Perioperative nursing is defined as “nursing care provided to patients before, during, and after surgery and invasive procedures” by the Association of periOperative Registered Nurses (AORN). The practice of perioperative nursing occurs in the OR, ambulatory surgery centers, interventional radiology suites, endoscopy suites, and physician's offices. Formerly, perioperative nursing was thought of as occurring strictly in the surgical suite. Today, the broader definition of perioperative nursing describes preoperative preparation of the patient and family, intraoperative care, and postanesthesia care, including discharge instructions. The AORN has developed a Perioperative Nursing Data Set to provide a framework for nursing practice in perioperative care.
Two conditions that may have serious consequences during the perioperative period are obstructive sleep apnea (OSA) and malignant hyperthermia (MH). Guiding patients safely through surgery includes a basic knowledge of these conditions and their management.
To sleep, perchance to dream
OSA is defined as a syndrome in which an individual has periods of apnea (cessation of airflow) lasting longer than 10 seconds during sleep. These episodes of apnea occur five or more times per hour of sleep, with decreased oxygen saturation. The muscles at the back of the throat collapse and the airway is obstructed, resulting in the person awakening during the sleep cycle.
Patients with OSA have associated morbidity that increases in the perioperative period. There's an increased risk of coronary artery disease, congestive heart failure, hypertension, myocardial infarction, stroke, and gastroesophageal reflux disease. Undiagnosed OSA poses a variety of problems for anesthesiologists in terms of postoperative complications. Untreated patients have an increased incidence of difficult intubations, ambulatory surgical admissions, and prolonged hospital stay.
The American Society of Anesthesiologists (ASA) has developed a screening tool for presurgical testing to identify patients at risk for OSA. This questionnaire, STOP-BANG, identifies patient history items, as well as significant physical assessment characteristics that place the patient at high risk for OSA (see The STOP-BANG questionnaire).
Those patients diagnosed with OSA or identified as high risk during presurgical testing will need additional attention during the perioperative period. During the presurgical assessment, patients with a diagnosis of OSA will be instructed to continue the use of their continuous positive airway pressure (CPAP) equipment. Patients identified as high risk will be instructed to ask their primary care provider for a possible referral to a sleep center for evaluation. A determination must be made as to whether the planned surgery will be performed on an inpatient or outpatient basis.
Intraoperatively, the considerations include choice of anesthesia, airway management, and monitoring. For superficial procedures, local or regional anesthesia rather than general anesthesia decreases the risk of postoperative complications. General anesthesia with a secure airway is preferred to deep sedation without a secure airway. Continuous monitoring of capnography should be performed during the procedure. The patient should be extubated when fully awake to decrease the incidence of airway collapse. The position of the patient for the extubation and recovery should be in the semiupright or lateral positions because remaining supine increases the incidence of complications.
In the postanesthesia care unit (PACU), the concerns for patient care include analgesia, oxygenation, positioning, and monitoring. Again, regional analgesia should be considered to decrease the need for systemic opioids for pain control. Sedatives, benzodiazepines, and barbiturates increase the risk of airway obstruction; these agents must be used with caution. Supplemental oxygen should be administered until the patient can maintain normal oxygen saturation while breathing room air. OSA patients should be placed in a nonsupine position throughout the recovery period, with continuous pulse oximetry monitoring.
Diagnosed OSA patients, who had previously been instructed to bring their CPAP equipment with them to the procedure suite, will have that equipment in place in the PACU. The stay in the PACU will be extended for a minimum of 3 hours. The need for emergency airway equipment should be anticipated and be present in the PACU. If the patient experiences a hypoxic episode, monitoring continues for 7 hours in the PACU.
Temperatures are rising
MH is a serious complication of general anesthesia. This potentially fatal condition usually occurs without warning and requires immediate, competent responses from the perioperative team to adequately treat the patient. Susceptible individuals experience a response triggered by commonly used general anesthetics and muscle relaxants.
The condition appears to be an inherited dominant trait related to muscle physiology. This genetic deficiency results in interference with calcium's reentry into the sarcoplasmic reticulum, resulting in cellular hypermetabolism. MH occurs in all racial groups and more frequently in individuals between ages 3 and 30. After puberty, the syndrome is seen more frequently in men. The incidence of occurrence is 1 in 15,000 in children and 1 in 50,000 in adults.
Patient history is an important component of identifying the syndrome. Patient or family history of adverse anesthesia events should be identified. However, 50% of patients who experience an MH crisis have previously undergone an anesthetic without incident. Other risk factors include patient or family history of perioperative fever or muscle rigidity, elevated temperature during exercise, intolerance to caffeine, myalgia on exercise, and strabismus. A history of muscle disease, such as Duchenne muscular dystrophy, myotonia, or unusual myopathies, is also a risk for MH.
Diagnostic tests for MH are infrequently used. The most accurate test, the halothane-caffeine contracture test, involves a muscle biopsy from the thigh. This is generally reserved for families who've experienced an episode of MH. The test is available at only a few centers in the United States and Canada, with limited access.
When a patient with a significant history indicating a risk of MH is identified, the perioperative staff must prepare before the procedure. The detailed MH plan, which is reviewed annually, should be reviewed before caring for the patient. Alternative anesthetic choices should be explored. Preoperative lab values, such as creatinine kinase, should be obtained as a baseline.
Anesthetic vaporizers are removed to eliminate the presence of residual inhalation agents within the anesthesia machine. The anesthesia machine is flushed with oxygen to eliminate residual inhalation agents. The carbon dioxide (CO2) absorbent on the anesthesia machine is replaced. This is important because high levels of expired CO2 that occur as part of an MH crisis cause this device to change color. A fresh canister allows the anesthesiologist to evaluate the rate of color change. A hypothermia blanket is placed on the OR table in case it's needed to control temperature. Intraoperatively, the patient will be closely monitored, including vital signs and core temperature.
MH generally manifests in the OR, but can occur postoperatively in the PACU. Early diagnosis and initiation of appropriate treatment are important for a positive outcome. Clinical manifestations of MH result in muscle rigidity, hypercarbia, tachypnea, hypoxia, metabolic and respiratory acidosis, cardiac dysrhythmias, and an elevation of body temperature (see Signs and symptoms of MH). Elevation of body temperature occurs at a rate of 1° to 2° C every 5 minutes. This is a late symptom of the syndrome and requires a rapid response from the perioperative team.
The earliest signs of MH are unexplained tachycardia with premature ventricular contractions and bigeminy, elevated expired end-tidal CO2, and a decrease in oxygen saturation in conjunction with muscle rigidity. These signs are particularly significant following the administration of succinylcholine, a commonly used depolarizing muscle relaxant that's a primary trigger for MH. All inhalation anesthetics, except for nitrous oxide (desflurane, enflurane, halothane, sevoflurane, isoflurane), are also considered MH triggers.
The anesthesiologist may be suspicious of MH if there's masseter muscle spasm after administration of succinylcholine, resulting in difficult intubation. In patients who are breathing spontaneously, tachypnea will occur as the patient's body attempts to blow off CO2 to correct the acidosis. The skin may feel warm to the touch and appear mottled or cyanotic. Intraoperatively, generalized muscle rigidity may cause the surgeon to experience difficulty with surgical exposure of the abdominal wall. This generalized rigidity is a definitive sign of MH and should put the emergency response team in place.
The Malignant Hyperthermia Association of the United States (MHAUS) is an organization that researches and publishes treatment guidelines for MH, as well as maintains a hotline for immediate consultation during an MH crisis. The ASA and AORN have adopted these guidelines. The MHAUS protocol for emergency management is available laminated for posting in every OR. MH requires preparedness to decrease morbidity and mortality. Surgical suites must review the proposed treatment protocol annually to be ready for a patient who manifests with the condition.
After an MH crisis is identified intraoperatively, the surgical team must respond quickly. The key points of immediate treatment include cessation of the use of any trigger agents, hyperventilation of the patient, and rapid administration of dantrolene sodium. In addition, cooling of the patient by all available routes is necessary to decrease the rising temperature. Hyperkalemia must be treated as it occurs.
The anesthesia provider will immediately stop any of the triggering agents being used for the anesthetic, including all inhalation agents. The patient will be ventilated with 100% oxygen to help correct hypoxemia and respiratory acidosis. The surgeon will quickly bring the surgical procedure to an end. The administration of dantrolene sodium I.V. 2.5 mg/kg will block calcium release from cells to stop the hypermetabolism.
The perioperative team will initiate surface cooling and assist with central cooling, including irrigation of the bladder with iced normal saline solution via a catheter and the stomach by way of a nasogastric tube. Iced I.V. fluids will also be administered. Ice packs will be applied to the groin and axilla. Arterial blood gases will be monitored to determine metabolic acidosis that can be treated with sodium bicarbonate. Diuretics and fluids will be administered to help flush the myoglobin out of the renal tubules to preserve the kidneys. Electrolytes are also monitored, especially potassium.
Monitoring of circulation will include insertion of arterial lines. Arrhythmias that may present will be treated according to standard advanced cardiac life support protocol.
The patient is transferred to the PACU or surgical ICU as soon as the procedure can be terminated and he or she is stabilized. Dantrolene I.V. 1 mg/kg is administered every 4 to 6 hours and continued for 24 to 48 hours after an acute episode. The patient information is sent to the North American MH Registry of the MHAUS. The MHAUS should be contacted for subsequent referral for the patient. The patient may also be sent to a center for muscle biopsy.
The key to successful treatment of MH is early identification of and rapid response to the condition. OR suites commonly have an MH cart, with all supplies needed for a rapid response available (see MH kit). This cart includes all monitoring supplies, lab tubes, dantrolene sodium, and the MHAUS protocol. In addition, I.V. and irrigation normal saline solution is kept in the refrigerator within the suite. Preparation, annual review of the MH protocol, and teamwork can make this rare but serious condition one that can be dealt with.
To a safe and successful journey!
Surgical procedures are often categorized by purpose, degree of urgency, and degree of risk. Guiding a patient safely through surgery requires an awareness of the potentially lethal complications surrounding the perioperative period, such as OSA and MH. The perioperative nurse must work collaboratively with the other members of the healthcare team to ensure the patient's safe journey through the perioperative period. Awareness is key to a successful and safe journey.
Signs and symptoms of MH
- Muscle stiffness or rigidity
- Hypoxia and dark blood in the operative field
- Unstable or elevated BP
- Cardiac dysrhythmias
- Changes in CO2 absorbent (temperature, color)
- Metabolic and respiratory acidosis
- Peripheral mottling, cyanosis
- Rising body temperature
- Hyperkalemia, hypercalcemia, lactic acidemia
- Elevation in creatine kinase level
A malignant hyperthermia kit contains:
- dantrolene sodium 20 mg (36 vials)
- sterile water for drug dilution
- dextrose 50%
- calcium gluconate
- sodium bicarbonate
- regular insulin
- I.V. cannulas (assorted sizes)
- I.V. administration sets
- three-way stopcocks
- central venous pressure sets
- blood collection tubes
- oxygen tubing and delivery devices
- arterial blood gas kit
- nasogastric tubes
- indwelling urinary catheter tray
- normal saline irrigation solution and I.V. fluids (normal saline solution) which are removed from the kit and kept refrigerated.