Preoperative Evaluation and Management

Cardiac Evaluation and Management

Despite optimal management of cardiovascular risk factors, major vascular surgery is associated with postoperative myocardial infarction in 1.6% of all patients, with higher risk after open abdominal aortic aneurysm repair or peripheral bypass. Postoperative myocardial infarction increases 1 year mortality from approximately 5% to 37%. In addition to a thorough cardiac history, physical examination, and baseline ECG, advanced cardiac testing may be appropriate for selected patients undergoing elective vascular procedures. The American College of Cardiology (ACC) Foundation and the American Heart Association (AHA) have provided recommendations regarding preoperative cardiac workup ( Fig. 34.1 ). Perioperative risk stratification is based on a combination of patients’ functional status and the anticipated physiologic strain of surgery. Low risk vascular procedures with anticipated <1% 30-day major adverse coronary events (MACE) include carotid endarterectomy and carotid artery stenting in asymptomatic patients. Intermediate risk vascular procedures (1%–5% MACE within 30 days) include carotid endarterectomy and carotid artery stenting in symptomatic patients, peripheral artery angioplasty, and endovascular aneurysm repair. High risk vascular procedures (>5% MACE within 30 days) include open aortic surgery, limb revascularization or amputation, and thromboembolectomy. ^, Functional capacity is measured by metabolic equivalents (METS), where one MET is the basal metabolic rate of a 70-kg, 40-year-old man. Common activities requiring 4 METS include walking less than three flights of stairs, dancing, or light housework. Athletics (e.g. basketball, weight training) require ≥10 METS. Asymptomatic patients with a functional capacity of 4–10 METS, those with a normal stress test within 2 years, and those who have had coronary revascularization within 5 years, do not need further cardiac testing. Stress testing may be indicated for patients at intermediate or high cardiac risk with poor or unknown functional capacity (<4 METs). Routine stress testing is not indicated for patients at low risk for noncardiac surgery.

Patients with a pacemaker or an implantable cardioverter-defibrillator may require reprogramming or application of a magnet over the device to prevent the transient inhibition of pacing or the inappropriate triggering of shocks if monopolar electrocautery is used. Furthermore, external defibrillation equipment with transcutaneous pacing ability should be readily available in the operating room for these patients.

Preoperative Medical Versus Interventional Therapy for Cardiac Disease

Perioperative use of beta blockers has long been the standard of care for most patients with cardiac disease undergoing vascular surgery. However, their use has engendered significant controversy during the past several years. The POISE (PeriOperative ISchemic Evaluation) trial and the Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography trial (DECREASE-IV) trials both showed some benefit to beta blockade in selected groups of vascular patients, but both trials have had their results called into question. ^{, ,} In a review of nearly 12,000 patients undergoing infrainguinal revascularization in the Vascular Quality Initiative (VQI) database, Shannon et al. showed that preoperative beta blockade was an independent predictor of 30-day MI and MACEs after controlling for other cardiovascular risk factors; there was no impact on short-term limb-related outcomes. Another systematic review by Hajindebeh et al. examining more than 32,000 patients showed no change in outcomes when beta blockers were administered in the perioperative period. In a separate systematic review, preoperative use of beta blockers was associated with a reduction of cardiac events, but support was lacking regarding the effectiveness of preoperative administration of beta blockers to reduce the risk of surgical death. Furthermore, there is a clear association between beta-blocker administration and adverse outcomes, such as bradycardia and stroke. Likewise, withdrawal of chronic beta blockade has risk, including rebound tachycardia, and the use of these medications should be guided by individual circumstances for best medical therapy based on cardiovascular risk independent of the need for vascular surgery. Thus, the best recommendation for beta-blocker use is to continue them in patients who have been on them chronically. In patients with intermediate or high risk myocardial ischemia on preoperative risk stratification tests or with three or more Revised Cardiac Risk Index (RCRI) risk factors (e.g., diabetes mellitus, heart failure, coronary artery disease, renal insufficiency, stroke), it is reasonable to begin perioperative beta blockers in advance of surgery to assess safety and tolerability. Beta-blocker therapy should generally not be started on the day of surgery.

Most other established medications should be continued throughout the perioperative period with the exception of angiotensin receptor blockers (ARBs) and angiotensin-converting enzyme inhibitors (ACEIs). There is evidence that high intensity statins reduce the risk of adverse cardiovascular events, including mortality and limb loss, among high-risk patients and patients with peripheral arterial disease through their pleiotropic effects on endothelial function, reduction in vascular inflammation, and stabilization of atherosclerotic plaque. ^, In the absence of a specific contraindication or intolerance, statins should be initiated prior to surgery and be continued throughout the perioperative period (see Ch. 44 , Systemic Complications: Cardiac).

Although many surgeons prefer to discontinue clopidogrel or other P2Y ₁₂ inhibitors due to a perceived risk of increased bleeding at the time of surgery, there are scant objective data to support this practice. Several studies demonstrate the overall safety of continuing DAPT during vascular surgery, ^, though there may be a slightly higher risk of bleeding in exchange for a reduction in cardiovascular events. ^, Furthermore, the role of dual antiplatelet therapy (DAPT) in the management of coronary artery disease continues to evolve. Current ACC/AHA guidelines support the use of DAPT following percutaneous coronary intervention (PCI) with both bare metal stents (BMSs) and drug-eluting stents (DESs). The duration of DAPT is dependent on the indication (acute coronary syndrome vs. stable angina) and PCI technique (BMS vs. DES), balanced against the estimated risk of bleeding. If the risk of surgical bleeding is believed to be high, elective vascular procedures should be postponed until DAPT can be safely withheld. If the procedure is urgent DAPT should be continued, particularly during the first 4 to 6 weeks following stent implantation, unless the risk of bleeding outweighs the risk of coronary stent thrombosis. Consultation with cardiology is appropriate prior to discontinuing DAPT (see Ch. 42 , Antiplatelet Agents).

The role of coronary revascularization prior to vascular surgery is uncertain. Generally, coronary revascularization is recommended for patients with left main coronary artery disease, three-vessel coronary disease, complex anatomy or high risk comorbidities. The Coronary Artery Revascularization Prophylaxis (CARP) trial demonstrated that in patients with stable coronary artery disease, coronary artery revascularization before elective major vascular surgery does not improve long-term cardiac outcomes or reduce short-term postoperative outcomes such as death, MI, or length of hospital stay. In addition, preoperative coronary artery revascularization in vascular patients is associated with increased risk for procedure-related complications and may lead to delay in the intended vascular procedure. Furthermore, patients with CABG or PCI <5 years prior to vascular surgery do not have a survival advantage over patients at high cardiac risk without previous coronary interventions. Therefore, ACC/AHA guidelines recommend preoperative revascularization only when it would otherwise be indicated in nonoperative situations. Only patients with unprotected left main disease (the left main trunk is unprotected when there is a >50% stenosis and the absence of at least one patent bypass to the left circumflex or left anterior descending artery) showed a benefit from preoperative coronary artery revascularization. CABG showed improved outcomes versus PCI.

Preoperative Management of Hypertension

There is no consensus on specific perioperative blood pressure targets, although higher morbidity and mortality is associated with both hypotension and hypertension. For noncardiac surgery, the strongest recommendation is for an individualized approach to each patient maintaining a blood pressure within 90%–110% of baseline. For patients with a low baseline (SBP <90 mm Hg, DBP <50 mm Hg) it is recommended to maintain a MAP ≥60 mm Hg, and for patients with a high baseline (SBP ≥130, DBP ≥80), it is recommended to maintain the SBP <160 mm Hg.

There is general consensus that chronic antihypertensive medications should be continued during the perioperative period, with the exception of ACEIs and ARBs. Withholding chronic ACEI/ARB therapy is associated with less intraoperative hypotension with no difference in all-cause death, stroke, and MI. Intraoperative hypotension in patients who receive ACEIs or ARBs on the day of surgery has been associated with an increased risk of all-cause death, stroke, and MI (see Ch. 14 , Hypertension).

Pulmonary Evaluation and Management

Pulmonary complications are reported in 1% to 2% of minor surgeries and up to 20% in upper abdominal or thoracic operations. As such, preoperative pulmonary evaluation should be completed in all patients and should begin with a history and physical examination, which is the most sensitive evaluation to identify patients at risk for complications. Risk factors for postoperative pulmonary complications include emergency procedure, age over 65 years, congestive heart failure, chronic obstructive pulmonary disease, functional status, tobacco use, operative time, ASA class ≥2, and procedure type (abdominal aortic aneurysm, thoracic, upper abdominal). The surgeon should elicit any history of smoking, oxygen dependence, exercise intolerance, unexplained dyspnea, or coughing. On physical examination, decreased breath sounds, wheezes, crackles, or a prolonged expiratory phase should be noted. Procedure-related risks should likewise be assessed. Procedural time greater than 3 hours, need for emergent surgery, and the surgical site all influence the risk of perioperative pulmonary complications. Aortic aneurysm, thoracic, abdominal, and emergency surgery all increase the risk of pulmonary complications. Obstructive sleep apnea, which is present and often undiagnosed in up to 22% of the adult population undergoing surgical procedures, increases the chances of postoperative hypoxemia and reintubation in the postoperative period.

Asymptomatic patients do not need routine preoperative chest X-rays, however a chest X-ray is recommended for patients with known cardiopulmonary disease, age >50 years, and if undergoing abdominal, thoracic, or abdominal aortic aneurysm surgery.

Several indices can be used to stratify pulmonary risk. These include factors such as the type of surgery, age, functional status, weight loss/nutritional status, COPD, smoking, whether the surgery is emergent, and obstructive sleep apnea. Obstructive sleep apnea can be screened for using the validated snoring, tiredness, observed apnea, high blood pressure, neck circumference, male sex (STOP-Bang) score. Low serum albumin (<3.5 g/L) is a powerful, independent marker of increased risk for postoperative pulmonary complications. Pulmonary function testing should not be routinely obtained, but is useful in patients with underlying lung disease where clinical evaluation is either insufficient or unable to determine their baseline lung function to determine optimization strategies. After a patient is identified as at risk for pulmonary complications, risk reduction strategies used include smoking cessation, respiratory physiotherapy, respiratory muscle training, and optimization of nutritional status. Intraoperative strategies include lung recruitment maneuvers, protective tidal volume of 6–9 mL/kg in noninjured lungs, positive end expiratory pressure of 10 cm H ₂ O to reduce atelectasis, and postoperative lung expansion techniques (see Ch. 45 , Systemic Complications: Respiratory).

Patients who currently smoke have a twofold increased risk for postoperative complications, with the highest risk in patients who have smoked within the past 2 months. Smoking abstinence can reduce the rate of such complications. Patients who have quit smoking for more than 6 months have a risk similar to those who do not smoke, and the beneficial effects of smoking cessation, including improvement in ciliary function and a decrease in sputum production, occur gradually over a period of several weeks. Physician counseling alone can aid in smoking cessation. Pharmacologic strategies to improve the quit rate for smoking include nicotine replacement therapy, bupropion, hypnosis therapy, and varenicline. Nicotine replacement therapy is available in several formulations, including transdermal patch, gum, nasal spray, inhaler, and lozenge. Bupropion is an atypical antidepressant, and varenicline is a partial agonist of the α4β2 nicotinic acetylcholine receptor. Second line agents are nortriptyline and clonidine which are not approved by the FDA for this purpose but can be effective as smoking cessation adjuncts. Brief counseling by physicians can aid in smoking cessation. A focused protocol to offer advice on smoking cessation, referral to telephone-based program (1-800-QUITNOW), and initial nicotine replacement and pharmacologic assistance has been developed by the Vascular Physicians Offer and Report (VAPOR) investigators.

For patients with a history of bronchospasm and chronic obstructive pulmonary disease, guidelines suggest the use of inhaled bronchodilators, β2 agonists, and anticholinergics as the mainstays of symptomatic therapy for patients with bronchial hyperreactivity. These interventions should begin at least 5 days before surgery. Systemic or inhaled corticosteroids have been recommended when the FEV1 is less than 80% of predicted in anticipation of general anesthesia. Chronic steroid dosing can be increased or decreased, and can be given intraoperatively depending on the underlying COPD severity and duration of surgery. In addition, instances of bronchospasm during intubation in patients with bronchial hyperreactivity not previously receiving bronchodilators are reduced with the use of albuterol and oral or inhaled steroids. The safety of perioperative corticosteroid use has been established, and it is not associated with death or serious infections. Lung expansion techniques, such as incentive spirometry, chest physical therapy, cough, postural drainage, ambulation, and continuous positive airway pressure, have been used to limit postoperative pulmonary complications, although no single modality is clearly superior, and there is little benefit to combining modalities. Despite the association of hypoalbuminemia with postoperative pulmonary complications, preoperative nutritional supplementation has not been shown to reduce incidence, however control of intra- and postoperative fluid resuscitation can.