantable spinal fusion stimulators.86,87 Six observational studies report increased temperatures in patients with deep brain stimulators, neurostimulators, or spinal cord stimulators,88–93 and three report displacement of leads, pulse generators, or other components of deep brain stimulators or middle ear prostheses during MRI scans.94–96 [Category B2 evidence]
Both the consultants and the ASA members agree that, for every case, the anesthesiologist should communicate with the radiologist or referring physician to determine whether the patient requires equipment that may pose a risk during the scan. In addition, they agree that anesthesiologists should determine the safety and effectiveness of the equipment needed by the patient during the procedure for each MRI location. Further, the consultants and ASA members strongly agree that anesthesiologists should work with their institutions to properly identify and label anesthesia-related equipment according to convention for each MRI scanner. The ASA members agree and the consultants strongly agree that care should be taken to ensure that anesthesia equipment does not interfere with image acquisition or quality. Both the consultants and the ASA members agree that, in general, MRI should not be performed on patients with implanted electronic devices. Finally, both the consultants and the ASA members strongly agree that, when MRI is considered essential by the referring physician and consulting radiologist, a plan for managing patients with implanted electronic devices during the scan should be developed in collaboration with the referring physician, medical director or on-site radiologist, and other appropriate consultants.
Back to Top | Article Outline
Advisory Statements for Patient and Equipment-related Risks.
For every case, the anesthesiologist should communicate with the patient, referring physician, and radiologist to determine whether the patient (1) presents with a high-risk medical condition (e.g., neonatal status or prematurity, intensive or critical care status, impaired respiratory function, hemodynamic instability and vasoactive infusion requirements, comorbidities such as obesity and peripheral vascular disease); (2) requires equipment (e.g., physiologic or invasive monitors; intubation, oxygenation, or ventilation equipment); (3) has implanted devices (e.g., pacemakers, cardioverter–defibrillators, nerve stimulators); (4) has been screened for the presence of implanted ferromagnetic items (e.g., surgical clips, prosthetic heart valves); and (5) has been screened for the presence of imbedded foreign bodies (e.g., orbital iron filings, eyeliner tattoos). Finally, the anesthesiologist should communicate with the technologist to ensure that the patient has been screened for the presence of foreign bodies on the patient (e.g., pierced jewelry, rings) before entering zone III.
If a patient presents with a high-risk medical condition, the anesthesiologist should collaborate with all participants, including the referring physician, radiologist, and technologist, to determine how the patient will be managed during the MRI procedure. Anticipated changes in level of sedation, muscle relaxation, or ventilation may also place a patient in a high-risk situation.
For patients with acute or severe renal insufficiency, the anesthesiologist should not administer gadolinium because of the increased risk of nephrogenic systemic fibrosis.
Anesthesiologists should work with their institutions to properly identify and label anesthesia-related equipment according to convention (safe, unsafe, or conditional) for each MRI scanner.# For each MRI location, anesthesiologists should determine the safety and effectiveness of the equipment needed by the patient during the procedure. In addition, care should be taken to ensure that equipment does not interfere with image acquisition or quality.
The Task Force believes that cardiac pacemakers and implantable cardioverter–defibrillators are generally contraindicated for MRI. These devices pose an extreme hazard in this environment and may be life-threatening within the 5 gauss line. When MRI is considered essential by the referring physician and consulting radiologist, a plan for managing these patients during the scan should be developed in collaboration with the ordering physician, medical director or on-site radiologist, and other appropriate consultants (e.g., the patient's pacemaker specialist or cardiologist, the diagnostic radiologist, the device manufacturer).**
Other implanted electronic devices also pose a hazard in the MRI environment. These devices and associated wiring may transfer energy during the MRI scan, causing tissue damage, malfunction of the device, image artifacts, and device displacement. MRI may be performed on a limited basis for patients with certain implanted electronic devices (e.g., deep brain stimulators, vagal nerve stimulators, phrenic nerve stimulators, wire-containing thermodilution catheters, cochlear implants). In consultation with the referring physician, the radiologist responsible for the procedure, and the neurosurgeon, the anesthesiologist should ensure that the presence of the device has been noted and determined to be MRI safe/conditional before imaging of these patients.
Back to Top | Article Outline
IV. Preparation
Preparation consists of determining and implementing an individualized anesthetic plan before the MRI procedure begins. In addition to the anesthetic plan, preparation includes a plan for optimal positioning of equipment and personnel in the MRI suite during the procedure.
The literature is insufficient to determine whether active preparation or pre-MRI planning reduces the frequency of adverse events. [Category D evidence] One case report indicates that misinformation about the type of aneurysm clip resulted in intracerebral hemorrhage and death,31 and a second case report indicates that a lack of communication among physicians caring for a pacemaker patient resulted in the death of the patient.97 [Category B3 evidence]
Both the consultants and the ASA members strongly agree that, for every case, the anesthesiologist should prepare, with support personnel, a plan for providing optimal anesthetic care within the special environment of the MRI suite. They both strongly agree that the anesthesiologist should communicate with the radiology personnel to determine the requirements of the scan. The ASA members agree and the consultants strongly agree that the anesthesiologist should collaborate with the magnetic resonance (MR) technologist and/or facility biomedical engineer to determine and demarcate the optimal and safe location of movable equipment in relation to the gauss lines within the MRI suite. They both strongly agree that, because line of sight within the bore will vary depending on the facility, the anesthesiologist should choose a location or position for optimal patient observation and vigilance during delivery of care, whether in zone III or IV. Finally, they both strongly agree that the anesthesiologist should prepare a plan for rapidly summoning additional personnel in the event of an emergency.
Back to Top | Article Outline
Advisory Statements.
For every case, the anesthesiologist should prepare, with support personnel, a plan for providing optimal anesthetic care within the special environment of the MRI suite. In addition to addressing the medical needs of the patient, features of the plan should include (1) requirements of the scan and personnel needs, (2) positioning of equipment, (3) special requirements or unique issues of patient or imaging study, (4) positioning of the anesthesiologist and the patient, and (5) planning for emergencies.
1. The anesthesiologist should communicate with the radiology personnel to determine the requirements for the scan (e.g., duration of the scan, position of the patient or area of the body in the scanner, positioning of receiver coils, need for periods of paused respiration). The anesthesiologist should communicate with other anesthesia team members regarding individual roles for anesthetic care.
2. The anesthesiologist should collaborate with the MR technologist and/or facility biomedical engineer to determine and demarcate the optimal and safe location of movable equipment in relation to the gauss lines within the MRI suite.
3. Because line of sight within the bore will vary depending on the facility, the anesthesiologist should choose a location or position for optimal patient observation and vigilance during delivery of care, whether in zone III or IV. In particular, anesthesiologists should have (1) a clear line of sight of the patient and physiologic monitors, whether by direct observation or by video camera; (2) anesthetic delivery equipment located for optimal control of anesthetic depth and rapid intervention; and (3) access to hospital information systems integral to patient care. In preparing for positioning, the anesthesiologist should take into account potential electromagnetic and auditory hazards.
4. Anesthesiologists should prepare a plan for rapidly summoning additional personnel in the event of an emergency. Because the MRI suite is frequently located in an isolated area of the facility, the anesthesiologist should ensure that (1) emergency equipment and drugs are immediately accessible; (2) emergency communication (e.g., phone or code button) is immediately available; and (3) an evacuation plan is in place, including an appropriate location outside the scan room (zone IV) for resuscitation. This location should be complete with physiologic monitors, oxygen, suction, and other appropriate resuscitation equipment. Monitoring requirements, airway management, and emergency preparedness are additional features that should be included in the preparation and planning for an MRI scan, and are addressed in section V below.
Back to Top | Article Outline
V. Patient Management during MRI
Features of safe patient management during MRI procedures include (1) monitoring, (2) anesthetic care, (3) airway management, and (4) management of emergencies.
Back to Top | Article Outline
Monitoring.
Safe monitoring conditions include (1) the use of MRI-safe/conditional monitors, (2) remote monitoring, and (3) compliance with ASA standards.98
Three observational studies indicate that the use of MRI-compatible monitoring equipment resulted in no radiofrequency interference, interruptions in scanning, or artifacts.99–101 [Category B2 evidence] Five observational studies demonstrate that remote monitoring for heart rate, blood pressure, auscultation, respiration, and chest wall movement can be performed safely and effectively.100,102–105 [Category B2 evidence] One observational study reported that compliance with the ASA Standards for Basic Anesthetic Monitoring can be obtained, provided that the monitoring equipment is properly tested before MRI.106 [Category B2 evidence]
The consultants and ASA members both strongly agree that MRI patients should be monitored in a manner consistent with the ASA Standards for Basic Anesthetic Monitoring. In addition, they both strongly agree that (1) anesthesiologists should be familiar with the expected limitations of available monitoring equipment, (2) the anesthesiologist should make sure that all monitors used in zone IV are safe/conditional for the scan, and (3) a monitor should be available to view vital signs from zone III when the anesthesia care provider is not in zone IV.
Back to Top | Article Outline
Advisory Statements.
MRI patients should be monitored in a manner consistent with the ASA Standards for Basic Anesthetic Monitoring. Anesthesiologists should be familiar with the expected limitations of available monitoring equipment. The Task Force notes that information from electrocardiograms may be limited because of superimposed voltages from blood flow in the high magnetic field (e.g., ST-segment interpretation may be unreliable, even with highly filtered monitors). The anesthesiologist should make sure that all monitors used in zone IV are safe/conditional for the scan. A monitor should be available to view vital signs from zone III when the anesthesia care provider is not in zone IV. Additional care should be taken in positioning electrocardiographic and other monitor leads to eliminate burns, even with nonferromagnetic leads.
Back to Top | Article Outline
Anesthetic Care.
Observational studies report a high rate of success in imaging of sedated patients or patients to whom light anesthesia is administered.107–112 However, motion artifacts may still occur.113–115 [Category B2 evidence] Observational studies and case reports also indicate that sedation or light anesthesia may be associated with respiratory depression, oxygen desaturation, bronchospasm, drowsiness, agitation, and vomiting.99,108–113,116–128 [Category B2 evidence] The Task Force believes that automated apnea monitoring (by detection of exhaled carbon dioxide or other means) may decrease risks during both moderate and deep sedation.
Both the consultants and the ASA members strongly agree that, in general, because MRI is a nonpainful procedure, lighter levels of anesthesia may be appropriate, recognizing that institutional circumstances, patient characteristics, and anesthesiologist preference may warrant more aggressive airway management and deeper anesthetic levels. They both strongly agree that anesthesiologists should ensure that patients who receive moderate or deep sedation are monitored in a manner consistent with their institution's protocol for monitoring similarly sedated patients elsewhere in the facility. In addition, they both strongly agree that equipment and drugs for anesthetic care in the MRI suite should mirror what is available in the operating room. Both the consultants and the ASA members are equivocal that, when an MRI-safe/conditional anesthesia machine is not available, inhalation anesthetics may be administered from an anesthesia machine inside zone III via an elongated circuit through a wave guide. Finally, both the consultants and the ASA members agree that, if total intravenous anesthesia is used, it should be administered by using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e., MRI-unsafe) pumps in zone III with intravenous tubing passed through a wave guide, or (3) periodic bolus injections in zone III or IV.
Back to Top | Article Outline
Advisory Statements.
Although lighter levels of anesthesia may be appropriate during an MRI scan, the anesthesiologist should be aware that these lighter levels may result in airway complications (e.g., laryngospasm, coughing, other airway compromise) that may necessitate interruption of the scan for urgent treatment and alteration of anesthetic depth. Institutional circumstances, patient characteristics, and anesthesiologist preference may warrant more aggressive airway management and deeper anesthetic levels.
Anesthesiologists should ensure that patients who receive moderate or deep sedation are monitored in a manner consistent with their institution's protocol for monitoring similarly sedated patients elsewhere in the facility. Monitoring of exhaled carbon dioxide should be considered for all patients receiving deep sedation and for patients whose ventilation cannot be directly observed during moderate sedation.†† The Task Force cautions that, because ventilation and oxygenation are separate though related physiologic processes, monitoring oxygenation by pulse oximetry is not a substitute for monitoring ventilatory function.
Equipment and drugs for anesthetic care in the MRI suite should mirror what is available in other anesthetizing locations, including (1) an integrated anesthesia machine, medical gases, and waste anesthesia gas disposal or gas scavenging, when inhalational anesthesia is administered; (2) suction; (3) adequate electrical outlets and lighting; and (4) storage areas for equipment and drugs. The Task Force recognizes that physical plant variability exists among institutions.‡‡ Equipment used in the MRI suite should be appropriate for the age and size of the patient.
Magnetic resonance imaging–safe/conditional anesthesia machines are always preferred for use in an MRI facility.§§ However, when an MRI-safe/conditional anesthesia machine is not available, inhalational anesthetics can be administered from an anesthesia machine inside zone III via an elongated circuit through a wave guide.∥∥ Although this method of anesthetic delivery was commonplace before the commercial manufacture of MRI-safe/conditional anesthesia machines, this practice is inherently cumbersome and may be prone to more possibilities for mishaps than the use of an anesthesia machine specifically designed for the MRI environment.
Alternatively, if total intravenous anesthesia is used, it should be administered by using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e., MRI unsafe) pumps in zone III with intravenous tubing passed through a wave guide, or (3) periodic bolus injections in zone III or IV. Although an anesthesia machine may not be required for the administration of total intravenous anesthesia, there must be equipment immediately available for the administration of positive-pressure ventilation with oxygen.
Back to Top | Article Outline
Airway Management.
Unique features of airway management during an MRI scan include (1) the limited accessibility of the patient's airway and (2) the difficulty of conducting visual and auditory assessments of the patient. The literature is silent regarding the management of airway problems (e.g., obstruction, secretions, laryngospasm, apnea and hypoventilation) during an MR scan. [Category D evidence] In addition, the literature is silent regarding whether the use of an endotracheal tube or laryngeal mask airway improves outcomes for patients at risk of airway compromise during MRI. [Category D evidence]
Both the consultants and the ASA members strongly agree that the anesthesiologist should have an advance plan in place to deal with instrumentation of the airway and common airway problems when patients are in an MRI environment. Both the consultants and the ASA members strongly agree that, if the patient is at risk for airway compromise, more aggressive airway management should be instituted because the patient's airway may be less accessible when the patient is in the scanner. Both the consultants and the ASA members strongly agree that (1) complex airway management (e.g., fiberoptic intubation) should be performed in a controlled environment outside of zone IV, (2) alternative airway devices should be immediately available in the MRI suite, and (3) suction equipment should be immediately accessible to the patient's airway at all times.
Back to Top | Article Outline
Advisory Statements.
The anesthesiologist should have an advance plan in place to deal with instrumentation of the airway and common airway problems (e.g., obstruction, secretions, laryngospasm, apnea and hypoventilation) when patients are in an MRI environment. If the patient is at risk for airway compromise, more aggressive airway management (e.g., use of a endotracheal tube or laryngeal mask airway) should be instituted because the patient's airway may be less accessible when the patient is in the scanner. Complex airway management (e.g., fiberoptic intubation) should be performed in a controlled environment outside of zone IV.
Alternative MRI-safe/conditional airway devices should be immediately available in the MRI suite. Suction equipment should be immediately accessible to the patient's airway at all times.
Back to Top | Article Outline
Management of Emergencies.
Emergencies in the MR suite include (1) medical emergencies (e.g., cardiopulmonary arrest) and (2) environmental emergencies (e.g., quench, fire, projectiles). The remote location of the scanner within the facility may delay response of support personnel or availability of equipment during an emergency.
The literature is insufficient regarding the management of medical emergencies (e.g., cardiopulmonary arrest) or quench in the MR suite. [Category D evidence] One case report indicates that a fire occurring on the patient was managed by extinguishing the flames, discontinuing the scan, and immediately removing the patient from the bore.45 Two case reports of projectile nitrous oxide or oxygen tanks indicate that the emergency was managed by removing patients from zone IV and instituting a controlled quench.53,54 [Category B3 evidence]
Both the consultants and the ASA members strongly agree that when a patient has a medical emergency in the MRI scanner, the following should occur: (1) initiate cardiopulmonary resuscitation, when needed, while immediately removing the patient from zone IV; (2) call for help; and (3) transport the patient to a previously designated safe location in proximity to the MRI suite. In addition, they both strongly agree that the designated safe location should contain the following resuscitation equipment: (1) a defibrillator; (2) vital signs monitors; and (3) a code cart that includes resuscitation drugs, airway equipment, oxygen, and suction. The consultants and ASA members both strongly agree that when a fire occurs in the MRI suite, team members should perform their preassigned fire management tasks as quickly as possible, in accordance with the ASA Practice Advisory for the Prevention and Management of Operating Room Fires.129 The ASA members agree and the consultants strongly agree that, when a quench occurs, team members should perform their institution's protocol in reaction to this occurrence. In addition, the ASA members agree and the consultants strongly agree that, when a quench occurs, if possible, (1) the patient should be removed from zone IV immediately and (2) oxygen should be administered to the patient immediately. Finally, both the consultants and the ASA members agree that, because powerful static magnetic fields may persist after a quench or fire, emergency response personnel should be restricted from entering zone IV.
Back to Top | Article Outline
Advisory Statements.
Medical emergencies may be difficult to manage while the patient is in the MRI scanner. When a patient has a medical emergency (e.g., cardiopulmonary arrest) in the MRI scanner, the following should occur: (1) immediately remove the patient from zone IV while initiating cardiopulmonary resuscitation, if indicated; (2) call for help; and (3) transport the patient to a previously designated safe area for resuscitation that is not in zone IV. This location should be as close to zone IV as possible so as not to delay resuscitation efforts, and should contain the following resuscitation equipment: a defibrillator; vital signs monitors; and a code cart that includes resuscitation drugs, airway equipment, oxygen, and suction.
When a fire occurs in the MRI suite, team members should perform their preassigned fire management task as quickly as possible, in accordance with the ASA Practice Advisory for the Prevention and Management of Operating Room Fires. If a team member cannot rapidly perform his or her task in the predetermined order, other team members should perform their tasks without waiting. When a team member has completed a preassigned task, he or she should help other members perform tasks that are not yet complete.
In the case of projectile emergencies, team members should perform their institution's protocol in reaction to this occurrence. If possible, immediately remove the patient from zone IV and discontinue the scan. If the patient is injured, proceed with medical emergency management as indicated above. A controlled quench may be necessary to remove the patient from the bore.
A quench occurs when a superconducting magnet turns resistive and catastrophically releases all of the stored energy as heat, boiling off the stored cryogens as gas. The most common cause of quench is an intentional shutdown of the magnet for a life-threatening emergency. Quench may also be the consequence of an unintentional shutdown. If not properly vented, a quench can result in the complete dissipation of oxygen in zone IV, risking hypoxia to the patient and MRI personnel. In addition, entrance to zone IV may not be possible because of high pressure caused by escaping gases, making it impossible to open the door into zone IV. When a quench occurs, team members should perform their institution's protocol in reaction to this occurrence. If possible, (1) immediately remove the patient from zone IV and (2) immediately administer oxygen to the patient.
Powerful static magnetic fields may persist after a quench, and therefore the usual precautions apply when entering zone IV. Emergency response personnel should be restricted from entering zone IV during any environmental emergency because of the persistent magnetic field.
Back to Top | Article Outline
VI. Postprocedure Care
The literature is insufficient to determine whether postprocedure care consistent with that provided for other areas of the institution reduces the frequency of adverse events. [Category D evidence]
The ASA members agree and the consultants strongly agree that the anesthesiologist should collaborate with the radiologist and other staff in the postanesthetic care of the patient. Finally, both the consultants and the ASA members strongly agree that (1) patients receiving sedation or anesthesia within the MRI suite should have access to postanesthetic care consistent with that provided in other areas of the institution; (2) in all situations, intensive care and recovery areas should include access to vital signs monitors, oxygen, suction, and trained personnel; and (3) patients should be given written discharge instructions.
Back to Top | Article Outline
Advisory Statements.
The anesthesiologist should collaborate with the radiologist and other staff in the postanesthetic care of the patient. Patients receiving sedation or anesthesia within the MRI suite should have access to postanesthetic care consistent with that provided in other areas of the institution,130 including transport to other recovery rooms, dedicated intensive care, or recovery areas within the MRI suite. In all situations, intensive care and recovery areas should include access to vital sign monitors, oxygen, suction, resuscitation equipment, and trained personnel.## Patients should be given oral and written discharge instructions.
Back to Top | Article Outline

References

1. Kanal E, Borgstede JP, Barkovich AJ, Bell C, Bradley WG, Felmlee JP, Froelich JW, Kaminski EM, Keeler EK, Lester JW, Scoumis EA, Zaremba LA, Zinninger MD: American College of Radiology white paper on MR safety. AJR Am J Roentgenol 2002; 178:1335–47

2. Kanal E, Barkovich AJ, Bell C, Bradler WG Jr, Froelich JW, Gilk T, Gimbel JR, Gosbee J, Kuhie-Kaminski E, Lester JW Jr, Nuenhuis J, Parag Y, Schaefer DJ, Sebek-Scoumis EA, Weinreb J, Zaremba LA, Wilcox P, Lucey L, Sass N, ACR Blue Ribbon Panel on MR Safety: ACR guidance document for safe MR practices: 2007. AJR Am J Roentgenol 2007; 188:1447–74

3. Kanal E, Gillen J, Evans JA, Savitz DA, Shellock FG: Survey of reproductive health among female MR workers. Radiology 1993; 187:395–9

4. Philbin MK, Taber KH, Hayman LA: Preliminary report: Changes in vital signs of term newborns during MR. AJNR Am J Neuroradiol 1996; 17:1033–6

5. Battin M, Maalouf EF, Counsell S, Herligy A, Hall A, Azzopardi D, Edwards AD: Physiologic stability of preterm infants during magnetic resonance imaging. Early Hum Dev 1998; 52:101–10

6. Taber KH, Hayman LA, Northrup SR, Maturi L: Vital sign changes during infant magnetic resonance examinations. J Magn Reson Imaging 1998; 8:1252–6

7. Gangarosa RE, Minnis JE, Nobbe J, Praschan D, Genberg RW: Operational safety issues in MRI. Magn Reson Imaging 1987; 5:287–92

8. Broome DR, Girguis MS, Baron PW, Cottrell AC, Kjellin I, Kirk GA: Gadodiamide-associated nephrogenic systemic fibrosis: Why radiologists should be concerned. AJR Am J Roentgenol 2007; 188:586–92

9. Grobner T: Gadolinium: A specific trigger for the development of nephrogenic fibrosing dermopathy and nephrogenic systemic fibrosis? Nephrol Dial Transplant 2006; 21:1104–8

10. Khurana A, Runge VM, Narayanan M, Greene JF Jr, Nickel AE: Nephrogenic systemic fibrosis: A review of 6 cases temporally related to gadodiamide injection. Invest Radiol 2007; 42:139–45

11. Marckmann P, Skov L, Rossen K, Dupont A, Damholt MB, Heaf JG, Thomsen HS: Nephrogenic systemic fibrosis: Suspected etiological role of gadodiomide used for contrast-enhanced magnetic resonance imaging. J Am Soc Nephrol 2006; 17:2359–62

12. Dharnidharka VR, Wesson SK, Fennel RS: Gadolinium and nephrogenic fibrosing dermopathy in pediatric patients. Pediatr Nephrol 2006; 22:1395

13. Thakral C, Alhariri J, Abraham JL: Long-term retention of gadolinium in tissues from nephrogenic systemic fibrosis patient after multiple gadolinium-enhanced MRI scans: Case report and implications. Contrast Media Mol Imaging 2007; 2:199–205

14. Kelly WM, Paglen PG, Pearson JA, San Diego AG, Soloman MR: Ferromagnetism of intraocular foreign body causes unilateral blindness after MR study. AJNR Am J Neuroradiol 1986; 7:243–5

15. Jackson JG, Acker JD: Permanent eyeliner and MR imaging. AJR Am J Roentgenol 1987; 49:1080

16. Lund G, Nelson JD, Wirtschafter JD, Williams PA: Tattooing of eyelids: Magnetic resonance imaging artifacts. Ophthalmol Surg 1986; 17:550–3

17. Wagle WA, Smith M: Tattoo-induced skin burn during MR imaging. AJR Am J Roentgenol 2000; 174:1795

18. Applebaum E, Valvassori G: Further studies on the effects of magnetic resonance fields on middle ear implants. Ann Otol Rhinol Laryngol 1990; 99:801–4

19. Barrafato D, Henkelman RM: Magnetic resonance imaging and surgical clips. Can J Surg 1984; 27:509–12

20. Becker RL, Forfray JF, Teitelbaum GP, Bradley WG Jr, Jacobs JB, Wacaser L, Rieman RL: MR imaging in patient with intracranial aneurysm clips. AJNR Am J Neuroradiol 1988; 9:885–9

21. Brown MA, Carden JA, Coleman RE, McKinney R, Spicer LD: Magnetic field effects on surgical ligation clips. Magn Reson Imaging 1987; 5:443–53

22. Chou C-K, McDougall JA, Chan KW: RF heating of implanted spinal fusion stimulator during magnetic resonance imaging. IEEE Trans Biomed Eng 1997; 44:367–72

23. Davis PL, Crooks L, Arakawa M, McRii R, Kaufman L, Margulis AR: Potential hazards of NMR imaging: Heating effects of changing magnetic fields and RF fields on small metallic implants. AJR Am J Roentgenol 1981; 137:857–60

24. Dujovny M, Kossovsky N, Kossowsky R, Valdivia R, Suk JS, Diaz FG, Berman K, Cleary W: Aneurysm clip motion during magnetic resonance imaging: In vivo experimental study with metallurgical factor analysis. Neurosurgery 1985; 17:543–8

25. Edwards MB, Taylor KM, Shellock FG: Prosthetic heart valves: Evaluation of magnetic field interaction, heating and artifacts at 1.5 T. J Magn Reson Imaging 2000; 12:363–9

26. Gegauff AF, Laurell KA, Thavendrarajah A, Rosenstiel SF: A potential MRI hazard: Forces on dental magnet keepers. J Oral Rehabil 1990; 17:403–10

27. Hartnell GG, Spence L, Hughe LA, Cohen MC, Saouf R, Buff B: Safety of MR imaging in patients who have retained metallic materials after cardiac surgery. Am J Roentgenol 1997; 168:1157–9

28. Hug J, Nagel E, Bornstedt A, Schnackenburg B, Oswald H, Fleck E: Coronary arterial stents: Safety and artifacts during MR imaging. Radiology 2000; 216:781–7

29. Kaste S, Laningham F, Stazzone M, Brown SD, Emery K, Newman B, Racadio J, Estroff J, Brill P, Mendelson KL, Slovis TL, Frush D: Safety in pediatric MR and cardiac CT: Results of a membership survey of the Society for Pediatric Radiology—2006. Pediatr Radiol 2007; 37:409–12

30. Kean DM, Worthington BS, Firth JL, Hawkes RC: The effect of magnetic resonance imaging on different types of microsurgical clips. J Neurol Neurosurg Psychiatry 1985; 48:286–7

31. Klucznik R, Carrier D, Pyka R, Haid R: Placement of a ferromagnetic intracerebral aneurysm clip in a magnetic field with a fatal outcome. Radiology 1993; 187:855–6

32. Konings MK, Bartels LW, Smits HFM, Bakker CJG: Heating around intravascular guidewires by resonating RF waves. J Magn Reson Imaging 2000; 12:79–85

33. Laakman RW, Kaufman B, Han JS, Nelson AD, Clampitt M, O'page AM, Haaga JR, Alfidi RJ: MR imaging in patients with metallic implants. Radiology 1985; 157:711–4

34. Moscatel MA, Shellock FG, Morisoli SM: Biopsy needles and devices: Assessment of ferromagnetism and artifacts during exposure to a 1.5 T MR system. J Magn Reson Imaging 1995; 5:369–72

35. Pruefer D, Kalden P, Schreiber W, Dahm M, Buerke M, Thelen M, Oelert H: In vitro investigation of prosthetic heart valves in magnetic resonance imaging: Evaluation of potential hazards. J Heart Valve Dis 2001; 10:410–4

36. Romner B, Olsson M, Ljunggren B, Holtas S, Saveland H, Brandt L, Persson B: Magnetic resonance imaging and aneurysm clips. J Neurosurg 1989; 70:426–31

37. Shellock FG: Prosthetic heart valves and annuloplasty rings: Assessment of magnetic field interactions, heating, and artifacts at 1.5 tesla. J Cardiovasc Magn Reson 2001; 3:317–24

38. Shellock FG: Biomedical implants and devices: Assessment of magnetic field interactions with a 3.0-tesla MR system. J Magn Reson Imaging 2002; 16:721–32

39. Shellock F, Crues J: High field strength MR imaging and metallic biomedical implants: An ex vivo evaluation of deflection forces. AJR Am J Roentgenol 1988; 151:389–92

40. Soulon R, Budinger T, Higgins C: Magnetic resonance imaging of prosthetic heart valves. Radiology 1985; 154:705–7

41. Teitelbaum GP, Lin MC, Watanabe AT, Norfray JF, Young TI, Bradley WG Jr: Ferromagnetism and MR imaging: Safety of carotid vascular clamps. AJNR Am J Neuroradiol 1990; 11:267–72

42. Von Roemeling R, Lanning RM, Eames FA: MR imaging of patients with implanted drug infusion pumps. J Magn Reson Imaging 1991; 1:77–81

43. Wichmann W, Von Ammon K, Fink U, Weik T, Yasargil GM: Aneurysm clips made of titanium: Magnetic characteristics and artifacts in MR. AJNR Am J Neuroradiol 1997; 18:939–44

44. Dempsey MF, Condon B: Thermal injuries associated with MRI. Clin Radiol 2001; 56:457–65

45. Kugel H, Bremer C, Püschel M, Fischbach R, Lenzen H, Tombach B, Van Aken H, Heindel W: Hazardous situation in the MR bore: Induction in ECG leads causes fire. Eur Radiol 2003; 13:690–4

46. Anonymous: ECRI: The safe use of equipment in the magnetic resonance environment. Health Devices 2001; 30:421–44

47. Bashein G, Syrory B: Burns associated with pulse oximetry during magnetic resonance imaging. Anesthesiology 1991; 75:382–3

48. Brown TR, Goldstein B, Little J: Severe burns resulting from magnetic resonance imaging with cardiopulmonary monitoring: Risks and relevant safety precautions. Am J Phys Med Rehabil 1993; 72:166–7

49. Hall SC, Stevenson GW, Suresh S: Burn associated with temperature monitoring during magnetic resonance imaging. Anesthesiology 1992; 76:152

50. Shellock FG, Slimp GL: Severe burn of the finger caused by using a pulse oximeter during MR imaging. AJR Am J Roentgenol 1989; 153:1105

51. Williams EJ, Jones NS, Carpenter TA, Bunch CS, Menon DK: Testing of adult and paediatric ventilators for use in a magnetic resonance imaging unit. Anaesthesia 1999; 54:969–74

52. Anonymous: ECRI hazard report: Patient death illustrates the importance of adhering to safety precautions in magnetic resonance environments. Health Devices 2001; 30:311–4

53. Chaljub G, Kramer LA, Johnson RF III, Singh H, Crow WN: Projectile cylinder accidents resulting from the presence of ferromagnetic nitrous oxide or oxygen tanks in the MR suite. AJR Am J Roentgenol 2001; 177:27–30

54. Colletti PM: Size “H” oxygen cylinder: Accidental MR projectile at 1.5 tesla. J Magn Reson Imaging 2004; 19:141–3

55. Achenbach S, Moshage W, Diem B, Bieberle T, Schibgilla V, Bachmann K: Effects of magnetic resonance imaging on cardiac pacemakers and electrodes. Am Heart J 1997; 134:467–73

56. Anfinsen OG, Berntsen RF, Aass H, Kongsgaard E, Amlie JP: Implantable cardioverter defibrillator dysfunction during and after magnetic resonance imaging. Pacing Clin Electrophysiol 2002; 25:1400–2

57. Avery JE: Loss prevention case of the month: Not my responsibility! J Tenn Med Assoc 1988; 81:523–4

58. Bonnett CA, Elson JJ, Fogoros RN: Accidental deactivation of the automatic implantable cardioverter defibrillator. Am Heart J 1990; 120:696–7

59. Coman JA, Martin ET, Sandler DA, Thomas JR: Implantable cardiac defibrillator interactions with magnetic resonance imaging at 1.5 tesla. J Am Coll Cardiol 2004; 43:138A

60. Erlebacher JA, Cahill PT, Pannizzo F, Knowles JR: Effect of magnetic resonance imaging on DDD pacemakers. Am J Cardiol 1986; 57:437–40

61. Fetter J, Aram G, Holmes DR Jr, Gray JE, Hayes DL: The effects of nuclear magnetic resonance imagers on external and implantable pulse generators. Pacing Clin Electrophysiol 1984; 7:720–7

62. Fiek M, Remp T, Reithmann C, Steinbeck G: Complete loss of ICD programmability after magnetic resonance imaging. Pacing Clin Electrophysiol 2000; 27:1002–4

63. Fontain JM, Mohammed FB, Gottlieb C, Callans DJ, Marchlinski FE: Rapid ventricular pacing in a pacemaker patient undergoing magnetic resonance imaging. Pacing Clin Electrophysiol 1998; 21:1336–9

64. Garcia-Bolao I, Albaladejo V, Benito A, Alegria E, Zubieta JL: Magnetic resonance imaging in a patient with a dual-chamber pacemaker. Acta Cardiol 1998; 53:33–5

65. Gimbel JR, Bailey SM, Tchou PJ, Ruggieri PM, Wilcox EL: Strategies for the safe magnetic resonance imaging of pacemaker-dependent patients. Pacing Clin Electrophysiol 2005; 28:1041–6

66. Gimbel JR, Johnson D, Levine PA, Wilkoff BL: Safe performance of magnetic resonance imaging on five patients with permanent cardiac pacemakers. Pacing Clin Electrophysiol 1996; 19:913–9

67. Gimbel JR, Kanal E, Schwartz KM, Wilkoff BL: Outcome of magnetic resonance imaging (MRI) in selected patients with implantable cardioverter defibrillators (ICDs). Pacing Clin Electrophysiol 2005; 28:270–3

68. Gimbel JR, Trohman RL, Lindsay WC, Clair WK, Wilkoff BL: Strategies for the safe performance of magnetic resonance imaging in selected ICD patients. Pacing Clin Electrophysiol 2002; 25:618

69. Hayes DL, Holmes DR Jr, Gray JE: Effect of 1.5 tesla nuclear magnetic resonance imaging scanner on implanted permanent pacemakers. J Am Coll Cardiol 1987; 10:782–6

70. Heatlie G, Pennell DJ: Cardiovascular magnetic resonance at 0.5T in five patients with permanent pacemakers. J Cardiovasc Magn Reson 2007; 9:15–9

71. Holmes DR Jr, Hayes DL, Gray JE, Merideth J: The effects of magnetic resonance imaging in implantable pulse generators. Pacing Clin Electrophysiol 1986; 9:360–70

72. Lauck G, von Smekal A, Wolke S, Seelos KC, Jung W, Manz M, Luderitz B: Effects of nuclear magnetic resonance imaging on cardiac pacemakers. Pacing Clin Electrophysiol 1995; 18:1549–55

73. Luechinger R, Duru F, Scheidegger MB, Boesiger P, Dandinas R: Force and torque effects of a 1.5 tesla MRI scanner on cardiac pacemakers and ICDs. Pacing Clin Electrophysiol 2001; 24:199–205

74. Luechinger R, Zeijlemaker VA, Pederson EM, Mortensen P, Falk E, Duru F, Candinas R, Boesiger P: In vivo heating of pacemaker leads during magnetic resonance imaging. Eur Heart J 2005; 26:376–83

75. Martin ET, Coman JA, Shellock FG, Pulling CC, Fair R, Jenkins K: Magnetic resonance imaging and cardiac pacemaker safety at 1.5 T. J Am Coll Cardiol 2004; 43:1315–24

76. Pavlicek W, Geisinger M, Castle L, Borkowski GP, Meaney TF, Bream BL, Gallagher JH: The effects of nuclear magnetic resonance on patients with cardiac pacemakers. Radiology 1983; 147:149–53

77. Roguin A, Zviman MM, Meininger GR, Rodrigues ER, Dickfeld TM, Bluemke DA, Lardo A, Berger RD, Calkins H, Halperin HR: Modern pacemaker and implantable cardioverter/defibrillator systems can be magnetic resonance imaging safe: In vitro and in vivo assessment of safety and function at 1.5 T. Circulation 2004; 110:475–82

78. Rozner MA, Burton AW, Kumar AJ: Pacemaker complication during MRI. J Am Coll Cardiol 2005; 45:161–2

79. Schmiedel A, Hackenbroch M, Yang A, Nahle CP, Skowasch D, Meyer C, Schimpf R, Schild H, Sommer T: Magnetic resonance imaging of the brain in patients with cardiac pacemakers: In vitro and in vivo evaluation at 1.5 tesla [in German]. Rofo 2005; 177:731–44

80. Shellock FG, Fieno DS, Thomson LJ, Talavage TM, Berman DS: Cardiac pacemaker: In vitro assessment at 1.5 T. Am Heart J 2006; 2:436–43

81. Shellock FG, Fischer L, Fieno DS: Cardiac pacemakers and implantable cardioverter defibrillators: In vitro magnetic resonance imaging evaluation at 1.5-tesla. J Cardiovasc Magn Reson 2007; 9:21–31

82. Shellock FG, O'Neil M, Ivans V, Kelly D, O'Connor M, Toay L, Crues JV: Cardiac pacemakers and implantable cardioverter defibrillators are unaffected by operation of an extremity MR imaging system. AJR Am J Roentgenol 1999; 172:165–70

83. Sommer T, Vahihaus C, Lauck G, von Smekal A, Reinke M, Hofer U, Block W, Traber F, Schneider C, Gieseke J, Jung W, Schild H: MR imaging and cardiac pacemakers: In vitro evaluation and in vivo studies in 51 patients at 0.5 T. Radiology 2000; 215:869–79

84. Valhaus C, Sommer T, Lewalter T, Schimpf R, Schumacher B, Jung W, Luderitz B: Interference with cardiac pacemakers by magnetic resonance imaging: Are there irreversible changes at 0.5 tesla? Pacing Clin Electrophysiol 2001; 24:489–95

85. Gimbel JR, Lorig RJ, Wilkoff BL: Safe magnetic resonance imaging of pacemaker patients. J Am Coll Cardiol 1995; 25:11A

86. Schueler BA, Parrish TB, Lin JC, Hammer BE, Pangrle BJ, Ritenour ER, Kucharczyk J, Truwit CL: MRI compatibility and visibility assessment of implantable medical devices. J Magn Reson Imaging 1999; 9:596–603

87. Shellock FG, Hatfield M, Simon BJ, Block S, Wamboldt R, Starewica PM, Punchard WFB: Implantable spinal fusion stimulator: Assessment of MRI safety. J Magn Reson Imaging 2000; 12:214–23

88. Bhidayasiri R, Bronstein JM, Sinha S, Krahl SE, Ahn S, Behnke EJ, Cohen MS, Frysinger R, Shellock FG: Bilateral neurostimulation systems used for deep brain stimulation: In vitro study of MRI-related heating at 1.5 T and implications for clinical imaging of the brain. Magn Reson Imaging 2005; 23:549–55

89. Carmichael DW, Pinto S, Limousin-Dowsey P, Thobois S, Allen PJ, Lemieux L, Yousry T, Thornton JS: Functional MRI with active, fully implanted, deep brain stimulation systems: Safety and experimental confounds. Neuroimage 2007; 37:508–17

90. De Andres J, Valía JC, Cerda-Olmedo G, Quiroz C, Villanueva V, Martinez-Sanjuan V, de Leon-Casasola O: Magnetic resonance imaging in patients with spinal neurostimulation systems. Anesthesiology 2007; 106:779–86

91. Finelli DA, Rezai AR, Ruggieri PM, Tkach JA, Nyenhuis JA, Hrdlicka G, Sharan A, Gonzalez-Martinez J, Stypulkowski PH, Shellock FG: MR imaging-related heating of deep brain stimulation electrodes: In vitro study. Am J Neuroradiol 2002; 23:1795–802

92. Heller J, Brackman D, Tucci D, Nyenhuis J, Chou C: Evaluation of MRI compatibility of the modified nucleus multichannel auditory brainstem and cochlear implants. Am J Otol 1996; 17:724–9

93. Rezai AR, Finelli D, Nyenhuis JA, Hrdlicka G, Tkach J, Sharan A, Rugieri P, Stypulkowski PH, Shellock FG: Neurostimulation systems for deep brain stimulation: In vitro evaluation of MRI-related heating at 1.5 tesla. J Magn Reson Imaging 2002; 15:241–50

94. Baker KB, Nyenhuis JA, Hrdlicka G, Rezai AR, Tkach JA, Shellock FG: Neurostimulation systems: Assessment of magnetic field interactions associated with 1.5- and 3-tesla MR systems. J Magn Reson Imaging 2005; 21:72–7

95. Utti RJ, Tsuboi Y, Pooley RA, Putzke JD, Turk MF, Wszolek Z, Witte RJ, Wharen RE Jr: Magnetic resonance imaging and deep brain stimulation. Neurosurgery 2002; 51:1423–31

96. Williams MD, Antonelli PJ, Williams LS, Moorhead JE: Middle ear prosthesis displacement in high-strength magnetic fields. Otol Neurotol 2001; 22:158–61

97. Ferris NJ, Kavnoudias H, Thiel C, Stuckey S: The 2005 Australian MRI safety survey. AJR Am J Roentgenol 2007; 188:1388–94

98. American Society of Anesthesiologists: Standards for basic anesthetic monitoring, Standards, Guidelines and Statements 2006. Available at: http://www.asahq.org/publicationsAndServices/standards/02.pdf. Accessed October 17, 2008

99. Holshouser BA, Hinshaw DB, Shellock FG: Sedation, anesthesia, and physiologic monitoring during MR imaging: Evaluation of procedures and equipment. J Magn Reson Imaging 1993; 3:553–8

100. Odegard KC, Dinardo JA, Tsai-Goddman B, Powell AJ, Geva T, Laussen PC: Anaesthesia considerations for cardiac MRI in infants and children. Paediatr Anaesth 2004; 14:471–6

101. Salvo I, Colombo S, Capocasa T, Torri G: Pulse oximetry in MRI units. J Clin Anesth 1990; 2:65–6

102. Barnett GH, Ropper AH, Johnson KA: Physiological support and monitoring of critically ill patients during magnetic resonance imaging. J Neurosurg 1988; 68:246–50

103. Henneberg S, Hok B, Wiklund L, Sjodin G: Remote auscultatory patient monitoring during magnetic resonance imaging. J Clin Monit 1992; 8:37–43

104. Mason KP, Burrows PE, Dorsey MM, Zurakowski D, Krauss B: Accuracy of capnography with a 30 foot nasal cannula for monitoring respiratory rate and end-tidal CO2 in children. J Clin Monit Comput 2000; 16:259–62

105. Roth JLO, Nugent M, Gray JE, Julsrud RR: Patient monitoring during magnetic resonance imaging. Anesthesiology 1985; 62:80–3

106. Jorgensen NH, Messick JM, Gray J, Nugent M, Berquist TH: ASA monitoring standards and magnetic resonance imaging. Anesth Analg 1994; 79:1141–7

107. Beebe DS, Tran P, Bragg M, Stillman A, Truwitt C, Belani KG: Trained nurses can provide safe and effective sedation for MRI in pediatric patients. Can J Anaesth 2000; 47:205–10

108. Hubbard AM, Markowitz RI, Kimmel B, Kroger M, Bartko MB: Sedation for pediatric patients undergoing CT and MRI. J Comput Assist Tomogr 1992; 16:3–6

109. Manuli MA, Davies L: Rectal methohexital for sedation of children during imaging procedures. AJR Am J Roentgenol 1993; 160:577–80

110. Slovis TL, Parks C, Reneau D, Becker CJ, Hersch J, Carver CD, Ross RD, Tech K, Towbin RB: Pediatric sedation: Short-term effects. Pediatr Radiol 1993; 23:345–8

111. Volle E, Park W, Kaufman HJ: MRI examination and monitoring of pediatric patients under sedation. Pediatr Radiol 1996; 26:280–1

112. Shorrab AA, Demain AD, Atallah MM: Multidrug intravenous anesthesia for children undergoing MRI: A comparison with general anesthesia. Paediatr Anaesth 2007; 17:1187–93

113. Greenberg SB, Faerber EN, Aspinall CL, Adams RC: High-dose chloral hydrate sedation for children undergoing MR imaging: Safety and efficacy in relation to age. AJR Am J Roentgenol 1993; 161:639–41

114. Shepherd JK, Hall-Craggs MA, Finn JP, Bingham RM: Sedation in children scanned with high-field magnetic resonance: The experience at the Hospital for Sick Children, Great Ormond Street. Br J Radiol 1990; 63:794–7

115. Vangerven M, Van Hemelrijck J, Wouters P, Vandermeersch E, Van Aken H: Light anaesthesia with propofol for paediatric MRI. Anaesthesia 1992; 47:706–7

116. Bloomfield EL, Masaryk TJ, Caplin A, Obuchowski NA, Schubert A, Hayden J, Ebrahim ZY, Ruggieri PM, Goske MJ, Ross JS: Intravenous sedation for MR imaging of the brain and spine in children: Pentobarbital versus propofol. Radiology 1993; 186:93–7

117. Bluemke DA, Breiter SN: Sedation procedures in MR imaging: Safety, effectiveness, and nursing effect on examinations. Radiology 2000; 216:645–52

118. Connor L, Burrows PE, Zurakowski D, Bucci K, Gagnon DA, Mason KP: Effects of IV pentobarbital with and without fentanyl on end-tidal carbon dioxide levels during deep sedation. AJR Am J Roentgenol 2003; 181:1691–4

119. De Sanctis Briggs V: Magnetic resonance imaging under sedation in newborns and infants: A study of 640 cases using sevoflurane. Paediatr Anaesth 2005; 15:9–15

120. Malviya S, Voepel-Lewis T, Eldevik OP, Rockwell DT, Wong JH, Tait AR: Sedation and general anaesthesia in children undergoing MRI and CT: Adverse events and outcomes. Br J Anaesth 2000; 84:743–8

121. Mason KP, Sanborn P, Zurakowski D, Karian VE, Connor L, Fontaine PJ, Burrows PE: Superiority of pentobarbital versus chloral hydrate for sedation in infants during imaging. Radiology 2004; 230:537–42

122. Mason KP, Zurakowski D, Connor L, Karian VE, Fontaine PJ, Sanborn PA, Burrows PE: Infant sedation for MR imaging and CT: Oral versus intravenous pentobarbital. Radiology 2004; 233:723–8

123. Merola C, Albarracin C, Lebowitz P, Bienkowski RS, Barst SM: An audit of adverse events in children sedated with chloral hydrate or propofol during imaging studies. Paediatr Anaesth 1995; 5:375–8

124. Pershad J, Wan J, Anghelescu DL: Comparison of propofol with pentobarbital/midazolam/fentanyl sedation for magnetic resonance imaging of the brain in children. Pediatrics 2007; 120:e629–36

125. Sanborn PA, Michna E, Zurakowski D, Burrows PE, Fontaine PJ, Connor L, Mason KP: Adverse cardiovascular and respiratory events during sedation of pediatric patients for imaging examinations. Radiology 2005; 237:288–94

126. Sury MRJ, Harker H, Thyomas ML: Sevoflurane sedation in infants undergoing MRI: A preliminary report. Paediatr Anaesth 2005; 15:16–22

127. Vade A, Sukhani R, Dolenga M, Habisohn-Schuck C: Chloral hydrate sedation of children undergoing CT and MR imaging: Safety as judged by American Academy of Pediatrics guidelines. AJR Am J Roentgenol 1995; 165:905–9

128. Woodthorpe C, Trigg A, Alison G, Sury M: Nurse led sedation for paediatric MRI: Progress and issues. Paediatr Nurs 2007; 19:14–8

129. American Society of Anesthesiologists: Practice advisory for the prevention and management of operating room fires. Anesthesiology 2008; 108:786–801

130. American Society of Anesthesiologists: Standards for postanesthesia care, ASA Standards, Guidelines and Statements. October 2007. Available at: http://www.asahq.org/publicationsAndServices/standards/36.pdf. Accessed October 17, 2008

Back to Top | Article Outline
Appendix 1: Facility Levels for MRI Suites
This Advisory categorizes MRI facilities into three general levels according to the anticipated level of patient care required. These levels describe the physical plant, technical infrastructure, and resources needed to deliver patient care according to standards already established by the ASA and other professional organizations for sedation, anesthesia, and monitored care.
Back to Top | Article Outline
Level I: Facilities That Image Patients Who Do Not Require Medical Support or Physiologic Monitoring
These facilities do not typically have available oxygen supplies, suction, physiologic monitors, resuscitation equipment, or non-MRI medical support personnel on site, although some level 1 facilities may provide such services or equipment. Level 1 facilities do not contain suitable equipment or infrastructure for the care of critical patients, infants, emergency patients, patients needing anesthesia or sedation, or other patients with high-risk medical conditions.
Back to Top | Article Outline
Level II: Facilities That Image Patients Requiring Any Level of Anesthesia or Critical Care, Including Noninvasive or Invasive Monitoring and Life Support
Facilities with this designation provide imaging for patients receiving sedation or anesthesia; intensive care patients requiring continuous monitoring, drug infusions, or mechanical ventilation; and patients needing emergent scans. Non-MRI personnel (e.g., anesthesiologists, emergency physicians, intensivists, house staff, nurses, nurse practitioners) are typically present to provide patient care. Patient monitoring systems designated as safe/conditional for zone IV are required in these facilities. Level II facilities provide medical gases (oxygen, nitrous oxide, air), patient suction, and evacuation of anesthetic gases. Back up oxygen resources in nonferromagnetic (e.g., aluminum) canisters are also available. Finally, oxygen and suction are readily available in zone II or III for patients who need to be evacuated from zone IV for emergent resuscitation.
Back to Top | Article Outline
Level III: Facilities That Provide Imaging for Operative Procedures
Facilities with this designation contain all resources (i.e., physical plant and technical infrastructure) commensurate with level II facilities and, in addition, provide an operative team of non-MRI personnel with the appropriate surgical tools and equipment (e.g., availability of additional gases such as nitrogen to power surgical equipment). All legal codes and standards for operating rooms (such as air turnover and ventilation) apply. Cited Here...
Back to Top | Article Outline
Appendix 2: Primary Findings of the Advisory Task Force
I. Education
* All anesthesiologists should have general safety education on the unique physical environment of the MRI scanner, and specific education regarding the specific features of individual scanners within their institution.
○Education should emphasize safety for entering zones III and IV, with special emphasis on hazards in this environment and effects on monitoring capabilities.
○Education should address potential health hazards (e.g., high decibel levels and high-intensity magnetic fields).
○Education should address necessary precautions to deal with the specific field strength and the safety of the MRI scanners within their institutions.
○Education should include information regarding ferromagnetic items (e.g., stethoscopes, pens, wallets, watches, hair clips, name tags, pagers, cell phones, credit cards, batteries) and implantable devices (e.g., spinal cord stimulators, implanted objects) that should not be brought into zone III or IV of the MRI suite or should be brought in with caution.
* Anesthesiologists should work in collaboration with radiologists, technologists, and physicists within their institutions to ensure that the above topics are included in their safety training programs.
* Education should include how to safely respond to code blue situations in zones III and IV, and this information should be integrated into protocols for the designated code blue team.
Back to Top | Article Outline
II. Screening of Anesthesia Care Providers and Ancillary Support Personnel
* The anesthesiologist should work in collaboration with the MRI medical director or designee (e.g., safety officer) to ensure that all anesthesia team personnel entering zone III or IV have been screened for the presence of ferromagnetic materials, foreign bodies, and implanted devices.
Back to Top | Article Outline
III. Patient Screening
* For every case, the anesthesiologist should communicate with the patient, referring physician, and radiologist to determine whether the patient:
○Presents with a high-risk medical condition (e.g., neonatal status or prematurity, intensive or critical care status, impaired respiratory function; hemodynamic instability and vasoactive infusion requirements; comorbidities such as obesity and peripheral vascular disease)
○Requires equipment (e.g., physiologic or invasive monitors; intubation, oxygenation, or ventilation equipment)
○Has been screened for implanted devices (e.g., pacemakers, cardioverter–defibrillators, nerve stimulators)
○Has been screened for implanted ferromagnetic items (e.g., surgical clips, prosthetic heart valves)
○Has been screened for the presence of imbedded foreign bodies (e.g., orbital iron filings, eyeliner tattoos)
* The anesthesiologist should communicate with the technologist to ensure that the patient has been screened for the presence of foreign bodies on the patient (e.g., pierced jewelry, rings) before entering zone III.
* If a patient presents with a high-risk medical condition, the anesthesiologist should collaborate with all participants, including the referring physician, radiologist, and technologist, to determine how the patient will be managed during the MRI procedure.
○Anticipated changes in level of sedation, muscle relaxation, or ventilation may also place a patient in a high-risk situation.
* For patients with acute or severe renal insufficiency, the anesthesiologist should not administer gadolinium because of the increased risk of nephrogenic systemic fibrosis.
* Anesthesiologists should work with their institutions to properly identify and label anesthesia-related equipment according to convention (safe, unsafe, or conditional) for each MRI scanner.
* For each MRI location, anesthesiologists should determine the safety and effectiveness of the equipment needed by the patient during the procedure.
○Care should be taken to ensure that the patient's equipment does not interfere with image acquisition or quality.
* Cardiac pacemakers and implantable cardioverter–defibrillators are generally contraindicated for MRI.
○When MRI is considered essential by the referring physician and consulting radiologist, a plan for managing these patients during the scan should be developed in collaboration with the ordering physician, medical director or on-site radiologist, and other appropriate consultants (e.g., patient's pacemaker specialist or cardiologist, diagnostic radiologist, device manufacturer).
* MRI may be performed on a limited basis for patients with certain implanted electronic devices (e.g., deep brain stimulators, vagal nerve stimulators, phrenic nerve stimulators, wire-containing thermodilution catheters, cochlear implants).
○In consultation with the referring physician, the radiologist responsible for the procedure, and the neurosurgeon, the anesthesiologist should ensure that the presence of the device has been noted and determined to be MRI safe/conditional before imaging of these patients.
Back to Top | Article Outline
IV. Preparation
* For every case, the anesthesiologist should prepare, with support personnel, a plan for providing optimal anesthetic care within the special environment of the MRI suite.
○In addition to addressing the medical needs of the patient, features of the plan should include (1) requirements of the scan and personnel needs, (2) positioning of equipment, (3) special requirements or unique issues of patient or imaging study, (4) positioning of the anesthesiologist and the patient, and (5) planning for emergencies.
* The anesthesiologist should communicate with the radiology personnel to determine the requirements for the scan (e.g., duration of the scan, position of the patient or area of the body in the scanner, positioning of receiver coils, need for periods of paused respiration).
* The anesthesiologist should communicate with other anesthesia team members regarding individual roles for anesthetic care.
* The anesthesiologist should collaborate with the MR technologist and/or facility biomedical engineer to determine and demarcate the optimal and safe location of movable equipment in relation to the gauss lines within the MRI suite.
* The anesthesiologist should choose a location or position for optimal patient observation and vigilance during delivery of care, whether in zone III or IV.
○Anesthesiologists should have (1) a clear line of sight of the patient and physiologic monitors, whether by direct observation or by video camera; (2) anesthetic delivery equipment located for optimal control of anesthetic depth and rapid intervention; and (3) access to hospital information systems integral to patient care.
○In preparing for positioning, the anesthesiologist should take into account potential electromagnetic and auditory hazards.
* Anesthesiologists should prepare a plan for rapidly summoning additional personnel in the event of an emergency.
○The anesthesiologist should ensure that (1) emergency equipment and drugs are immediately accessible; (2) emergency communication (e.g., phone or code button) is immediately available; and (3) an evacuation plan is in place, including an appropriate location outside the scan room (zone IV) for resuscitation.
-This location should be complete with physiologic monitors, oxygen, suction, and other appropriate resuscitation equipment.
Back to Top | Article Outline
V. Patient Management during MRI
* Monitoring
○MRI patients should be monitored in a manner consistent with the ASA Standards for Basic Anesthetic Monitoring.
○The anesthesiologist should be familiar with the expected limitations of available monitoring equipment.
-Information from electrocardiograms may be limited due to superimposed voltages from blood flow in the high magnetic field (e.g., ST-segment interpretation may be unreliable, even with highly filtered monitors).
○The anesthesiologist should make sure that all monitors used in zone IV are safe/conditional for the scan.
○A monitor should be available to view vital signs from zone III when the anesthesia care provider is not in zone IV.
○Additional care should be taken in positioning electrocardiogram and other monitor leads to eliminate burns, even with nonferromagnetic leads.
* Anesthetic care
○Although lighter levels of anesthesia may be appropriate during an MRI scan, the anesthesiologist should be aware that these lighter levels may result in airway complications (e.g., laryngospasm, coughing, or other airway compromise), which may necessitate interruption of the scan for urgent treatment and alteration of anesthetic depth.
-Institutional circumstances, patient characteristics, and anesthesiologist preference may warrant more aggressive airway management and deeper anesthetic levels.
○Anesthesiologists should ensure that patients who receive moderate or deep sedation are monitored in a manner consistent with their institution's protocol for monitoring similarly sedated patients elsewhere in the facility.
○Monitoring of exhaled carbon dioxide should be considered for all patients receiving deep sedation and for patients whose ventilation cannot be directly observed during moderate sedation.
○Monitoring oxygenation by pulse oximetry is not a substitute for monitoring ventilatory function.
○Equipment and drugs for anesthetic care in the MRI suite should mirror what is available in other anesthetizing locations, including (1) an integrated anesthesia machine, medical gases, and waste anesthesia gas disposal or gas scavenging, when inhalational anesthesia is administered; (2) suction; (3) adequate electrical outlets and lighting; and (4) storage areas for equipment and drugs.
○Equipment used in the MRI suite should be appropriate for the age and size of the patient.
○MRI-safe/conditional anesthesia machines are always preferred for use in an MRI facility.
-When an MRI-safe/conditional anesthesia machine is not available, inhalational anesthetics can be administered from an anesthesia machine inside zone III via an elongated circuit through a wave guide.
-If total intravenous anesthesia is used, it should be administered by using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e., MRI unsafe) pumps in zone III with intravenous tubing passed through a wave guide, or (3) periodic bolus injections in zone III or IV.
* Although an anesthesia machine may not be required for the administration of total intravenous anesthesia, there must be equipment immediately available for the administration of positive pressure ventilation with oxygen.
* Airway management
○The anesthesiologist should have an advance plan in place to deal with instrumentation of the airway and common airway problems (e.g., obstruction, secretions, laryngospasm, apnea and hypoventilation) when patients are in an MRI environment.
○If the patient is at risk for airway compromise, more aggressive airway management (e.g., use of a endotracheal tube or laryngeal mask airway), should be instituted because the patient's airway may be less accessible when the patient is in the scanner.
○Complex airway management (e.g., fiberoptic intubation) should be performed in a controlled environment outside of zone IV.
○Alternative airway devices should be immediately available in the MRI suite.
○Suction equipment should be immediately accessible to the patient's airway at all times.
Back to Top | Article Outline
VI. Management of Emergencies
* When a patient has a medical emergency (e.g., cardiopulmonary arrest) in the MRI scanner, the following should occur: (1) Immediately remove the patient from zone IV while initiating cardiopulmonary resuscitation, if indicated; (2) call for help; and (3) transport the patient to a previously designated safe area for resuscitation that is not in zone IV.
○This location should be as close to zone IV as possible so as not to delay resuscitation efforts, and should contain the following resuscitation equipment: a defibrillator, vital signs monitors, and a code cart that includes resuscitation drugs, airway equipment, oxygen, and suction.
* When a fire occurs in the MRI suite, team members should perform their preassigned fire management task as quickly as possible, in accordance with the ASA Practice Advisory for the Prevention and Management of Operating Room Fires.
○If a team member cannot rapidly perform his or her task in the predetermined order, other team members should perform their tasks without waiting.
○When a team member has completed a preassigned task, he or she should help other members perform tasks that are not yet complete.
* In the case of projectile emergencies, team members should perform their institution's protocol in reaction to this occurrence.
○If possible, immediately remove the patient from zone IV and discontinue the scan.
○If the patient is injured, proceed with medical emergency management as indicated above.
○A controlled quench may be necessary to remove the patient from the bore.
* When a quench occurs, team members should perform their institution's protocol in reaction to this occurrence. If possible, (1) immediately remove the patient from zone IV and (2) immediately administer oxygen to the patient.
○Powerful static magnetic fields may persist after a quench, and therefore the usual precautions apply when entering zone IV.
* Emergency response personnel should be restricted from entering zone IV during any environmental emergency because of the persistent magnetic field.
Back to Top | Article Outline
VII. Postprocedure Care
* The anesthesiologist should collaborate with the radiologist and other staff in the postprocedure care of the patient.
* Patients receiving sedation or anesthesia within the MRI suite should have access to postanesthetic care consistent with that provided in other areas of the institution, including transport to other recovery rooms, dedicated intensive care, or recovery areas within the MRI suite.
* In all situations, intensive care and recovery areas should include access to vital sign monitors, oxygen, suction, resuscitation equipment, and trained personnel.
* Patients should be given oral and written discharge instructions.
Cited Here...
Back to Top | Article Outline
Appendix 3: Methods and Analyses
For this Advisory, a systematic review and evaluation of the literature was conducted, and formal survey opinion data were obtained from experts and ASA members. Informal opinion-based information from other sources (e.g., open forums, Internet postings) was also used in the development of this document. Both the literature evaluation and the survey opinion data were based on evidence linkages, or statements regarding potential relations between patient care interventions and safety outcomes in the MRI suite.*** The evidence linkage interventions are listed below.
I. Education
1. MRI education for magnet hazards
2. MRI education for monitoring limitations
3. MRI education for long-term health hazards
II. Screening of Anesthesia Care Providers and Ancillary Support Personnel
4. Mandatory screening of all personnel entering zone III or IV
III. Patient Screening
5. Patient-related risks for adverse outcomes related to MRI
6. Equipment-related risks for adverse outcomes related to MRI
IV. Preparation
7. Planning for the anesthetic care of the patient for the scan
8. Planning for rapidly summoning additional personnel in the event of an emergency
V. Patient Management during MRI
9. Monitoring during MRI
10. Anesthetic care during MRI
11. Airway management during MRI
VI. Management of Emergencies
12. Medical emergencies
13. Environmental emergencies
VII. Postprocedure Care
14. Postprocedure care consistent with that provided for other areas of the institution
Back to Top | Article Outline
A. State of the Literature
For the literature review, potentially relevant studies were identified via electronic and manual searches of the literature. The literature search covered a 36-yr period from 1973 through 2008. More than 1,200 citations were initially identified, yielding a total of 343 articles that addressed topics related to the evidence linkages and met our criteria for inclusion. After review of the articles, 186 studies did not provide direct evidence and were subsequently eliminated. A total of 157 articles contained direct linkage-related evidence (see Supplemental Digital Content 1, which is a complete list of references used to develop this Advisory, http://links.lww.com/A623).††† No evidence linkage contained enough studies with well-defined experimental designs and statistical information to conduct a quantitative analysis (i.e., meta-analysis).
Interobserver agreement among Task Force members and two methodologists was established by interrater reliability testing. Agreement levels using a κ statistic for two-rater agreement pairs were as follows: (1) type of study design, κ = 0.49–0.85; (2) type of analysis, κ = 0.54–0.93; (3) evidence linkage assignment, κ = 0.77–1.00; and (4) literature inclusion for database, κ = 0.78–1.00. Three-rater chance-corrected agreement values were (1) study design, Sav = 0.65, Var (Sav) = 0.009; (2) type of analysis, Sav = 0.69, Var (Sav) = 0.010; (3) linkage assignment, Sav = 0.85, Var (Sav) = 0.004; and (4) literature database inclusion, Sav = 0.85, Var (Sav) = 0.013. These values represent moderate to high levels of agreement.
Back to Top | Article Outline
B. Consensus-based Evidence
Consensus was obtained from multiple sources, including (1) survey opinion from consultants who were selected based on their knowledge or expertise in MRI, (2) survey opinions solicited from active members of the ASA, (3) testimony from attendees of a publicly held open forum at two national anesthesia meetings, (4) Internet commentary, and (5) Task Force opinion and interpretation. The survey rate of return was 63% (n = 50 of 79) for the consultants, and 989 surveys were received from active ASA members. Results of the surveys are reported in tables 2 and 3 and are reported in summary form in the text of the Advisory.
The consultants were asked to indicate which, if any, of the evidence linkages would change their clinical practices if the Advisory was instituted. The rate of return was 29% (n = 23 of 79). The percent of responding consultants expecting a change in their practice associated with each linkage topic was as follows: (1) education, 30%; (2) screening of anesthesia care providers and ancillary support personnel, 13%; (3) patient screening, 26%; (4) preparation,13%; (5) patient management during MRI—monitoring, 4%; (6) patient management during MRI—anesthetic care, 0%; (7) patient management during MRI—airway, 0%; (8) patient management during MRI—emergencies, 13%; and (9) postprocedure care, 9%. Seventy-four percent indicated that their clinical practice would not need new equipment, supplies, or training to implement the Practice Advisory. Eighty-five percent indicated that the Advisory would not require ongoing changes in their practice that would affect costs. Ninety-five percent of the respondents indicated that the Advisory would have no effect on the amount of time spent on a typical case, and 5% indicated that there would be a 10-min increase in the amount spent on a typical case with the implementation of this Advisory. Cited Here...
† 82nd Clinical and Scientific Congress of the International Anesthesia Research Society, San Francisco, California, March 30, 2008, and Annual Meeting of the Society for Pediatric Anesthesia, San Diego, California, April 5, 2008. Cited Here...
‡ All meta-analyses are conducted by the ASA methodology group. Meta-analyses from other sources are reviewed but not included as evidence in this document. Cited Here...
§ When an equal number of categorically distinct responses is obtained, the median value is determined by calculating the arithmetic mean of the two middle values. Ties are calculated by a predetermined formula. Cited Here...
∥ See US Food and Drug Administration alert. Available at: http://www.fda.gov/CDER/Drug/InfoSheets/HCP/gcca_200705.htm. Accessed October 17, 2008. Cited Here...
# Equipment is categorized as safe, unsafe, or conditional for use in the MRI environment. MRI safe equipment is identified by the American Society for Testing and Materials as having no ferromagnetic parts or radiofrequency interference. MRI unsafe equipment is identified as having ferromagnetic parts or being affected by radiofrequency interference. MRI conditional equipment may be safe in certain locations of the suite depending on gauss line locations, but cannot be identified as having no ferromagnetic parts (see American Society for Testing and Materials Practice Standards F2503, F2119, and F2052, www.astm.org). In the past, equipment was described as MRI compatible, but because the safety of this equipment depended on the particular MRI environment, the word conditional now applies. Cited Here...
** American Society of Anesthesiologists: Practice advisory for the perioperative management of patients with cardiac rhythm management devices: Pacemakers and implantable cardioverter–defibrillators. Anesthesiology 2005; 103:186–98. Cited Here...
†† American Society of Anesthesiologists: Practice guidelines for sedation and analgesia by non-anesthesiologists: An updated report. Anesthesiology 2002; 96:1004–17. Cited Here...
‡‡ When remodeling or building a new facility, input from the anesthesiologist is critical. Cited Here...
§§ An MRI facility that is newly built or that undergoes a major renovation should have an MRI-safe/conditional anesthesia machine. Cited Here...
∥∥ A wave guide is a copper-lined conduit with a specific length and diameter that maintains radiofrequency isolation of the magnet room installed during construction of the MRI suite. Wires or conducting material act as an antenna and should not be passed through a wave guide. Cited Here...
## When remodeling or building a new facility, an attempt should be made to locate recovery and resuscitation in proximity to the MRI suite. Cited Here...
*** Outcomes for the listed interventions refer to the occurrence of safety-based outcomes. Cited Here...
††† A complete list of references used to develop this Advisory is also available by writing to the American Society of Anesthesiologists. Cited Here...

Cited By:

This article has been cited 1 time(s).

Anasthesiologie & Intensivmedizin
Sedation for diagnostic and therapeutic measures in children
Philippi-Hohne, C; Becke, K; Wulff, B; Schmitz, B; Strauss, J; Reinhold, P
Anasthesiologie & Intensivmedizin, 51(): S603-S614.

Back to Top | Article Outline

Supplemental Digital Content

Back to Top | Article Outline

© 2009 American Society of Anesthesiologists, Inc.

Publication of an advertisement in Anesthesiology Online does not constitute endorsement by the American Society of Anesthesiologists, Inc. or Lippincott Williams & Wilkins, Inc. of the product or service being advertised.
Login

Article Tools

Images

Share