Handbook of Clinical Anesthesia
Preoperative Patient Assessment and Management
The goals of preoperative evaluation are to reduce patient risk and the morbidity of surgery, as well as to promote efficiency and reduce costs (Hata TM, Moyers JR: Preoperative patient assessment and management. In Clinical Anesthesia. Edited by Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC. Philadelphia: Lippincott Williams & Wilkins, 2009, pp 567–597).
- The Joint Commission requires that all patients receive a preoperative anesthetic evaluation.
- The American Society of Anesthesiologists (ASA) approved its Basic Standards for Preanesthetic Care, which outlines the minimum requirements for a preoperative evaluation.
- Conducting a preoperative evaluation is based on the premise that it will modify patient care and improve outcome.
- Based on the history and physical examination, the appropriate laboratory tests and preoperative consultations should be obtained.
- Guided by the history and physical examination, the anesthesiologist should choose the appropriate anesthetic and care plan.
- Changing Concepts in Preoperative Evaluation
- The first time the anesthesiologist performing the anesthetic sees the patient may be just before anesthesia and surgery. (The patient has been seen previously by others in a preoperative evaluation clinic.)
- Information technology using preoperative questionnaires and computer-driven programs has helped anesthesiologists preview upcoming patients that will be anesthetized.
III. Approach to the Healthy Patient
- The preoperative evaluation form is the basis for formulating the best anesthetic plan tailored to the patient. It should aid the anesthesiologist in identifying potential complications, as well as serve as a medico-legal document. The information obtained must be complete, concise, and legible.
- The approach to the patient should always begin with a thorough history and physical examination (may be sufficient without additional routine laboratory tests).
- The indication for the surgical procedure may also have implications on other aspects of perioperative management.
- Small bowel obstruction has implications regarding the risk of aspiration and the need for a rapid sequence induction.
- The extent of a lung resection dictates the need for further pulmonary testing and perioperative monitoring.
- Patients undergoing carotid endarterectomy may require a more extensive neurologic examination as well as testing to rule out coronary artery disease (CAD).
- The ability to review previous anesthetic records is helpful in detecting the presence of a difficult airway, a history of malignant hyperthermia, and the individual's response to surgical stress and specific anesthetics.
- The patient should be questioned regarding any previous difficulty with anesthesia and other family members having difficulty with anesthesia. (History relating an “allergy” to anesthesia should make one suspicious of malignant hyperthermia.)
- The history should include a complete list of medications, including over-the-counter and herbal products, to define a preoperative medication regimen, anticipate potential drug interactions, and provide clues to underlying disease.
Table 23-1 Components of the Airway Physical Examination
- Systems Approach
- Evaluation of the airway involves determination of the thyromental distance; the ability to flex the base of the neck and extend the head; and examination of the oral cavity, including dentition (Table 23-1).
- The Mallampati classification has become the standard for assessing the relationship of the tongue size relative to the oral cavity, although by itself the Mallampati classification has a low positive predictive value in identifying patients who are difficult to intubate (Table 23-2).
- In appropriate patients, the presence of pain or symptoms of cervical cord compression on movement should be assessed. In other instances, radiographic examination may be required.
Table 23-2 Airway Classification System
- Pulmonary(Table 23-3)
- Cardiovascular System(Table 23-4)
- Neurologic System.The patient's ability to answer health history questions practically ensures a normal mental status (exclude the presence of increased intracranial pressure, cerebrovascular disease, seizure history, pre-existing neuromuscular disease, or nerve injuries).
- Endocrine System.The patient should be screened for endocrine diseases (diabetes mellitus, adrenal cortical suppression) that may affect the perioperative course.
Table 23-3 Screening Evaluation for the Pulmonary System
Table 23-4 Screening Evaluation for the Cardiovascular System
- Evaluation of the Patient With Known Systemic Disease
- Cardiovascular Disease
- The goals are to define risk; determine which patients will benefit from further testing; devise an appropriate anesthetic plan; and identify patients who will benefit from perioperative beta-blockade, intervention therapy, or even surgery (Table 23-5).
Table 23-5 American Society of Anesthesiologists PhysicalStatus Classification
- Independent predictors of complications in the Goldman risk index include high-risk type of surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, preoperative treatment with insulin, and preoperative serum creatinine above 2.0 mg/dL.
- The presence of unstable angina has been associated with a high perioperative risk of myocardial infarction (MI).
- The presence of active congestive heart failure before surgery is associated with an increased incidence of perioperative cardiac morbidity.
- The importance of the intervening time interval between an acute MI and elective surgery (traditionally 6 months or longer) may no longer be valid in the current era of interventional therapy (Table 23-6).
Table 23-6 Clinical Predictors of Increased Perioperative Cardiovascular Risk (Myocardial Infarction, Congestive Heart Failure)
- Patients with Coronary Artery Disease
- For patients without overt symptoms or history, the probability of CAD varies with the type and number of atherosclerotic risk factors present (peripheral arterial disease, diabetes mellitus [autonomic neuropathy the best predictor of silent CAD], hypertension [left ventricular hypertrophy], atherosclerosis associated with tobacco use, hypercholesterolemia).
- Although there has been a suggestion in the literature that surgery should be delayed if the diastolic pressure is 110 mm Hg or above, the study often quoted as the basis for this determination demonstrated no major morbidity in that small group of patients.
- Other authors state that there is little association between blood pressures of less than 180 mm Hg systolic or 110 mm Hg diastolic and postoperative outcomes (such patients are prone to perioperative myocardial ischemia, ventricular dysrhythmias, and lability in blood pressure).
- Importance of Surgical Procedure(Table 23-7)
Table 23-7 Cardiac Risk Stratification for Noncardiac Surgical Procedures
- The surgical procedure influences the scope of preoperative evaluation required by determining the potential range of physiologic flux during the perioperative period.
- Peripheral procedures performed as ambulatory surgery are associated with an extremely low incidence of morbidity and mortality.
- High-risk procedures include major vascular, abdominal, thoracic, and orthopedic surgery.
- Importance of Exercise Tolerance
- Exercise tolerance is one of the most important determinants of perioperative risk and the need for further testing and invasive monitoring.
- An excellent exercise tolerance, even in patients with stable angina, suggests that the myocardium can be stressed without failing.
- If a patient can walk a mile without becoming short of breath, the probability of extensive CAD is small.
- If patients experience dyspnea associated with chest pain during minimal exertion, the probabil-ity of extensive CAD is high, which has been associated with greater perioperative risk.
- There is good evidence to suggest that minimal additional testing is necessary if the patient has good exercise tolerance.
- Indications For Further Cardiac Testing (Fig. 23-1)
No preoperative cardiovascular testing should be performed if the results will not change the perioperative management.
- Cardiovascular Tests
- Abnormal Q waves in high-risk patients are highly suggestive of a past MI. (It is estimated that approximately 30% of MIs occur without symptoms and can only be detected on routine electrocardiograms [ECGs].)
- The presence of Q waves on a preoperative ECG in a high-risk patient, regardless of symptoms, should alert the anesthesiologist to an increased perioperative risk and the possibility of active ischemia.
Figure 23-1. Algorithm proposed by the American Heart Association/American College of Cardiology Task Force on Perioperative Evaluation of Cardiac Patients Undergoing Noncardiac Surgery for decisions regarding the need for further evaluation. CHF = congestive heart failure; ECG = electrocardiography; MET = metabolic equivalent. (Adapted with permission from Eagle K, Brundage B, Chaitman B, et al: Guidelines for perioperative cardiovascular evaluation of noncardiac surgery. A report of the American Heart Association/American College of Cardiology Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures.Circulation 93:1278, 1996.)
- It has not been established that information obtained from the preoperative ECG affects clinical care.
- Although controversy exists, current recommendations for a resting 12-lead preoperative ECG include patients with at least one clinical risk factor who are undergoing a vascular surgical procedure and for patients with known CAD, peripheral vascular disease, or cerebrovascular disease who are undergoing intermediate-risk surgical procedures.
- Noninvasive Cardiovascular Testing
- The exercise ECG represents the most cost effective and least invasive method of detecting ischemia.
- Pharmacologic stress thallium imaging is useful in patients who are unable to exercise.
- In patients who cannot exercise, dopamine can be used to increase myocardial oxygen demand by increasing heart rate and blood pressure.
- The ambulatory ECG (Holter monitoring) provides a means of continuously monitoring the ECG for significant ST-segment changes before surgery.
- Stress echocardiography may be of value in evaluating patients with suspected CAD.
- Dobutamine echocardiography has been found to have among the best predictive values.
- Current recommendations are that patients with active cardiac conditions (unstable angina, congestive heart failure, arrhythmias, valve disease) should undergo noninvasive testing before noncardiac surgery.
- Assessment of Ventricular and Valvular Function
- Both echocardiography and radionuclide angiography may assess cardiac ejection fraction at rest and under stress, but echocardiography is less invasive and is also able to assess regional wall motion abnormalities, wall thickness, valvular function, and valve area.
- Conflicting results exist regarding the predictive value of ejection fraction determinations.
- It is reasonable for those with dyspnea of unknown origin and for those with current or prior heart failure with worsening dyspnea to
have preoperative evaluation of left ventricular function.
- Aortic stenosis has been associated with a poor prognosis in noncardiac surgical patients, and knowledge of valvular lesions may modify perioperative hemodynamic therapy.
- Coronary angiographyis the best method of defining coronary artery anatomy. (Narrowing of the left main coronary artery may be associated with a greater perioperative risk.)
- Perioperative Coronary Interventions
- The long-term survival of some patients scheduled for high-risk surgery may be enhanced by revascularization (transluminal coronary angioplasty, coronary stent placement).
- Early surgery after coronary stent placement has been associated with adverse cardiac events. Antiplatelet therapy (aspirin, clopidogrel) requires perioperative management to balance the risk of bleeding versus stent thrombosis. The risk of regional versus general anesthesia is a consideration in the presence of antiplatelet therapy.
- Pulmonary Disease
- The site and type of surgery (thoracic and upper abdominal surgery) are the strongest predictors of pulmonary complications.
- Diaphragmatic dysfunction occurs despite adequate analgesia and is theorized to be caused by phrenic nerve inhibition.
- Duration of anesthesia is a well-established risk factor for postoperative pulmonary complications, with morbidity rates increasing after 2 to 3 hours.
- Patient-Related Factors
- Preoperative evaluation of patients with pre-existing pulmonary disease should include assessment of the type and severity of disease, as well as its reversibility.
- Inquiries should be made regarding exercise intolerance, chronic cough, and unexplained dyspnea.
- On physical examination, findings of wheezing, rhonchi, decreased breath sounds, dullness to percussion, and a prolonged expiratory phase are important.
- Tobaccois an important risk factor but usually cannot be influenced. Cessation of smoking for 2 days may decrease carboxyhemoglobin levels, abolish nicotine's effects, and improve mucous clearance, but smoking cessation for at least 8 weeks is necessary to reduce the rate of postoperative pulmonary complications.
- Frequent use of bronchodilators, hospitalizations for asthma, and the requirement for systemic steroids are all indicators of the severity of the disease.
- After an episode of asthma, airway hyperreactivity may persist for several weeks.
- The possibility of adrenal insufficiency is another concern in patients who have received more than a “burst and taper” of steroids in the previous 6 months.
- Obstructive sleep apnea (OSA)(periodic obstruction of the upper airway during sleep leading to episodic oxygen saturation and hypercarbia, chronic sleep deprivation, and daytime somnolence) is estimated to be present (often undiagnosed) in 9% of females and 24% of males (Table 23-8). Preoperative identification of these patients may lead to a formal sleep study to identify the severity of symptoms and the need for preoperative initiation of continuous positive airway pressure (CPAP). A general consensus exists that preoperative institution of CPAP reduces perioperative risk.
- Patients with OSA are exquisitely sensitive to the respiratory depressant effects of inhaled anesthetics, sedatives, and opioids.
- The ASA has published practice guidelines for the perioperative management of patients with OSA.
During the preoperative evaluation, specific questions may be asked to determine the patient's likelihood of having OSA (Table 23-9).
Table 23-8 Factors Commonly Associated with an IncreasedRisk of Obstructive Sleep Apnea
Table 23-9 Questions to Ask During the Preoperative EvaluationRegarding the Presence of Symptoms and Signs of Obstructive Sleep Apnea
- Preoperative communication between the surgeon and anesthesia professional is important for planning the management of a patient with OSA (Table 23-10).
- Postoperative hospitalization is recommended for OSA patients with other coexisting diseases. When procedures are performed on an outpatient basis, postoperative monitoring (pulse oximetry) should be continued to ensure that the patient is able to maintain room air saturation without obstruction when left undisturbed.
Table 23-10 Management Decisions in Coordination with the Surgeon for Patients with Obstructive Sleep Apnea
VII. Endocrine Disease
- Diabetes mellitusis the most common endocrinopathy (0.4% of the US population has type 1, and 8% to 10% of the US population has type 2). This incidence increases increasing with the greater incidence of obesity. Critical illness–induced hyperglycemia (blood glucose >200 mg/dL) in the absence of known diabetes occurs frequently, especially in elderly individuals.
- Individuals with diabetes have an increased risk of developing CAD (silent angina caused by diabetic neuropathy), perioperative MI, hypertension, and congestive heart failure.
- Peripheral neuropathies (documented preoperatively) and vascular disease make patients with diabetes at risk for positioning injuries.
- Autonomic neuropathy is common and may contribute to hemodynamic instability and pulmonary aspiration from gastroparesis.
- Stiff joint syndrome caused by glycosylation of proteins may contribute to limited motion of the temporomandibular joint and cervical vertebra, leading to difficult airway management (this should be evaluated preoperatively).
- Patients with type 1 diabetes must receive exogenous insulin to avoid development of ketoacidosis.
- Elective surgery should be delayed if there is evidence of suboptimal blood glucose control (hemoglobin A1c >6% to 8%, abnormal electrolytes, ketonuria).
- Administration of perioperative beta-blockers (no evidence of drug-induced glucose intolerance or masking of hypoglycemic symptoms) should be considered in diabetic patients with CAD to help limit perioperative myocardial ischemia.
- Preoperative Glucose Management.Evidence is lacking to be able to set standards for the perioperative management of diabetic patients, but at a minimum, an attempt should be made to control the glucose level within a range of 100 to 200 mg/dL (some argue for a top limit of 150 mg/dL) (Table 23-11).
- Adrenal Disorders.There is consensus that for patients taking corticosteroids for long periods that perioperative steroid supplementation is indicated to cover the stresses of anesthesia and surgery.
Table 23-11 Recommendations for Perioperative GlucoseManagement in Diabetic Patients
VIII. Other Organ Systems
- Renal disease has important implications for fluid and electrolyte management, as well as metabolism of drugs.
- Liver disease is associated with altered protein binding and volume of distribution of drugs, as well as coagulation abnormalities (this may influence the choice of regional anesthesia).
- Musculoskeletal disorders have been associated with an increased risk of malignant hyperthermia.
- Osteoarthritis may result in difficulty exposing the glottic opening for tracheal intubation or difficulty in positioning the patient for regional anesthesia.
- Perioperative Laboratory Testing
- The Value of Preoperative Testing: Normal Values
- The vast majority of tests only increase or decrease the probability of disease.
- To determine the clinical relevance, a test must be interpreted within the context of the clinical situation. (There is a high incidence of false-positive test results when tests are performed in normal patients.)
- Risks and Costs versus Benefits
- The use of medical testing is associated with significant cost, both in real dollars and in potential harm to the patient.
- Even if testing better defines a disease state, the risks of any intervention based on the results may outweigh the benefit.
- Recommended Laboratory Testing(Table 23-12)
- Complete Blood Count and Hemoglobin Concentration.
- The current recommendations of the National Blood Resource Education Committee is that a hemoglobin of 7 g/dL is acceptable in patients without systemic disease.
- In patients with systemic disease, signs of inadequate systemic oxygen delivery (tachycardia, tachypnea) are an indication for transfusion.
- The only consensus is the lack of routine testing in asymptomatic adults, although creatinine and glucose testing have been recommended in older patients.
- In patients with systemic diseases and those taking medications that affect the kidneys, blood urea nitrogen and creatinine testing are indicated.
- Coagulation Studies
- Patients with abnormal laboratory study results but without clinical abnormalities rarely have perioperative problems.
- A prothrombin and partial thromboplastin time analysis are indicated in the presence of previous bleeding disorders (after injuries; after tooth extraction or surgical procedures; and in patients with known or suspected liver disease, malabsorption or malnutrition, and taking certain medications such as antibiotics or chemotherapeutic agents).
- Pregnancy Testing.Regarding the need to routinely test women without a pregnancy history, current practice varies dramatically among centers and anesthesiologists and may be a function of the population served.
Table 23-12 Recommended Laboratory Testing
- Chest Radiography
- Preoperative chest radiography may identify abnormalities that may lead to delay or cancellation of the planned surgical procedure or modification of perioperative care.
- Routine testing in a population without risk factors can lead to more harm than benefit.
- Preoperative chest radiography is indicated in patients with a history or clinical evidence of active pulmonary disease and may be indicated routinely only in patients with advanced age.
- Pulmonary function testscan be divided into spirometry and an arterial blood gas (ABG) analysis.
- With the advent of pulse oximetry, the use of preoperative ABG sampling has become less important.
- A normal serum bicarbonate level virtually excludes the diagnosis of CO2retention.
- Preoperative Medication
Preoperative Medication consists of psychological and pharmacologic preparation of patients before surgery. Ideally, all patients should enter the preoperative period free from apprehension, sedated but easily arousable, and fully cooperative.
- Psychological preparationis provided by the preoperative visit and interview with the patient and family members serving as a nonpharmacologic antidote to apprehension (Table 23-13).
- Pharmacologic Preparation
- Drugs selected for preoperative medication are administered orally with up to 150 mL of water 1 to 2 hours before the anticipated induction of anesthesia. Drugs may be administered intramuscularly (IM)
if the oral route of administration is not judged to be effective or possible. Alternatively, drugs may be administered intravenously (IV) in the immediate preoperative period.
Table 23-13 Areas to be Discussed During a Preoperative Interview
Table 23-14 Goals for Preoperative Medication
- Various Goals for Pharmacologic Premedication(Table 23-14)
- Determinant of Drug Choice and Dose(Table 23-15)
- Several classes of drugs are available to facilitate achievement of the desired individual goals for pharmacologic premedication (Table 23-16).
- There is no best drug or drug combination for preoperative medication.
- The choice may be influenced by tradition and the anesthesiologist's previous experience.
- Timing of drug delivery is as important as drug selection.
Table 23-15 Determinant of Drug Choice and Dose
Table 23-16 Drugs Used for Pharmacologic Premedication
- Ideally, the specific drugs selected are based on the goals of premedication balanced against the potential undesirable effects these drugs may produce. It is important to recognize that some patients (e.g., elderly patients and those with decreased level of consciousness, intracranial hypertension, severe pulmonary disease, or profound hypovolemia) may not need or should not receive depressant drugs for preoperative medication.
- Benzodiazepinesact on specific brain receptors (γ-aminobutyric acid) to produce selective antianxiety effects at doses that do not produce excessive sedation, depression of ventilation, or adverse cardiac effects.
- Lorazepamproduces intense amnesia, but sedation and prolonged duration of action detract from its use for short surgical procedures and in outpatients. Peak effects after oral administration may not occur for 2 to 4 hours.
- Midazolamhas replaced diazepam in its use for preoperative medication and conscious sedation. An oral form of midazolam is particularly useful for preoperative medication in children. The incidence of side effects after administration of midazolam is low, although depression of ventilation and sedation may be greater than expected,
especially in elderly patients and when the drug is combined with other central nervous system depressants. The onset after IV administration of midazolam is in 1 to 2 minutes, and recovery occurs rapidly, reflecting this drug's poor lipid solubility and rapid distribution to peripheral receptors compared with diazepam. Furthermore, the metabolites of midazolam are not likely to be pharmacologically active. For all these reasons, midazolam should usually be administered within 1 hour of induction of anesthesia.
- Opioidsare used for preoperative medication when there is a need to provide analgesia, such as before institution of a regional anesthetic or when patients have pain owing to their surgical disease. Anesthesiologists often use a combination of an opioid, benzodiazepine, and scopolamine for preoperative medication in patients who are likely to be unusually apprehensive, as before cardiac surgery or cancer surgery. Administration of opioids has the potential to produce multiple side effects, which may be exaggerated when other depressant drugs are also included in the preoperative medication (Table 23-17).
- Morphineproduces peak effects within 45 to 90 minutes after IM injection. Inclusion of morphine in the preoperative medication decreases the likelihood that undesirable increases in heart rate will accompany surgical stimulation.
- Meperidineis often administered in combination with promethazine. Peak effects after IM injection of meperidine may be unpredictable.
Table 23-17 Side Effects of Opioids as Used for Pharmacologic Premedication
Table 23-18 Summary of Fasting Recommendations to Reduce the Risk of Pulmonary Aspiration*
- Fentanyl(which is 75 to 125 times more potent than morphine as an analgesic) may be administered IV to provide a rapid onset of preoperative analgesia.
- Gastric Fluid pH and Volume
- Despite the predictable presence of acidic fluid in the stomach at the time of induction of anesthesia, clinically significant pulmonary aspiration of gastric fluid is rare in healthy patients undergoing elective surgery. The ASA has adopted guidelines for preoperative fasting (Table 23-18).
- Maintenance of a patent airway is more important than routine pharmacologic prophylaxis in otherwise healthy patients undergoing elective surgery.
- Ingestion of clear fluids in the 2 hours preceding the induction of anesthesia does not increase gastric fluid volume. Patients who are permitted to ingest clear fluids before surgery are more comfortable than those who have fasted. Under no circumstances are solid foods permitted in the period preceding induction of anesthesia for elective surgery.
- Drugs Used to Decrease Gastric Fluid Volume and Increase Gastric Fluid pH(Table 23-19)
- Antiemeticsmay be administered in the preoperative or intraoperative period as prophylaxis against
postoperative nausea and vomiting, especially in patients considered to be at increased risk for this complication (history of vomiting, obesity, ophthalmologic or gynecologic surgery) (Table 23-20).
Table 23-19 Drugs Used to Decrease Gastric Fluid Volume and Increase Gastric Fluid pH
- Routine inclusion of anticholinergics as part of the pharmacologic premedication is not mandatory but
should be individualized based on the patient's needs and the pharmacology of the anticholinergic (Table 23-21).
Table 23-20 Antiemetics Used to Prevent or Treat Postoperative Nausea and Vomiting
Table 23-21 Comparative Effects of Anticholinergics*
- Indications for Anticholinergics(Table 23-22)
- Side Effects of Anticholinergic Drugs(Table 23-23)
- Adrenergic Agonists
- Clonidine (5 mg/kg orally as preoperative medication) produces sedation, decreases the anesthetic requirements for inhaled and injected drugs, and attenuates the sympathetic nervous system response (hypertension, tachycardia, catecholamine release) to tracheal intubation.
- Dexmedetomidine is a more selective α-adrenergic agonist than clonidine that has also been used for preoperative medication.
Table 23-22 Indications for Anticholinergics
Table 23-23 Side Effects of Anticholinergic Drugs
- Side effects (hypotension, bradycardia, dry mouth) limit the usefulness of these drugs for preoperative medication.
- Other Drugs Given with Preoperative Medication(Table 23-24)
- Differences in Preoperative Medication Between Pediatric and Adult Patients
- Children differ from adults regarding preoperative medication in terms of psychological preparation,
greater use of oral medications, and more frequent use of anticholinergics to reduce vagal activity.
Table 23-24 Other Drugs Given with Preoperative Medication
- Psychological Factors in Pediatric Patients
- Age is probably the most important factor in the success of a preoperative visit and interview.
- Children who do not ask questions or appear disinterested during the preoperative interview may be masking a high level of anxiety.
- Some children wish to take an active part in the induction of anesthesia. In this regard, it may be helpful to have the parents accompany these children to the operating room.
- Differences in Pharmacologic Preparation
- Use of pharmacologic premedication in children older than age 6 months is controversial and has not been proven to decrease unwanted psychological outcomes. More important in avoiding long-lasting psychological problems is a pleasant induction of anesthesia.
- Oral administration (often midazolam in a flavored liquid) is preferred to IM injections in children.
- Some anesthesiologists prefer to administer atropine IM or IV just before the induction of anesthesia to protect against vagal reflexes in response to airway manipulations.
Editors: Barash, Paul G.; Cullen, Bruce F.; Stoelting, Robert K.; Cahalan, Michael K.; Stock, M. Christine
Title: Handbook of Clinical Anesthesia, 6th Edition
Copyright ©2009 Lippincott Williams & Wilkins
> Table of Contents > Section V - Preanesthetic Evaluation and Preparation > Chapter 24 - Malignant Hyperthermia and Other Inherited Disorders