Preoperative Patient Assessment and Management
The goals of preoperative evaluation are to reduce patient risk and the morbidity of surgery and to promote efficiency and reduce costs (Hata TM, Hata JS. Preoperative patient assessment and management. In: Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Ortega R, Stock MC, eds., eds. Clinical Anesthesia. Philadelphia: Lippincott Williams & Wilkins; 2013:581–611).
I. Introduction
The Joint Commission requires that all patients receive a preoperative anesthetic evaluation. The American Society of Anesthesiologists (ASA) has published a Practice Advisory for Preanesthetic Evaluation and Basic Standards for Preanesthetic Care (www.asahq.org). 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.
II. Changing Concepts in Preoperative Evaluation
The first time the anesthesiologist performing the anesthetic sees the patient may be just before anesthesia and surgery. Information technology using preoperative questionnaires and computer-driven programs has facilitated the preoperative evaluation.
III. Approach to the Healthy Patient
The preoperative evaluation form is the basis for formulating the best anesthetic plan tailored to the patient. It aids in identifying potential complications, as well as serving as a medicolegal
document (legibility is no longer an issue with electronic medical records). The approach to the patient should always begin with a thorough history and physical examination (may be sufficient without additional routine laboratory tests).
document (legibility is no longer an issue with electronic medical records). The approach to the patient should always begin with a thorough history and physical examination (may be sufficient without additional routine laboratory tests).
Indications 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 need for a rapid sequence induction.
The extent of a lung resection will dictate 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)
Response to Previous Anesthetics
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.
Medications and Allergies. The history should include a complete list of medications, including over-the-counter and herbal products.
Systems Approach
Airway
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 22-1).
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 22-2).
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.
Pulmonary System (Table 22-3)
Cardiovascular System (Table 22-4)
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 22-1 Components of the Airway Physical Examination | ||||||||||||||||||||||||
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Table 22-2 Airway Classification System | |||||||||||||||
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Table 22-3 Screening Evaluation for the Pulmonary System | ||
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IV. 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 22-5).
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 >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 22-6).
Identifying Patients at Risk for Cardiac 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 associated with CAD).
Diabetes Mellitus. Autonomic neuropathy is the best predictor of silent CAD.
Hypertension. Hypertensive patients with left ventricular hypertrophy and undergoing noncardiac surgery are at a higher perioperative risk than nonhypertensive patients.
Although there has been a suggestion in the literature that surgery should be delayed if the diastolic pressure is ≥110 mm Hg, the study often quoted as the basis for this determination demonstrated no major morbidity in that small group of patients.
Other Risk Factors. Tobacco use and hypercholesterolemia increase the probability of developing CAD but have not been shown to increase perioperative cardiac risk.
Importance of Surgical Procedure (Table 22-7)
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 probability of extensive CAD is high, which has been associated with a greater perioperative risk.
There is good evidence to suggest that minimal additional testing is necessary if the patient has good exercise tolerance.
Table 22-4 Screening Evaluation for the Cardiovascular System | |||||||||
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Table 22-5 American Society of Anesthesiologists Physical Status Classification | ||||||||||||||
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Table 22-6 Clinical Predictors of Increased Perioperative Cardiovascular Risk (Myocardial Infarction, Congestive Heart Failure) | ||||
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Table 22-7 Cardiac Risk Stratification for Noncardiac Surgical Procedures | |||
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V. Indications for Further Cardiac Testing
No preoperative cardiovascular testing should be performed if the results will not change the perioperative management.
Cardiovascular Tests
Electrocardiography
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.
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.Related posts:
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