Current Medical Diagnosis & Treatment 2015

3

Preoperative Evaluation & Perioperative Management

Hugo Q. Cheng, MD

EVALUATION OF THE ASYMPTOMATIC PATIENT

Patients without significant medical problems—especially those under age 50—are at very low risk for perioperative complications. Their preoperative evaluation should include a history and physical examination. Special emphasis is placed on obtaining a careful pharmacologic history and assessment of functional status, exercise tolerance, and cardiopulmonary symptoms and signs in an effort to reveal previously unrecognized disease that may require further evaluation prior to surgery. In addition, a directed bleeding history (Table 3–1) should be taken to uncover coagulopathy that could contribute to excessive surgical blood loss. Routine preoperative laboratory tests in asymptomatic healthy patients under age 50 have not been found to help predict or prevent complications. Even elderly patients undergoing minor or minimally invasive procedures (such as cataract surgery) are unlikely to benefit from preoperative screening tests.

Table 3–1. Findings suggestive of a bleeding disorder.

Chopra V et al. Perioperative practice: time to throttle back. Ann Intern Med. 2010 Jan 5;152(1):47–51. [PMID: 19949135]

Gupta A. Preoperative screening and risk assessment in the ambulatory surgery patient. Curr Opin Anaesthesiol. 2009 Dec;22(6):705–11. [PMID: 19633545]

Laine C et al. In the clinic. Preoperative evaluation. Ann Intern Med. 2009 Jul 7;151(1):ITC1–15. [PMID: 19581642]

CARDIAC RISK ASSESSMENT & REDUCTION IN NONCARDIAC SURGERY

Cardiac complications of noncardiac surgery are a major cause of perioperative morbidity and mortality. The most important perioperative cardiac complications are myocardial infarction (MI) and cardiac death. Other complications include heart failure (HF), arrhythmias, and unstable angina. The principal patient-specific risk factor is the presence of end-organ cardiovascular disease. This includes not only coronary artery disease and HF, but also cerebrovascular disease and chronic kidney disease if due to atherosclerosis. Diabetes mellitus, especially if treated with insulin, is considered a cardiovascular disease equivalent and has also been shown to increase the risk of cardiac complications. Major abdominal, thoracic, and vascular surgical procedures (especially abdominal aortic aneurysm repair) carry a higher risk of postoperative cardiac complications, likely due to their associated major fluid shifts, hemorrhage, and hypoxemia. These risk factors were identified in a validated multifactorial risk prediction tool: the Revised Cardiac Risk Index (RCRI) (Table 3–2). The RCRI is widely used for assessing and communicating cardiac risk and has been incorporated into perioperative management guidelines. Limited exercise capacity (eg, the inability to walk for two blocks at a normal pace or climb a flight of stairs without resting) also predicts higher cardiac risk. Emergency operations are also associated with greater cardiac risk. However, emergency operations should not be delayed by extensive cardiac evaluation. Instead, patients facing emergency surgery should be medically optimized for surgery as quickly as possible and closely monitored for cardiac complications during the perioperative period.

Table 3–2. Revised Cardiac Risk Index.

Another risk prediction tool, derived from the American College of Surgeons’ National Surgical Quality Improvement Program (NSQIP) patient database, identified five variables that predicted postoperative MI and cardiac arrest. These include patient age, the location or type of operation, serum creatinine > 1.5 g/dL (132.6 mcmol/L), dependency in activities of daily living, and the patient’s American Society of Anesthesiologists physical status classification. An online risk calculator using the NSQIP tool can be found at http://www.qxmd.com/calculate-online/cardiology/gupta-perioperative-cardiac-risk.

 Role of Preoperative Noninvasive Ischemia Testing

Most patients can be accurately risk-stratified by history and physical examination. A resting electrocardiogram (ECG) should also be obtained in patients with at least one RCRI predictor prior to major surgery. Additional noninvasive stress testing rarely improves risk stratification or management, especially in patients without RCRI predictors, in those who are undergoing minor operations, or those who have at least fair functional capacity. Patients with poor functional capacity or a high RCRI score are much more likely to suffer cardiac complications. Stress testing prior to vascular surgery in these patients can stratify them into low-risk and high-risk subgroups. The absence of ischemia on dipyridamole scintigraphy or dobutamine stress echocardiography is reassuring. In contrast, extensive inducible ischemia in this population predicts a very high risk of cardiac complications, which may not be modifiable by either medical management or coronary revascularization. The predictive value of an abnormal stress test result for nonvascular surgery patients is less well established. An approach to perioperative cardiac risk assessment and management in patients with known or suspected stable coronary artery disease is shown in Figure 3–1.

 Figure 3–1. Assessment and management of patients with known or suspected stable coronary artery disease (CAD) undergoing elective major noncardiac surgery. (OR, operating room.)

 Perioperative Management of Patients with Coronary Artery Disease

Patients with acute coronary syndromes require immediate management of their cardiac disease prior to any preoperative evaluation (see Chapter 10). In a large cohort study, postoperative MI typically occurred within 3 days of surgery, and was associated with a 30-day mortality rate of 11.6%. Postoperative MI is usually silent or may present without chest pain. Symptoms and signs that should prompt consideration of postoperative MI include unexplained hypotension, hypoxemia, or delirium. Screening asymptomatic patients for postoperative MI through the use of ECG or cardiac enzyme monitoring remains controversial, since it has not yet been demonstrated to improve outcomes.

  1. Medications

Preoperative antianginal medications, including beta-blockers, calcium channel blockers, and nitrates, should be continued throughout the perioperative period. Beta-adrenergic blocking drugs exert a cardioprotective effect in surgical patients. A small, randomized trial in vascular surgery patients with ischemia on dobutamine stress echocardiography found that bisoprolol reduced the 30-day risk of cardiac mortality or nonfatal MI from 34% to 3% in these high-risk patients. In contrast, subsequent larger trials found less benefit and potential harm in lower risk patients. In the largest of these studies, a high, fixed dose of metoprolol succinate given to patients with at least one RCRI predictor reduced the absolute risk of cardiac complications by 1.1%. However, this benefit was offset by a 0.8% absolute increase in total mortality, driven by greater incidence of stroke and death from sepsis. Because of the uncertain benefit-to-risk ratio of perioperative beta-blockade, it should be reserved for patients with a relatively high risk of cardiac complications. Suggested indications and starting doses for prophylactic beta-blockade are presented in Table 3–3. Ideally, beta-blockers should be started well in advance of surgery, to allow time to gradually titrate up the dose without causing excessive bradycardia or hypotension. The dose should be adjusted to maintain a heart rate between 50 and 70 beats per minute while keeping systolic blood pressure above 100 mm Hg. Beta-blockers should be continued for at least 3–7 days after surgery.

Table 3–3. Indications for prophylactic perioperative beta-blockade.1

A meta-analysis of randomized trials found that the use of HMG-CoA reductase inhibitors (statins) prevents MI in patients undergoing noncardiac surgery. Safety concerns, such as liver failure or rhabdomyolysis, have not materialized in these studies. Statins should be considered in all patients undergoing vascular surgery and other patients deemed to be at high risk for cardiac complications, regardless of lipid levels. Patients already taking statins should continue these agents during the perioperative period.

  1. Coronary Revascularization

Retrospective studies suggest that patients who had previously undergone coronary artery bypass grafting (CABG) surgery or percutaneous coronary interventions (PCI) have a relatively low risk of cardiac complications when undergoing subsequent noncardiac surgery. However, one trial randomized over 500 patients with angiographically proven coronary artery disease to either coronary revascularization (with either CABG or PCI) or medical management alone before vascular surgery. Postoperative nonfatal MI, 30-day mortality, and long-term mortality did not differ, suggesting that prophylactic revascularization before noncardiac surgery does not prevent cardiac complications. Thus, preoperative CABG or PCI should only be performed on patients who have indications for the procedure independent of the planned noncardiac operation. In addition, the perioperative cardiac mortality rate may be very high in patients who have undergone recent intracoronary stenting, if antiplatelet therapy is stopped prematurely. The presumed mechanism of this increased mortality is acute stent thrombosis. Therefore, elective surgery should be deferred for at least 4–6 weeks after placement of a bare-metal stent and for a full year after placement of a drug-eluting stent if antiplatelet therapy must be stopped perioperatively.

 Heart Failure & Left Ventricular Dysfunction

Decompensated HF, manifested by an elevated jugular venous pressure, an audible third heart sound, or evidence of pulmonary edema on physical examination or chest radiography, significantly increases the risk of perioperative cardiac complications. Elective surgery should be postponed in patients with decompensated HF until it can be evaluated and brought under control.

Patients with compensated left ventricular dysfunction are at increased risk for cardiac complications. In vascular surgery patients who had preoperative echocardiography, asymptomatic left ventricular dysfunction (either systolic or diastolic) was associated with a twofold increase in cardiac complications. In contrast, a history of symptomatic HF was associated with a sevenfold increase in risk. Current guidelines recommend preoperative echocardiography in patients without known HF with unexplained dyspnea and in patients with known HF with clinical deterioration. A small observational study found that routine echocardiography in patients with suspected heart disease or age ≥ 65 years old prior to emergency noncardiac surgery frequently led to a change in diagnosis or management plan. While this is not an established practice, preoperative echocardiography should be considered when there is uncertainty about the patient’s cardiac status.

Patients receiving diuretics and digoxin should have serum electrolyte and digoxin levels measured prior to surgery because abnormalities in these levels may increase the risk of perioperative arrhythmias. Clinicians must be cautious not to give too much diuretic, since the volume-depleted patient will be much more susceptible to intraoperative hypotension. The surgeon and anesthesiologist should be made aware of the presence and severity of left ventricular dysfunction so that appropriate decisions can be made regarding perioperative fluid management and intraoperative monitoring.

 Valvular Heart Disease

If the severity of valvular lesions is unknown, echocardiography should be performed prior to noncardiac surgery. Candidates for valve replacement surgery or valvuloplasty independent of the planned noncardiac surgery should have the valve correction procedure performed first. Patients with uncorrected severe or symptomatic aortic stenosis are at particular risk for cardiac complications. They should only undergo surgery after consultation with a cardiologist and anesthesiologist. In a series of patients with aortic stenosis who underwent noncardiac surgery, death or nonfatal MI occurred in 31% in patients with severe aortic stenosis (aortic valve area < 0.7 cm2), in 11% in those with moderate aortic stenosis (aortic valve area 0.7–1.0 cm2), and in 2% in those without aortic stenosis. Patients with asymptomatic aortic stenosis appeared to be at lower risk than patients with symptomatic aortic stenosis. Patients with mitral stenosis require heart rate control to prolong diastolic filling time. Regurgitant lesions are generally less problematic during surgery because the vasodilatory effect of anesthetics promotes forward flow. Patients with aortic regurgitation or aortic insufficiency likely benefit from afterload reduction and careful attention to volume status.

 Arrhythmias

The finding of a rhythm disturbance on preoperative evaluation should prompt consideration of further cardiac evaluation, particularly when the finding of structural heart disease would alter perioperative management. Patients with a rhythm disturbance without evidence of underlying heart disease are at low risk for perioperative cardiac complications. There is no evidence that the use of antiarrhythmic medications to suppress an asymptomatic arrhythmia alters perioperative risk.

Patients with symptomatic arrhythmias should not undergo elective surgery until their cardiac condition has been addressed. Thus, in patients with atrial fibrillation or other supraventricular arrhythmias, adequate rate control should be established prior to surgery. Symptomatic ventricular tachycardia must be thoroughly evaluated and controlled prior to surgery. Patients who have independent indications for a permanent pacemaker or implanted defibrillator should have it placed prior to noncardiac surgery. The anesthesiologist must be notified that a patient has an implanted pacemaker or defibrillator so that steps may be taken to prevent device malfunction caused by electromagnetic interference from the intraoperative use of electrocautery.

 Hypertension

Mild to moderate hypertension (systolic blood pressure below 180 mm Hg and diastolic blood pressure below 110 mm Hg) is associated with intraoperative blood pressure lability and asymptomatic myocardial ischemia but does not appear to be an independent risk factor for more serious cardiac complications. No evidence supports delaying surgery in order to better control mild to moderate hypertension. Most medications for chronic hypertension should generally be continued up to and including the day of surgery. Consideration should be given to holding angiotensin-converting enzyme inhibitors and angiotensin receptor blockers on the day of surgery in the absence of HF, since these agents may increase the risk of intraoperative hypotension. Diuretic agents, if not needed to control HF, are also frequently held on the day of surgery to prevent hypovolemia and electrolyte disorders.

Severe hypertension, defined as a systolic pressure > 180 mm Hg or diastolic pressure > 110 mm Hg, appears to be an independent predictor of perioperative cardiac complications, including MI and HF. It is reasonable to consider delaying surgery in patients with severe hypertension until blood pressure can be controlled, although it is not known whether the risk of cardiac complications is reduced with this approach.

Chopra V et al. Effect of perioperative statins on death, myocardial infarction, atrial fibrillation, and length of stay: a systematic review and meta-analysis. Arch Surg. 2012 Feb;147(2):181–9. [PMID: 22351917]

Devereaux PJ et al. Characteristics and short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: a cohort study. Ann Intern Med. 2011 Apr 19;154(8):523–8. [PMID: 21502650]

Gupta PK et al. Development and validation of a risk calculator for prediction of cardiac risk after surgery. Circulation. 2011 Jul 26;124(4):381–7. [PMID: 21730309]

Task Force for Preoperative Cardiac Risk Assessment and Perioperative Cardiac Management in Non-cardiac Surgery; European Society of Cardiology (ESC) et al. Guidelines for pre-operative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery. Eur Heart J. 2009 Nov;30(22):2769–812. [PMID: 19713421]

PULMONARY EVALUATION IN NON–LUNG RESECTION SURGERY

Pneumonia and respiratory failure requiring prolonged mechanical ventilation are the most important postoperative pulmonary complications. The occurrence of these complications has been associated with a significant increase in mortality and hospital length of stay. Pulmonary thromboembolism is another serious complication; prophylaxis against venous thromboembolic disease is described in Chapter 14.

 Risk Factors for the Development of Postoperative Pulmonary Complications

The risk of developing a pulmonary complication is highest in patients undergoing cardiac, thoracic, and upper abdominal surgery, with reported complication rates ranging from 9% to 19%. The risk in patients undergoing lower abdominal or pelvic procedures ranges from 2% to 5%, and for extremity procedures the range is < 1–3%. The pulmonary complication rate for laparoscopic procedures appears to be much lower than that for open procedures. In one series of over 1500 patients who underwent laparoscopic cholecystectomy, the pulmonary complication rate was < 1%. Other procedure-related risk factors include prolonged anesthesia time, need for general anesthesia, and emergency operations.

Among the many patient-specific risk factors for postoperative pulmonary complications, the strongest predictor appears to be advanced age. Surgical patients in their seventh decade had a fourfold higher risk of pulmonary complications compared with patients under age 50. The presence and severity of systemic disease of any type is associated with pulmonary complications. In particular, patients with chronic obstructive pulmonary disease (COPD) or HF have at least twice the risk compared with patients without these conditions. A risk calculator for assessing the risk of postoperative respiratory failure was derived from the NSQIP patient database (http://www.qxmd.com/calculate-online/respirology/postoperative-respiratory-failure-risk-calculator). Predictors in this model include the type of surgery, emergency surgery, preoperative sepsis, dependency in activities of daily living, and the patient’s American Society of Anesthesiologists physical status classification.

Patients with well-controlled asthma at the time of surgery are not at increased risk for pulmonary complications. Obesity causes restrictive pulmonary physiology, which may increase pulmonary risk in surgical patients. However, it is unclear if obesity is an independent risk predictor. Obstructive sleep apnea has been associated with a variety of postoperative complications, particularly in patients undergoing bariatric surgery. The STOP screening questionnaire asks whether a patient has snoring, tiredness during the day, observed apnea, and high blood pressure. The presence of two or more of these findings had a 78% positive predictive value for obstructive sleep apnea and was associated with a doubled risk for postoperative pulmonary complications. A summary of risk factors for pulmonary complications is presented in Table 3–4.

Table 3–4. Clinical risk factors for postoperative pulmonary complications.

Upper abdominal or cardiothoracic surgery

Prolonged anesthesia time (> 4 hours)

Emergency surgery

Age > 60 years

Chronic obstructive pulmonary disease

Heart failure

Severe systemic disease

Tobacco use (> 20 pack-years)

Impaired cognition or sensorium

Functional dependency or prior stroke

Preoperative sepsis

Low serum albumin level

Obstructive sleep apnea

 Pulmonary Function Testing& Laboratory Studies

Few data support the use of preoperative testing to assess pulmonary risk. The main role for preoperative pulmonary function testing (PFT) is to help identify and characterize pulmonary disease in patients with unexplained symptoms prior to major abdominal or cardiothoracic surgery. In patients with diagnosed lung disease, PFT often adds little information above clinical assessment. Furthermore, there is no clear degree of PFT abnormality that can be used as an absolute contraindication to non–lung resection surgery. Chest radiographs in unselected patients also rarely add clinically useful information. In one study, only 0.1% of routine preoperative chest radiographs changed clinical management. They may be more useful in patients who are undergoing abdominal or thoracic surgery who are over age 50 or have known cardiopulmonary disease. Some experts have also advocated polysomnography to diagnose obstructive sleep apnea prior to bariatric surgery, but the benefits of this approach are unproven. Abnormally low or high blood urea nitrogen levels (indicating malnutrition or kidney disease, respectively) and hypoalbuminemia predict higher risk of pulmonary complications and mortality, although the added value of laboratory testing over clinical assessment is uncertain. Arterial blood gas measurement is not routinely recommended except in patients with known lung disease and suspected hypoxemia or hypercapnia.

 Perioperative Management

Retrospective studies have shown that smoking cessation reduced the incidence of pulmonary complications, but only if it was initiated at least 1–2 months before surgery. A meta-analysis of randomized trials found that preoperative smoking cessation programs reduced both pulmonary and surgical wound complications, especially if smoking cessation was initiated at least 4 weeks prior to surgery. The preoperative period may be an optimal time to initiate smoking cessation efforts. A systematic review found that smoking cessation programs started in a preoperative evaluation clinic increased the odds of abstinence at 3–6 months by nearly 60%.

The incidence of postoperative pulmonary complications in patients with COPD or asthma may be reduced by preoperative optimization of pulmonary function. Patients who are wheezing should receive preoperative therapy with bronchodilators and, in certain cases, corticosteroids. Antibiotics may be beneficial for patients with COPD who cough with purulent sputum. Patients receiving oral theophylline should continue taking the drug perioperatively. A serum theophylline level should be measured to rule out toxicity.

Postoperative risk reduction strategies have centered on promoting lung expansion through the use of incentive spirometry, continuous positive airway pressure (CPAP), intermittent positive-pressure breathing (IPPB), and deep breathing exercises. Although trial results have been mixed, all these techniques have been shown to reduce the incidence of postoperative atelectasis and, in a few studies, to reduce the incidence of postoperative pulmonary complications. In most comparative trials, these methods were equally effective. Given the higher cost of CPAP and IPPB, incentive spirometry and deep breathing exercises are the preferred methods for most patients. Incentive spirometry must be performed for 15 minutes every 2 hours. Deep breathing exercises must be performed hourly and consist of 3-second breath-holding, pursed lip breathing, and coughing. These measures should be started preoperatively and be continued for 1–2 days postoperatively.

Johnson DC et al. Perioperative pulmonary complications. Curr Opin Crit Care. 2011 Aug;17(4):362–9. [PMID: 21734490]

Mills E et al. Smoking cessation reduces postoperative complications: a systematic review and meta-analysis. Am J Med. 2011 Feb;124(2):144–54. [PMID: 21295194]

Qaseem A et al; Clinical Efficacy Assessment Subcommittee of the American College of Physicians. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: a guideline from the American College of Physicians. Ann Intern Med. 2006 Apr 18;144(8):575–80. [PMID: 16618955]

EVALUATION OF THE PATIENT WITH LIVER DISEASE

Patients with serious liver disease are at increased risk for perioperative morbidity and demise. Appropriate preoperative evaluation requires consideration of the effects of anesthesia and surgery on postoperative liver function and of the complications associated with anesthesia and surgery in patients with preexisting liver disease.

 The Effects of Anesthesia & Surgery on Liver Function

Postoperative elevation of serum aminotransferase levels is a relatively common finding after major surgery. Most of these elevations are transient and not associated with hepatic dysfunction. While direct hepatotoxicity is rare with modern anesthetics agents, these drugs may cause deterioration of hepatic function via intraoperative reduction in hepatic blood flow leading to ischemic injury. Medications used for regional anesthesia produce similar reductions in hepatic blood flow and thus may be equally likely to lead to ischemic liver injury. Intraoperative hypotension, hemorrhage, and hypoxemia may also contribute to liver injury.

 Risk Assessment in Surgical Patientswith Liver Disease

Screening unselected patients with liver function tests has a low yield and is not recommended. Patients with suspected or known liver disease based on history or physical examination, however, should have measurement of liver enzyme levels as well as tests of hepatic synthetic function performed prior to surgery.

Acute hepatitis increases surgical mortality risk. In three small series of patients with acute viral hepatitis who underwent abdominal surgery, the mortality rate was roughly 10%. Similarly, patients with undiagnosed alcoholic hepatitis had high mortality rates when undergoing abdominal surgery. Thus, elective surgery in patients with acute viral or alcoholic hepatitis should be delayed until the acute episode has resolved. In the absence of cirrhosis or synthetic dysfunction, chronic viral hepatitis is unlikely to increase risk significantly. A large cohort study of hepatitis C seropositive patients who underwent surgery found a mortality rate of less than 1%. Similarly, nonalcoholic fatty liver disease by itself probably does not pose a serious risk in surgical patients.

In patients with cirrhosis, postoperative complication rates correlate with the severity of liver dysfunction. Traditionally, severity of dysfunction has been assessed with the Child-Turcotte-Pugh score (seeChapter 16). Patients with Child-Turcotte-Pugh class C cirrhosis who underwent portosystemic shunt surgery, biliary surgery, or trauma surgery during the 1970s and 1980s had a 50–85% mortality rate. Patients with Child-Turcotte-Pugh class A or B cirrhosis who underwent abdominal surgery during the 1990s, however, had relatively low mortality rates (hepatectomy 0–8%, open cholecystectomy 0–1%, laparoscopic cholecystectomy 0–1%). A conservative approach would be to avoid elective surgery in patients with Child-Turcotte-Pugh class C cirrhosis and pursue it with great caution in class B patients. The Model for End-stage Liver Disease (MELD) score, based on bilirubin and creatinine levels, and the prothrombin time expressed as the International Normalized Ratio, also predicted surgical mortality and outperformed the Child-Turcotte-Pugh classification in some studies. A web-based risk assessment calculator incorporating age and MELD score can predict both perioperative and long-term mortality (mayoclinic.org/meld/mayomodel9.html).

In addition, when surgery is elective, it is prudent to attempt to reduce the severity of ascites, encephalopathy, and coagulopathy preoperatively. Ascites is a particular problem in abdominal operations, where it can lead to wound dehiscence or hernias. Great care should be taken when using analgesics and sedatives, as this can worsen hepatic encephalopathy. In general, short-acting agents and lower doses should be used. Patients with coagulopathy should receive vitamin K (if there is concern for concomitant malnutrition) and may need fresh frozen plasma transfusion at the time of surgery.

O’Leary JG et al. Surgery in the patient with liver disease. Clin Liver Dis. 2009 May;13(2):211–31. [PMID: 19442915]

PREOPERATIVE HEMATOLOGIC EVALUATION

Three of the more common clinical situations faced by the medical consultant are the patient with anemia, the assessment of bleeding risk, and the perioperative management of oral anticoagulation.

Preoperative anemia is common, with a prevalence of 43% in a large cohort of elderly veterans undergoing surgery. The main goals of the preoperative evaluation of the anemic patient are to determine the need for preoperative diagnostic evaluation and the need for transfusion. When feasible, the diagnostic evaluation of the patient with previously unrecognized anemia should be done prior to surgery because certain types of anemia (particularly that due to sickle cell disease, hemolysis, and acute blood loss) have implications for perioperative management. These types of anemia are typically associated with an elevated reticulocyte count. While preoperative anemia is associated with higher perioperative morbidity and mortality, it is not known whether correction of preoperative anemia with transfusions or erythropoiesis stimulating agents will improve postoperative outcomes. Determination of the need for preoperative transfusion in an individual patient must consider factors other than the absolute hemoglobin level, including the presence of cardiopulmonary disease, the type of surgery, and the likely severity of surgical blood loss. The few studies that have compared different postoperative transfusion thresholds failed to demonstrate improved outcomes with a more aggressive transfusion strategy. One trial randomized hip fracture patients, most of whom with cardiovascular disease, to either transfusion to maintain a hemoglobin level > 10 g/dL (100 g/L) or transfusion for symptomatic anemia. Patients receiving symptom-triggered transfusion received far few units of packed red blood cells without increased mortality or complication rates.

The most important component of the bleeding risk assessment is a directed bleeding history (see Table 3–1). Patients who are reliable historians and who reveal no suggestion of abnormal bleeding on directed bleeding history and physical examination are at very low risk for having an occult bleeding disorder. Laboratory tests of hemostatic parameters in these patients are generally not needed. When the directed bleeding history is unreliable or incomplete or when abnormal bleeding is suggested, a formal evaluation of hemostasis should be done prior to surgery and should include measurement of the prothrombin time, activated partial thromboplastin time, and platelet count (see Chapter 13).

Patients receiving long-term oral anticoagulation are at risk for thromboembolic complications when an operation requires interruption of this therapy. A recent meta-analysis of cohort studies found that approximately 1% of patients who had interruption of anticoagulation for a procedure suffered a thrombotic complication. “Bridging” anticoagulation, where unfractionated or low-molecular-weight heparin is administered parenterally while oral anticoagulants are held, is commonly practiced but its benefits are uncertain. In the same meta-analysis, there was no reduction in thrombotic risk with bridging anticoagulation. In addition, the patients who received bridging anticoagulation had a 3.7% incidence of serious bleeding, compared with 0.9% for patients who did not receive bridging anticoagulation. Most experts recommend bridging therapy only in patients at high risk for thromboembolism. An approach to perioperative anticoagulation management is shown in Table 3–5, but the recommendations must be considered in the context of patient preference and hemorrhagic risk. Oral direct thrombin inhibitors should be withheld several days prior to surgery, based on the patient’s renal function (Table 3–6). There is no antidote to reverse the anticoagulant effect of these medications, so they should only be restarted after surgery when adequate hemostasis is assured.

Table 3–5. Recommendations for perioperative anticoagulation management.

Table 3–6. Recommendations for preoperative management of oral direct thrombin inhibitors.1

Douketis JD et al. Perioperative management of antithrombotic therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012 Feb;141 (2 Suppl):e326S–50S. Erratum in: Chest. 2012 Apr;141(4):1129 [PMID: 22315266]

Mussalam KM et al. Preoperative anaemia and postoperative outcomes in non-cardiac surgery: a retrospective cohort study. Lancet. 2011 Oct 15;378(9800):1396–407. [PMID: 21982521]

Siegal D et al. Periprocedural heparin bridging in patients receiving vitamin K antagonists: systematic review and meta-analysis of bleeding and thromboembolic rates. Circulation. 2012 Sept 25;126(13):1630–9. [PMID: 22912386]

NEUROLOGIC EVALUATION

Delirium can occur after any major operation but is particularly common after hip fracture repair and cardiovascular surgery, where the incidence is 30–60%. Postoperative delirium has been associated with higher rates of major postoperative cardiac and pulmonary complications, poor functional recovery, an increased length of hospital stay, an increased risk of subsequent dementia and functional decline, and increased mortality. Several preoperative and postoperative factors have been associated with the development of postoperative delirium, most notably age, preoperative functional or cognitive impairment, preoperative psychotropic drug use, and derangements of serum chemistry. Patients with multiple risk factors are at especially high risk. Delirium occurred in half of the patients with at least three of the risk factors listed in Table 3–7.

Table 3–7. Risk factors for the development of postoperative delirium.

Two types of interventions to prevent delirium have been evaluated: focused geriatric care and psychotropic medications. In a randomized, controlled trial of hip fracture surgery patients, those who received daily visits and targeted recommendations from a geriatrician had a lower risk of postoperative delirium (32%) than the control patients (50%). Common interventions to prevent delirium were maintenance of the hematocrit > 30%; minimizing the use of benzodiazepines and anticholinergic medications; maintenance of regular bowel function; and early discontinuation of urinary catheters. Other studies comparing postoperative care in specialized geriatrics units with standard wards have shown similar reductions in the incidence of delirium. Limited data support the effectiveness of using low doses of neuroleptics to prevent postoperative delirium, but this practice is uncommon. While clinically apparent delirium usually resolves over several days, some patients will suffer from subtler postoperative cognitive dysfunction that can last for weeks or months after surgery. Patients who experienced postoperative delirium are more likely to have subsequent postoperative cognitive dysfunction.

Stroke complicates < 1% of all surgical procedures but may occur in 1–6% of patients undergoing cardiac or carotid artery surgery. Most of the strokes in cardiac surgery patients are embolic in origin, and about half occur within the first postoperative day. Stroke after cardiac surgery is associated with significantly increased mortality, up to 22% in some studies. A prediction model for stroke after CABG surgery includes the following risk factors: age > 60 years, female sex, urgent or emergency surgery, diabetes mellitus, chronic kidney disease, peripheral vascular disease, and systolic dysfunction.

Symptomatic carotid artery stenosis is associated with a high risk of stroke in patients undergoing cardiac surgery. In general, symptomatic carotid lesions should be treated prior to elective cardiac surgery. In contrast, most studies suggest that asymptomatic carotid bruits and asymptomatic carotid stenosis are associated with little or no increased risk of stroke in surgical patients. Prophylactic carotid endarterectomy or stenting in patients with asymptomatic carotid artery disease is unlikely to be beneficial in most patients, as the stroke risk of the carotid procedure likely outweighs any risk reduction it provides in a subsequent operation. On the other hand, patients with independent indications for such procedures (see Chapter 12) should probably have the carotid operation prior to the elective surgery. A meta-analysis of trials comparing carotid endarterectomy to carotid stenting found that endarterectomy led to fewer periprocedural strokes.

Bateman BT et al. Perioperative acute ischemic stroke in noncardiac and nonvascular surgery: incidence, risk factors, and outcomes. Anesthesiology. 2009 Feb;110(2):231–8. [PMID: 19194149]

Robinson TN et al. Preoperative cognitive dysfunction is related to adverse postoperative outcomes in the elderly. J Am Coll Surg. 2012 Jul;215(1):12–8. [PMID: 22626912]

Saczynski JS et al. Cognitive trajectories after postoperative delirium. N Engl J Med. 2012 Jul 5;367(1):30–9. [PMID: 22762316]

MANAGEMENT OF ENDOCRINE DISEASES

 Diabetes Mellitus

Patients with diabetes mellitus are at increased risk for postoperative infections, particularly those involving the surgical site. Patients with a preoperative hemoglobin A1c< 7% have roughly half the risk for developing a postoperative infection compared with those with a hemoglobin A1c > 7%. Even in patients without diabetes, hyperglycemia is associated with surgical site infection although proof of a causal relationship is lacking. The most challenging issue in diabetic patients, however, is the maintenance of glucose control during the perioperative period. The increased secretion of cortisol, epinephrine, glucagon, and growth hormone during surgery is associated with insulin resistance and hyperglycemia in diabetic patients. The goal of management is the prevention of severe hyperglycemia or hypoglycemia in the perioperative period.

The ideal postoperative blood glucose level is not known. Trials have demonstrated that tighter perioperative glycemic control leads to better clinical outcomes in cardiac surgery patients in a critical care unit. This finding is not generally applicable to other surgical patients, however, as a subsequent trial demonstrated increased mortality with tight control in surgical patients in an intensive care unit. Data are lacking on risks and benefits of tight control in patients outside of intensive care units. The American College of Physicians recommends maintaining serum glucose between 140 mg/dL and 200 mg/dL (7.8–11.1 mmol/L), whereas the British National Health Service guidelines recommend a range of 108–180 mg/dL (6–10 mmol/L).

The specific pharmacologic management of diabetes during the perioperative period depends on the type of diabetes (insulin-dependent or not), the level of glycemic control, and the type and length of surgery. In general, all patients with type 1 diabetes and some with type 2 diabetes will need an intravenous insulin infusion perioperatively. Perioperative management of all diabetic patients requires frequent blood glucose monitoring to prevent hypoglycemia and to ensure prompt treatment of hyperglycemia. Recommendations for glycemic control in patients who generally do not need intraoperative insulin are shown in Table 3–8. Perioperative use of corticosteroids, common in neurosurgical and organ transplant procedures, increases glucose intolerance. Patients receiving corticosteroids often require additional regular insulin with meals, while their fasting glucose levels may remain relatively unchanged.

Table 3–8. Perioperative management of diabetic patients who do not need insulin.

 Corticosteroid Replacement

Perioperative complications (predominantly hypotension) resulting from primary or secondary adrenocortical insufficiency are rare. The common practice of administering high-dose corticosteroids during the perioperative period in patients at risk for adrenocortical insufficiency has not been rigorously studied. While definitive recommendations regarding perioperative corticosteroid therapy cannot be made, a conservative approach would be to consider any patient who has received the equivalent of at least 7.5 mg of prednisone daily for 3 weeks within the past year to be at risk for having adrenocortical insufficiency. Patients who have been taking less than 5 mg of prednisone daily and those receiving alternate day corticosteroid dosing are unlikely to require supplemental coverage. A commonly used regimen is 100 mg of hydrocortisone given intravenously daily, divided every 8 hours, beginning before induction of anesthesia and continuing for 24–48 hours. Tapering the dose is not necessary. Patients receiving long-term maintenance corticosteroid therapy should also continue their usual dose throughout the perioperative period.

 Thyroid Disease

Severe symptomatic hypothyroidism has been associated with perioperative complications, including intraoperative hypotension, HF, cardiac arrest, and death. Elective surgery should be delayed in patients with severe hypothyroidism until adequate thyroid hormone replacement can be achieved. Similarly, patients with symptomatic hyperthyroidism are at risk for perioperative thyroid storm and should not undergo elective surgery until their thyrotoxicosis is controlled. An endocrinologist should be consulted if emergency surgery is needed in such patients. Conversely, patients with asymptomatic or mild hypothyroidism generally tolerate surgery well, with only a slight increase in the incidence of intraoperative hypotension; surgery need not be delayed for the month or more required to ensure adequate thyroid hormone replacement.

Dhatariya K et al; Joint British Diabetes Societies. NHS Diabetes guideline for the perioperative management of the adult patient with diabetes. Diabet Med. 2012 Apr;29(4):420–33. [PMID: 22288687]

Qaseem A et al. Use of intensive insulin therapy for the management of glycemic control in hospitalized patients: a clinical practice guideline from the American College of Physicians. Ann Intern Med. 2011 Feb 15;154(4):260–7. [PMID: 21320941]

Richards JE et al. Relationship of hyperglycemia and surgical-site infection in orthopaedic surgery. J Bone Joint Surg Am. 2012 Jul 3;94(13):1181–6. [PMID: 22760385]

KIDNEY DISEASE

Approximately 1% of patients suffer a significant reduction in kidney function after major surgery. The risk is much higher, however, in patients undergoing cardiac operations, where 10–30% of patients develop acute kidney injury. The development of acute kidney injury is an independent predictor of mortality, even if renal dysfunction resolves. The mortality associated with the development of perioperative acute kidney injury that requires dialysis exceeds 50%. Risk factors associated with postoperative deterioration in kidney function are shown in Table 3–9. Several medications, including “renal dose” dopamine, mannitol, N-acetylcysteine, and furosemide, have been evaluated in an attempt to preserve kidney function during the perioperative period. None of these have proved effective in clinical trials and generally should not be used for this indication. Maintenance of adequate intravascular volume is likely to be the most effective method to reduce the risk of perioperative deterioration in kidney function. Exposure to renal toxic agents such as nonsteroidal anti-inflammatory drugs and intravenous contrast should be minimized or avoided. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers reduce renal perfusion and may increase the risk of perioperative acute kidney injury. Although firm evidence is lacking, it may be useful to temporarily discontinue these medications in patients at risk for perioperative acute kidney injury.

Table 3–9. Risk factors for the development of postoperative acute kidney failure.

Preoperative chronic kidney disease

Aortic and major peripheral vascular surgery

Cardiac surgery

Severe heart failure

Preoperative jaundice

Age > 70 years

Diabetes mellitus

COPD requiring daily bronchodilator therapy

COPD, chronic obstructive pulmonary disease.

Although the mortality rate for elective major surgery is low (1–4%) in patients with dialysis-dependent chronic kidney disease, the risk for perioperative complications, including postoperative hyperkalemia, pneumonia, fluid overload, and bleeding, is substantially increased. Postoperative hyperkalemia requiring emergent hemodialysis has been reported to occur in 20–30% of patients. Patients should undergo dialysis preoperatively within 24 hours before surgery, and their serum electrolyte levels should be measured just prior to surgery and monitored closely during the postoperative period.

Borthwick E et al. Perioperative acute kidney injury: risk factors, recognition, management, and outcomes. BMJ. 2010 Jul 5;341: c3365. [PMID: 20603317]

ANTIBIOTIC PROPHYLAXIS OF SURGICAL SITE INFECTIONS

There are an estimated 0.5–1 million surgical site infections annually in the United States. Surgical site infection is estimated to occur in roughly 4% of general or vascular operations. For most major procedures, the use of prophylactic antibiotics has been demonstrated to reduce the incidence of surgical site infections significantly. For example, antibiotic prophylaxis in colorectal surgery reduces the incidence of surgical site infection from 25–50% to below 20%. In addition, in a case-control study of Medicare beneficiaries, the use of preoperative antibiotics within 2 hours of surgery was associated with a twofold reduction in 60-day mortality.

Multiple studies have evaluated the effectiveness of different antibiotic regimens for various surgical procedures. In most cases, no single antibiotic regimen has been shown to be superior. Several general conclusions can be drawn from these data. First, substantial evidence suggests that a single dose of an appropriate intravenous antibiotic—or combination of antibiotics—is as effective as multiple-dose regimens that extend into the postoperative period. For longer procedures, the dose should be repeated every 3–4 hours to ensure maintenance of a therapeutic serum level. In colorectal surgery, however, three doses of an intravenous cephalosporin have been shown to reduce surgical site infection incidence compared with a single dose. Similarly, at least 24 hours of postoperative antibiotic therapy is recommended after cardiac surgery. Second, for most procedures, a first-generation cephalosporin is as effective as later-generation agents. However, in a large randomized trial of colorectal surgery patients, the use of prophylactic ertapenem significantly reduced the surgical site infection rate compared to that for cefotetan. Third, prophylactic antibiotics should be given intravenously at induction of anesthesia or roughly 30–60 minutes prior to the skin incision. Although the type of procedure is the main factor determining the risk of developing a surgical site infection, certain patient factors have been associated with increased risk, including diabetes mellitus, older age, obesity, heavy alcohol consumption, admission from a long-term care facility, and multiple medical comorbidities.

Other strategies to prevent surgical site infections have proven to be controversial. Evidence suggests that nasal carriage with Staphylococcus aureus is associated with a twofold to ninefold increased risk of surgical site and catheter-related infections in surgical patients. Treatment of nasal carriers of S aureus with 2% mupirocin ointment (twice daily intranasally for 3 days) prior to cardiac surgery decreases the risk of surgical site infections. However, in a 2008 cohort study, universal screening for methicillin-resistant S aureus in surgical patients failed to reduce infection rates from this pathogen. High concentration oxygen delivered in the immediate postoperative period may reduce surgical site infections in patients undergoing colorectal surgery or operations requiring general anesthesia. Preoperative bathing with antiseptic agents and preoperative hair removal are common practices but have not demonstrated a reduction in surgical site infections in randomized trials. The use of razors for hair removal actually seems to increase the risk of surgical site infections and is therefore specifically not recommended. If preoperative hair removal is indicated, the use of clippers is preferred.

Guidelines for antibiotic prophylaxis against infective endocarditis in patients undergoing invasive procedures are presented in Chapter 33. The American Association of Orthopaedic Surgeons recommends consideration of prophylactic antibiotics in patients with prosthetic joints on a case-by-case basis. More definitive or evidence-based guidelines for antibiotic prophylaxis against prosthetic joint infection are lacking.

Enzler MJ et al. Antimicrobial prophylaxis in adults. Mayo Clin Proc. 2011 Jul;86(7):686–701. [PMID: 21719623]

Suzuki T et al. Optimal duration of prophylactic antibiotic administration for elective colon cancer surgery: a randomized, clinical trial. Surgery. 2011 Feb;149(2):171–8. [PMID: 20655559]