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Economics, Education, and Policy: Research Reports

Characteristics of Emergency Pages Using a Computer-Based Anesthesiology Paging System in Children and Adults Undergoing Procedures at a Tertiary Care Medical Center

Weingarten, Toby N. MD*; Abenstein, John P. MD, MSEE; Dutton, Claire H. SRNA; Kohn, Melinda A. SRNA; Lee, Elizabeth A. SRNA; Mullenbach, Tami E. SRNA; Narr, Bradly J. MD*; Schroeder, Darrell R. MS§; Sprung, Juraj MD, PhD*

Author Information
doi: 10.1213/ANE.0b013e31826bb636
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Sudden life-threatening event during anesthesia requires a prompt response, and in certain situations, multiple providers need to help manage an acutely deteriorating patient. In clinical practices, common communication modalities include alphanumeric paging or overhead paging.1,2 Although such modes are available at Mayo Clinic, our practice universally uses a proprietary computer-based anesthesiology paging system (CAPS) previously described.3 Activation of CAPS quickly provides a visual alert throughout the operating suites that the attending anesthesiologist is needed or, in the event of an emergency, provides visual and audible alerts that all available personnel should report immediately to the specified location. Intraoperative emergency pages should be viewed as the equivalent of “emergency response team” activations.4

Previous reports of intraoperative complications have noted that adverse events were more frequent in infants and children.5,6 These early studies found that up to 82% of the intraoperative incidents in children were due to preventable errors.7 Keenan et al.8,9 suggested that when pediatric trained anesthesiologists care for children, the rate of serious adverse events may be reduced. At Mayo Clinic, fellowship trained anesthesiologists care for all of our complex pediatric patients including all children younger than 2 years. The aim of our descriptive study is to report the frequency, indications, and major outcomes of intraoperative emergency pages among children and adults undergoing procedures in a contemporary anesthesia practice. We hypothesized that the frequency of emergency pages would still be higher in infants (children younger than 1 year of age) compared with older children and adults despite the engagement of pediatric anesthesiologists in their care.


The approval for review of medical records without the need for written consent was obtained from the Mayo Clinic IRB.

Paging System and Patient Identification

Activation of CAPS is managed through commands on keypad controllers mounted at all anesthesia care locations (Fig. 1A), and information is displayed on interconnecting LED screens conspicuously mounted throughout the procedural environment (Fig. 1B). Specifics of this activation have been described3 and are briefly summarized in the legend of Figure 1. Response to the emergency page is prompt, and in addition to the attending anesthesiologist, all other available staff and auxiliary personnel respond because it is extremely difficult to narrow the scope of the alert. Since January 1, 2005, all pages made with the CAPS are stored in a Microsoft SQL Server (Microsoft Corp., Redmond, WA) database. We identified all patients whose intraoperative course resulted in an emergency page from January 1, 2005 to July 31, 2010, at the 2 hospitals associated with Mayo Clinic in Rochester, Minnesota (Saint Marys and Methodist). Emergency pages that occurred in postanesthesia recovery units or diagnostic suites were excluded from analyses because patient identity could not be accurately determined.

Figure 1
Figure 1:
Components of the computer-based anesthesiology paging system (CAPS). Activation of CAPS is managed through commands on keypad controllers (A), which are mounted at all anesthesia care locations. Keypad controllers interface with LED display screens (B) conspicuously mounted throughout the procedural environment. The keypad is activated by a push of a single button to visually display which personnel (e.g., attending anesthesiologist PHYSICIAN, certified registered nurse anesthetist CRNA, anesthesia technician AN TECH, pathologist PATH, autotransfusion personnel AUTOTX, monitoring technician MON TECH, or laboratory personnel LAB) are needed at specific location. Besides emergency page (bright red flashing display accompanied with an audible alarm as shown on the picture), CAPS can send nonurgent visual page (green light) and urgent page (orange light). B, Emergent page in red flashing lights. The abbreviation “C209 A” indicates that the anesthesiologist and other available personnel are needed emergently in operating room 209, which is located in the C section of the operating suite.

Data Abstraction

All data were abstracted from the electronic medical records and entered manually into the web-based Research Electronic Data Capture (REDCap®) system (Version 3.6.7; Vanderbilt University, Nashville, TN).10 Data abstracted included demographics, ASA physical status, specific comorbidities, intraoperative and postoperative events, and major outcomes. Comorbid conditions were defined according to criteria previously used for outcome studies at Mayo Clinic11 and include cardiovascular, peripheral vascular, and respiratory diseases; diabetes mellitus; and neurologic conditions (e.g., stroke, developmental delay). The anesthetic record was reviewed for type of anesthesia (combination regional and general anesthetics were considered general anesthetics) and type of in-room anesthesia provider (certified registered nurse anesthetist, student registered nurse anesthetist SRNA, or anesthesia resident physician). At our institution, in-room providers administer anesthesia under the direction of an attending anesthesiologist who is present during induction, emergence, and critical portions of the anesthetic. The supervision ratio ranges from 1:2 as a first set of cases in the morning, to 1:3 or 1:4 later in the day.

Indications for the emergency page were identified from notations in the medical records, or by changes in vital signs, and medications, interventions, or blood products administered. The probable primary cause was determined by consensus of the 2 senior authors (TNW, JS) attributed to 1 of 4 main categories: (1) hemodynamic, which includes 3 subcategories: (a) hypotension (decrease of systolic blood pressure not explained by a dysrhythmia), (b) dysrhythmias (including those associated with cardiac arrest not related to hypoxemia or hypotension), and (c) hypertension; (2) airway-related events (e.g., inability to intubate, mask ventilate, accidental extubation), or respiratory-related events (e.g., hypoxemia, bronchospasm, aspiration, or laryngospasm); (3) miscellaneous causes (e.g., seizures, anaphylaxis, or inadequate anesthesia); and (4) unknown etiology. Inadequate anesthesia was defined from notation in the anesthetic record or the administration of additional inhaled or IV anesthetics. Timing of pages was recorded as induction (within 10 minutes of tracheal intubation), maintenance, or emergence (after surgical closure and within 10 minutes after tracheal extubation). Response time to emergency page was quantified by calculating the difference in time from its activation to the time it was turned off.

Interventions in response to the emergency pages were recorded and classified as respiratory, major cardiovascular (cardiopulmonary resuscitation, cardioversion, unplanned cardiopulmonary bypass), administration of potent cardiovascular medications, changes in anesthetic or surgical management, transfusion of blood products, and miscellaneous interventions. Cardiac arrest was considered only if the chest compressions and/or cardioversion for a nonperfusing dysrhythmia were performed. Intraoperative and 30-day mortality rates were recorded.

Statistical Analyses

The frequency of emergency pages (per 1000 anesthetics) was calculated overall and also according to age categories based on subjectively determined, but clinically relevant, cut points (age younger than 1 year [infants], 1–2, 3–10, 11–17, 18–29, 30–49, 50–64, 65–74 years, and older than 74 years). This information is presented using point estimates and exact binomial 95% confidence intervals (CIs). Unless otherwise specified, data are summarized using mean ± SD or median (25th, 75th, 95th percentiles) for continuous variables and proportions for categorical variables. Patient and procedure characteristics, treatments, and outcomes were compared between adults and children using the Wilcoxon rank sum test for continuous variables and Fisher exact test for categorical variables. Two-tailed P values ≤0.05 were considered statistically significant. Analyses were performed using SAS statistical software (Version 9.2; SAS Institute, Inc., Cary, NC).


During the study time frame, 258,135 procedures were performed under the care of anesthesia teams in our main operating suites, and of those, 32,103 (12.4%) were children (younger than 18 years). A total of 370 emergency pages were recorded at an overall rate of 1.4 per 1000 cases (95% CI, 1.3–1.6). Of these emergency pages, 309 were for adults (1.4 per 1000; 95% CI, 1.2–1.5) and 61 for children (1.9 per 1000; 95% CI, 1.5–2.4). Figure 2 shows the frequency of emergency pages according to age. Infants had the highest rate (9.4 per 1000; 95% CI, 5.7–14.4; P < 0.001 compared with each other age category).

Figure 2
Figure 2:
Frequency of emergency pages in the main operating rooms according to age of patients. Values plotted are the point estimate with bars extending to the upper and lower bounds of the 95% confidence interval (CI). The overall emergency page activation rate was 1.4 per 1000 cases (95% CI, 1.3–1.6). Pairwise comparisons between age groups were performed using the χ2 test. To account for multiple comparisons (36 pairwise comparisons), P ≤ 0.001 was used to denote statistical significance. From these pairwise comparisons, infants were found to have a significantly higher rate of emergency paging compared with each other age group (all P < 0.001).

Demographics, comorbidities, surgical characteristics, and characteristics of the emergency paging activation are summarized separately for adults and children in Tables 1 and 2. Figure 3 shows the main etiological categories for emergency page activation. The causes differed between adults and children. In adults, the most frequent causes were hemodynamic (55.0%), followed by airway or respiratory-related events (33.0%), whereas in children, airway or respiratory-related events occurred most often (60.7%). The specific circumstances surrounding airway-related events are listed in Table 3. Interventions in response to emergency pages are shown in Table 4. Cardiac arrests before or during emergency page and overall mortality are summarized in Table 5.

Table 1
Table 1:
Demographic and Surgical Characteristics in Patients Who Had an Emergency Page
Table 2
Table 2:
Anesthetic Characteristics and Causes for Emergent Page Events
Table 3
Table 3:
Emergency Page Associated with Airway-Related Emergencies
Table 4
Table 4:
Interventions Performed During Emergency Page
Table 5
Table 5:
Cardiac Arrest and Mortality in Adult and Pediatric Patients Who Had an Emergent Page
Figure 3
Figure 3:
Main causes for emergency pages.


We confirmed that intraoperative emergency pages, mostly due to respiratory causes, are more common in infants than in children 1 to 2 years old, despite both groups being cared for by pediatric trained anesthesiologists. This may be attributed to higher propensity for sudden development of bronchospasm, laryngospasm, and/or oxyhemoglobin desaturation in infants.12,13 Furthermore, more than any other emergency, a sudden respiratory event may occur regardless of coexisting comorbidities, which is suggested by our finding that 88.3% of all our infants with respiratory emergencies were ASA physical status ≤II. In the second year of life, and later through childhood and adulthood, the rate of intraoperative emergency pages remained consistently low (Fig. 2). The majority of emergency pages in adults were associated with cardiovascular causes, which typically develop more gradually; therefore, the anesthesiologist could be paged nonemergently, and this may explain why the rate of emergency pages did not increase in the elderly.

Approximately 85% of in-room providers at the Mayo Clinic are certified registered nurse anesthetists and they activated 51% of the emergency pages, whereas trainees, resident physicians and SRNAs cover 6% and 9% of cases, respectively, and accounted for 49% of emergency pages. Hence, it seems that trainees had a disproportionately higher rate of emergency page activations. This may suggest that trainees activate an emergency page for lower acuity problems or may have a lower threshold for requesting emergency assistance. Unfortunately, because our analysis dataset does not have detailed information (e.g., provider training level) for all procedures performed during this study period, we could not assess whether level of training is a risk for emergency page activation.

It has been shown that there is an association between supervision ratio and the number of lapses during the first-case starts.14 However, in our practice, first round cases are assigned to attending anesthesiologists at a 1:2 ratio, and the first-case starts are staggered. In addition, emergency pages in our practice were uniformly distributed throughout the morning until early afternoon, a time during which our operating rooms are at full working capacity (10%–14% of all pages occurred at each hour between 08:00 and 14:00) and attending anesthesiologist coverage generally increases to 1:3 or 1:4 as the day progresses. This suggests that the emergency pages are associated more with the number of cases performed rather than the attending anesthesiologist supervision ratio.

Furthermore, most pages occurred during anesthesia maintenance when the attending anesthesiologist is least likely to be present in the room. Alternatively, when the attending anesthesiologist is present, at induction or emergence, it may be less likely for the page to be activated. Finally, faster responses to emergency pages for adults during standard versus nonstandard working hours may reflect the fact that more attending anesthesiologists are available to respond during standard working hours. The similar response times to pediatric emergency pages between standard work times and nonstandard times may reflect that off-hour pediatric emergency cases, in contrast to adults, are typically covered in 1:1 ratio, with the pediatric anesthesiologist present nearby.

Limitations of the Study

Our report does not precisely provide the rates of intraoperative complications, because emergency page activation cannot uniformly be equated to complication. For example, emergency pages can be triggered erroneously, for nonemergent situations, or reasons unrelated to patient care (e.g., 1 emergency page activation recently occurred because of a syncopal episode in a pregnant nurse). These non–patient-related activations may account for some of the emergency pages with no supporting documentation in the medical records. At the same time, the rate of emergency pages likely represents an underestimate of intraoperative adverse events because the attending anesthesiologist may have been present during the event or paged in a less urgent manner (green or orange light). However, in serious situations (i.e., cardiac arrest), even if present in the room, anesthesiologists may activate the emergency page to summon additional resources; therefore, our report of intraoperative cardiac arrests provides a reasonable estimate. Furthermore, for our study, we obtained overall denominators only according to age and for this reason, we cannot estimate or compare the frequency of emergency pages under various conditions (e.g., by day of week, by time of day, or according to staff supervision ratio, or incidence in regard to the type of in-room provider at the time of emergency page). Because our practice has a long tradition that only pediatric fellowship trained anesthesiologists care for more complex cases and the youngest children, we cannot assess the role of specialty trained anesthesiologists on the rate of emergency pages. Finally, CAPS is a proprietary paging system; therefore, our experience may not be generalizable to other settings with different communication systems.

In conclusion, the frequency of emergency pages remains highest in infants despite being cared for by pediatric anesthesiologists. The rate of emergency pages remains at low levels after the first year of life and throughout adulthood. Intraoperative events resulting in an emergency page in infants were more likely related to respiratory complications and less due to comorbid conditions.


Name: Toby N. Weingarten, MD.

Contribution: This author helped design the study, analyze the data, and write the manuscript.

Attestation: Toby N. Weingarten has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.

Name: John P. Abenstein, MD, MSEE.

Contribution: This author helped design the study and write the manuscript.

Attestation: John P. Abenstein has seen the original study data and approved the final manuscript.

Name: Claire H. Dutton, SRNA.

Contribution: This author helped analyze the data.

Attestation: Claire H. Dutton has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Melinda A. Kohn, SRNA.

Contribution: This author helped analyze the data.

Attestation: Melinda A. Kohn has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Elizabeth A. Lee, SRNA.

Contribution: This author helped analyze the data.

Attestation: Elizabeth A. Lee has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Tami E. Mullenbach, SRNA.

Contribution: This author helped analyze the data.

Attestation: Tami E. Mullenbach has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Bradly J. Narr, MD.

Contribution: This author helped design the study and write the manuscript.

Attestation: Bradly J. Narr has seen the original study data and approved the final manuscript.

Name: Darrell R. Schroeder, MS.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Darrell R. Schroeder has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Name: Juraj Sprung, MD, PhD.

Contribution: This author helped design the study, analyze the data, and write the manuscript.

Attestation: Juraj Sprung has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

This manuscript was handled by: Franklin Dexter, MD, PhD.


We thank Emily Pavey, Data Analyst, and Theresa Hanson for secretarial help.


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