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Preoperative Evaluations


The preoperative evaluation of the patient undergoing anesthesia is both a requirement of the Centers for Medicare and Medicaid Services and important in preparing an anesthetic plan. Certain parts of the anesthesia preoperative evaluation are standard, whereas other elements are individualized depending on the patient, timing of the evaluation, type of procedure, and location. Non–operating room procedures requiring anesthesia (NORA) present a unique set of challenges for the anesthesiologist. The anesthesiologist experiences pressure to evaluate the patient with limited information, start the procedure in a location where emergency equipment is not readily accessible, and provide an anesthetic that will allow for a short recovery period in a busy procedural suite. Although commonalities exist in the preoperative evaluation of patients regardless of their American Society of Anesthesiologists (ASA) classification ( Table 9-1 ), many parts of the evaluation depend on a patient’s comorbidities and symptoms and the location of the planned procedure.

Table 9-1
American Society of Anesthesiologists Physical Status Classification ∗
From American Society of Anesthesiologists. http://www.asahq.org .
ASA 1 Normal healthy patient
ASA 2 Patient with mild systemic disease
ASA 3 Patient with severe systemic disease
ASA 4 Patient with severe systemic disease that is a constant threat to life
ASA 5 Moribund patient who is not expected to survive without the operation
ASA 6 Declared brain-dead patient whose organs are being removed for donor purposes

∗ An “E” classification added to the ASA status indicates emergency surgery.

When patients have routine medical care, their comorbidities are known and properly managed. Other patients, however, present on the day of the procedure without diagnoses or with symptoms that may be serious enough to require further evaluation. The severity of the symptoms and the urgency of the procedure determine whether additional testing is required. It is the anesthesiologist’s responsibility to obtain a patient medical history, perform a physical examination, and decide with the proceduralist and patient how to best proceed.

Procedures outside the operating room are challenging for the anesthesiologist because emergency equipment such as the airway cart, defibrillator, and transducer for an arterial line need to be planned for and obtained ahead of time. Nonanesthesia personnel in NORA locations may not be accustomed to the patient preparations needed by the anesthesiologist. Skilled anesthesia personnel may be far away from the procedure room. Recovery room personnel are often not familiar with caring for a patient recovering after a general anesthetic. The goals of the anesthesiologist, proceduralist, and staff are to provide the patient with the safest, highest quality care in a way that is compassionate and efficient. A thorough preoperative evaluation by the anesthesiologist helps caregivers prepare for potential complications such as a difficult airway or prolonged recovery. Contingency plans should be communicated among practitioners so that challenges can be anticipated rather than unexpected.

Preoperative Assessment

To begin, it is important to address the standard elements of the preoperative assessment—a discussion with the patient or guardian to review the medical, medication, and anesthesia history and a physical examination focused on the airway, heart, and lungs. Diagnostic studies, previous anesthetics, laboratory values, and consultation reports are routinely reviewed during this assessment. On the basis of this information an ASA physical status is assigned to the patient. After reviewing and obtaining all the information, the anesthesiologist creates the anesthetic plan and then discusses it with the proceduralist and patient.

It is useful to have a mechanism to obtain patient-specific information. This can be a standardized form that documents the patient’s medical history online or on paper ( Figure 9-1 ). The form can guide the anesthesiologist in completing the assessment and focuses on comorbidities, current medications, allergies, previous surgical and anesthetic history, and use of alcohol, tobacco, or other illicit substances. If the patient does not know the medications currently taken, a phone call to the patient’s pharmacy can provide this information. With this medication list, other elements of the patient’s medical history can be deciphered. A review of systems with questions pertinent to cardiovascular, pulmonary, or neurologic symptoms completes the necessary evaluation. A targeted interview can subsequently concentrate on elucidating comorbidities pertinent to anesthesia care, their severity, frequency of exacerbations, and previous and current management. The interviewer will determine the patient’s functional capacity ( Table 9-2 ) and assign the patient an ASA physical status classification that can stratify periprocedural risk. A better cardiopulmonary reserve as evidenced by a metabolic equivalent (MET) greater than 4 or 5 predicts a lower risk for perioperative complications. Complications during previous anesthetics or any family complications with anesthesia are reviewed. Certain complications are more difficult to treat in NORA locations, where resources such as postoperative ventilator support are typically unavailable and the patient may need monitored transport to the nearest phase I postoperative anesthesia care unit.

Figure 9-1, Patient medical history.

Table 9-2
Metabolic Equivalents of Functional Capacity Measured 1 Through 12
From Jette M, Blumchen G. Metabolic equivalents (METS) in exercise testing, exercise prescription, and evaluation of functional capacity. Clin Cardiol. 1990;13(8):555-565.
Eating, working at computer, getting dressed 1 ∗
Walking down stairs at home, cooking 2
Walking 1-2 blocks 3
Gardening, raking leaves 4
Climbing one flight of stairs, cycling, dancing 5
Carrying clubs while playing golf 6
Playing singles tennis 7
Climbing stairs quickly, slow jogging 8
Moderate cycling, jumping rope slowly 9
Running, or swimming quickly 10
Cross-country skiing, playing basketball using a full court 11
Rapidly running for long distances 12

∗ One metabolic equivalent (MET) is equivalent to the consumption of 3.5 mL O 2 /min/kg.

Physical Examination

During the physical examination, attention is given to the patient’s venous vasculature to assess how quickly or easily access can be obtained. If an abnormality is found on routine auscultation of the heart and lungs, a consultation, call to the patient’s cardiologist or pulmonologist, or further work may be necessary. Based on the information obtained in the interview, a more detailed examination may follow. For example, if a patient has had a stroke, a residual neurological deficit is documented. The airway examination is critical to the preoperative assessment. The Mallampati type found on the physical examination will help determine if an airway has the potential for a difficult intubation. If a difficult airway is anticipated, preparations must be made in advance. Other pertinent elements of the airway examination appear in Box 9-1 .

Box 9-1
Elements of the Airway Examination
From Kheterpal, S, Han R, Tremper K, et al. Incidence and predictors of difficult and impossible mask ventilation. Anesthesiology. 2006;105(5):885-891.

  • Cervical spine: Limited extension, limited flexion, known or possible unstable

  • Neck anatomy: Limited laryngeal mobility, mass, radiation changes, thick or obese, tracheal deviation

  • Thyroid cartilage to mentum distance: <6 cm, ≥6 cm

  • Mouth opening interincisor or intergingival distance: <3 cm, ≥3 cm

  • Mandibular protrusion test

  • Mallampati classification: I, II, III, or IV

  • Full beard or mustache

  • Dentition: Normal, dentures or partials, edentulous, missing or broken teeth

  • History of cough

  • History of rhinorrhea

  • History of chronic obstructive pulmonary disease; treatment with steroids or bronchodilators

  • History of asthma

  • History of nightly snoring

  • History of obstructive sleep apnea requiring continuous positive airway pressure, bilevel positive airway pressure, or surgery

Although anesthesiologists often have to make treatment decisions with only partial information available, the preoperative assessment should not be abbreviated because the anesthetic is being delivered in a NORA location. The assessment still must be thorough, even for a minor procedure with monitored anesthesia care. Any procedure or anesthetic has the potential for complications and may require conversion to a general anesthetic. In NORA locations, the paucity of resources makes planning for contingencies for even a minor procedure important.

Preoperative Evaluations

If a patient with a history of syncope previously not evaluated is to undergo a colonoscopy, should the procedure continue as planned? It depends on whether the case is elective or emergent, if there is a likely explanation for the syncope, or other factors. If the case is emergent or the syncope is not likely due to continued pathological issues, the anesthesiologist may choose to proceed and will take precautions for problems such as arrhythmias. If the case is elective, further evaluation of the syncope is warranted before proceeding, if there is any doubt to the precipitating cause.

Certain comorbidities require evaluation before an anesthetic is administered. Ischemic heart disease is common and associated with increased risk during anesthesia and certain procedures. Patients may have diagnosed and well-managed ischemic heart disease or symptoms suggestive of coronary artery disease (CAD) that have not been evaluated. Should the procedure proceed as planned? The American College of Cardiology Foundation and American Heart Association (ACC/AHA) have recommendations for testing and revascularization ( Figure 9-2 ). The anesthesiologist should stop at the first part of the algorithm that applies to the patient. For an emergency procedure such as thrombolytic therapy for an acute stroke, the focus is on risk reduction with beta-adrenergic blockers, statins, and perioperative surveillance with serial electrocardiograms (ECG), enzyme levels, and monitoring. An emergent procedure should not be delayed for further testing. However, if the case is not emergent, a procedure should be postponed to have a patient’s active cardiac condition stabilized or corrected. Active cardiac conditions include unstable angina, acute or recent myocardial infarction if other myocardium is at risk, decompensated heart failure, significant arrhythmias, or severe valvular disease. A patient without active cardiac symptoms who is undergoing a low-risk procedure proceeds without further testing. If the patient has a MET greater than 4 and is asymptomatic or stable, no additional testing is required, because the majority of NORA procedures would be considered low-risk procedures.

Figure 9-2, Cardiac evaluation algorithm.

Coexisting Diseases

Coronary Artery Disease

Patients with CAD are managed with medication regardless of whether they have had cardiac stenting or coronary artery bypass grafting. Evidence supports long-term benefits of statins and aspirin in all patients with vascular disease. Patients who have had a myocardial infarction benefit from beta-adrenergic blocking drugs unless contraindicated. These drugs typically need to be continued in the perioperative period, although acute initiation has been associated with increased risk. See the section on medications for a detailed discussion.

Heart Failure

Heart failure is associated with risk for perioperative complications. Patients with heart failure may have fatigue, recent weight gain, dyspnea, orthopnea, or peripheral edema. Some patients may have new-onset heart failure, an exacerbation that needs additional evaluation, medication, or diet modification. For patients with decompensated heart failure, elective procedures are postponed until echocardiographic imaging is obtained and the patient’s status has returned to baseline. Causes of heart failure are numerous, ranging from excessive circulating volume requiring diuretic therapy, to postchemotherapy cardiomyopathy, to worsening ischemic heart disease requiring evaluation. If the patient has symptoms compatible with undiagnosed, poorly managed, or decompensated heart failure, a cardiology evaluation is recommended for optimization of the patient’s condition before the procedure. If a patient’s symptoms are not significant and are stable, minor procedures may proceed as planned.

Heart Murmurs

Certain cardiac murmurs merit evaluation. Functional murmurs from turbulent flow across valves in high-output states such as pregnancy, hyperthyroidism, and anemia are not concerning. Other murmurs may be pathological and need to be evaluated by echocardiography before an elective procedure. Valvular disease is suspected in patients with CAD, advanced age, a history of rheumatic fever, cardiomegaly, heart failure, or pulmonary disease. Some patients will report having known mitral or aortic valvular pathological conditions. The type of valvular disease may affect the choice of anesthetic technique and may necessitate advanced monitoring via arterial line or transesophageal echocardiography (TEE), which are not routinely available in NORA locations. Delineation of conditions and communication are important. For example, if severe aortic stenosis is present, spinal anesthesia is relatively contraindicated and the degree of stenosis is quantified before general anesthesia for an elective procedure. Aortic stenosis may be confused for aortic sclerosis in older patients. Both have associated systolic murmurs, but aortic sclerosis is more prevalent and is not associated with hemodynamic stability. In contrast, patients with severe or critical aortic stenosis require a cardiology evaluation before elective procedures. These patients may be best managed by moving to an operating room setting where advanced support is available. If the case necessitates being done in NORA location, an anesthesiologist who can transport and use a TEE may be requested for the case.

Antibiotic Prophylaxis

Guidelines by the American Heart Association that designate who requires antibiotic prophylaxis against infective endocarditis appear in Boxes 9-2 and 9-3 . Antibiotic recommendations depend on the patient’s preexisting condition and the type of procedure. For patients with native valves, antibiotic prophylaxis is not routinely recommended even if an abnormality on the native valve is present. However, if a patient has a transplanted heart with valvular abnormalities, antibiotic prophylaxis is necessary for certain procedures. For a patient with a prosthetic cardiac valve, previous infective endocarditis, unrepaired congenital heart disease, or lifelong valvular defects after repair, antibiotic prophylaxis is also necessary after certain procedures, which are listed in Box 9-3 . Antibiotic prophylaxis against infective endocarditis is no longer recommended for genitourinary and gastrointestinal procedures. For patients with abnormalities listed in Box 9-2 undergoing dental procedures that involve manipulation of gingival tissues or oral mucosa or for procedures on the respiratory tract or infected tissue, antibiotic prophylaxis is recommended.

Box 9-2
Cardiac Conditions for Which Endocarditis Prophylaxis Is Indicated
From Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association. Circulation. 2007;116(15):1736-1754.

  • Prosthetic cardiac valve or prosthetic material used for cardiac valve repair

  • Previous infective endocarditis

  • Congenital heart disease (CHD)

    • Unrepaired cyanotic CHD (palliative shunts and conduits)

    • Completely repaired congenital heart defect with prosthetic material or device, during the first 6 months after the procedure

    • Repaired CHD with residual defects

  • Cardiac transplantation recipients who develop cardiac valvulopathy

Box 9-3
Endocarditis Prophylaxis Indications
From Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association. Circulation. 2007;116(15):1736-1754.

  • Bacteremia resulting from daily activities is much more likely to cause infective endocarditis than bacteremia associated with a dental procedure.

  • Only an extremely small number of cases of infective endocarditis might be prevented by antibiotic prophylaxis even if prophylaxis is 100% effective

  • Limit recommendations for infective endocarditis prophylaxis to only those conditions listed in Box 9-2 .

  • Antibiotic prophylaxis is no longer recommended for any other form of congenital heart disease, except for the conditions listed in Box 9-2 .

  • Antibiotic prophylaxis is no longer recommended based solely on an increased lifetime risk for acquisition of infective endocarditis.

  • Antibiotic prophylaxis is not recommended solely to prevent infective endocarditis for genitourinary or gastrointestinal tract procedures.

For patients with underlying cardiac conditions associated with the highest risk for adverse outcome from infective endocarditis (see Table 9-2 ), antibiotic prophylaxis is reasonable for the following:

  • All dental procedures that involve manipulation of gingival tissues or periapical region of teeth or perforation of oral mucosa.

  • Procedures on respiratory tract or infected skin, skin structures, or musculoskeletal tissue.

Although these guidelines recommend changes in indications for infective endocarditis prophylaxis with regard to selected dental procedures, the writing group reaffirms that those medical procedures listed as not requiring infective endocarditis prophylaxis in the 1997 statement remain unchanged and extends this view to vaginal delivery, hysterectomy, and tattooing. Additionally, the committee advises against body piercing for patients with conditions listed in Box 9-2 because of the possibility of bacteremia, while recognizing minimal published data exist regarding the risk for bacteremia or endocarditis associated with body piercing.

Stents and Anticoagulation Therapy

Patients who have had percutaneous coronary intervention (PCI) should be identified before scheduling a procedure. The length of wait time before an elective noncardiac procedure after PCI is determined by the type of revascularization and the period of recommended dual antiplatelet therapy to prevent thrombosis. For PCI without stenting, 2 weeks of dual antiplatelet therapy should be completed. If a drug-eluting stent is placed, 12 months of aspirin and thienopyridine therapy (clopidogrel or ticlopidine) is required. If a bare metal stent is placed, 1 month of dual antiplatelet therapy is indicated. The patient is considered high risk during the mandated period of dual antiplatelet therapy, and elective procedures requiring cessation of antiplatelets or with a risk for bleeding are delayed. However, if a procedure mandates the discontinuation of thienopyridine therapy during the high-risk period, aspirin is continued, with a plan to restart the thienopyridine postoperatively. The preanesthetic visit offers the opportunity to identify the type of PCI and discuss the dual antiplatelet therapy with the patient’s cardiologist. Premature discontinuation of antiplatelet therapy can have catastrophic consequences, such as stent thrombosis, myocardial infarction, or even death. The patient needs to be aware of the risks of discontinuation of these drugs ( Box 9-4 ).

Box 9-4
Summary of Recommendations from the 2007 Science Advisory and the 2007 American College of Cardiology and American Heart Association
From American Society of Anesthesiologists Committee on Standards and Practice Parameters. Practice alert for the perioperative management of patients with coronary artery stents. Anesthesiology. 2009;110:22-23.

  • Premature discontinuation of dual antiplatelet therapy with new coronary stents increased risk for life-threatening stent thrombosis in the perioperative period.

  • The time period for this risk is 4 to 6 weeks for bare metal stents and 12 months for drug-eluting stents.

  • Timing of elective surgery with new coronary stents: Elective procedure should be deferred until patients complete an appropriate course of thienopyridine therapy.

  • Elective noncardiac surgery is not recommended when thienopyridine therapy or thienopyridine and aspirin therapy needs to be continued during the perioperative period.

  • The recommended period of thienopyridine therapy or thienopyridine and aspirin therapy is a minimum of 1 month or 4 to 6 weeks for bare metal stents and 12 months for drug-eluting stents.

  • If surgery cannot be deferred and thienopyridine therapy must be interrupted in patients with new coronary stents, aspirin should be continued. The thienopyridine should be restarted as soon as possible after the surgical procedure.

  • Dual antiplatelet therapy should be continued beyond the recommended time frame in any patient at high risk for stent thrombosis. Even after thienopyridine has been discontinued for a procedure, aspirin therapy should be continued perioperatively in any patient with a drug-eluting stent.

Hypertension

Patients with hypertension who are to undergo NORA procedures may have elevated blood pressure on the day of a procedure as a result of chronically poor control, anxiety, or not taking morning medications. Patients with severe hypertension commonly have comorbidities such as heart failure, renal insufficiency, ischemic heart disease, or history of stroke. The preoperative goal is to restore blood pressure to normal levels over a period of weeks before a procedure and to avoid intraoperative hypotension, which can result in an ischemic event. Aggressive lowering of blood pressure on the day of a procedure is more dangerous than hypertension. Delaying procedures for patients with severe hypertension until a blood pressure of less than 180/110 mmHg is achieved is recommended.

Cardiovascular Implantable Electronic Devices

Patients with pacemakers or implantable cardioverter-defibrillators (ICDs) have pathological arrhythmias, cardiomyopathies, or ischemic or valvular disease. The patient’s wallet card will contain pertinent information regarding the device. Electrocautery can cause an ICD to discharge or inhibit pacemakers from pacing. A patient can be inappropriately defibrillated or not be paced adequately if he or she is pacemaker-dependent. All ICDs have backup pacing capabilities. Application of a magnet on an ICD inhibits antitachycardia therapies, but does not affect the pacing function. A magnet placed over a pacemaker converts the device to asynchronous pacing for the duration of magnet application. Suggestion has been made that if electrocautery is limited to below the umbilicus, it is highly unlikely to affect a pacemaker or ICD and use of a magnet or reprogramming the device is not necessary. If it is anticipated that electrocautery will be used above the umbilicus, it is prudent to contact someone who is familiar with such devices for recommendations on the use of a magnet or whether the device requires reprogramming. A defibrillator must be immediately available to deliver antitachycardia therapy or transcutaneous pacing whenever a patient with an ICD or a pacemaker who is pacemaker-dependent is having a procedure. Magnets may permanently disable antitachycardia therapies when applied to ICDs. If a magnet is used, the device was reprogrammed, or interference from electrocautery has occurred, these devices must be reinterrogated to establish previous settings before the patient leaves a monitored setting. A summary of the potential interactions between implanted cardiac devices and various procedures is provided in Box 9-5 .

Box 9-5
Potential Problems with Cardiovascular Implantable Electronic Devices During Surgical Procedures
From Crossley GH, Poole JE, Rozner MA, et al. The Heart Rhythm Society (HRS)/American Society of Anesthesiologists (ASA) expert consensus statement on the perioperative management of patients with implantable defibrillators, pacemakers and arrhythmia monitors: facilities and patient management—executive summary. Heart Rhythm. 2011;8(7):e1-e18.

  • Bipolar electrocautery does not cause EMI unless applied directly to CIED; bipolar cautery should be used when possible.

  • EMI from monopolar electrocautery is common.

  • If monopolar cautery is used, bursts should be ≤5 seconds.

  • Pacemakers may oversense and be inhibited by EMI.

  • Device reset infrequently occurs with electrocautery.

  • Cardioversion can reset CIED.

  • Keeping the current path away from CIED decreases potential for CIED complications.

  • Gastrointestinal procedures using cautery can cause interference.

  • ECT causing tachycardia may prompt review of ICD tachycardia therapy zones.

  • TENS can cause EMI.

CIED, Cardiovascular implantable electronic device; ECT, electroconvulsive therapy; EMI, electromagnetic interference; ICD, implantable cardioverter-defibrillator; TENS, transcutaneous electrical nerve stimulation.

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