Preoperative Evaluation

The most common symptoms of heart disease are dyspnea, fatigue, chest pain, and palpitation. It is important to inquire about exercise tolerance, paroxysmal nocturnal dyspnea, orthopnea, peripheral edema, irregular heartbeat, and chest pain. One should be aware of significant past illnesses such as congenital heart disease, rheumatic fever, MI, atherosclerotic vascular disease, diabetes mellitus, hypertension, and autoimmune disease. Also, use of cardiac pacemakers, previous cardiac surgery, and past or present use of diuretics, digitalis, coronary vasodilators, antihypertensive drugs, and antiarrhythmic drugs should be noted. A history of angina pectoris, MI, stroke, cerebral ischemic attacks, intermittent claudication, or previous treatment for heart disease or hypertension should alert the surgeon to the possibility of a cardiac abnormality requiring further evaluation.

Additionally, recent MI, congestive heart failure (CHF) and myocardial ischemia have all been shown to increase the risk of perioperative morbidity and mortality, namely postoperative myocardial infarction. Conditions contraindicating elective surgery because of increased risk are acute MI, recent or crescendo angina pectoris, aortic stenosis, jugular congestion, and atrioventricular block.

Preoperative Preparation

The cardiac status of a patient undergoing spine surgery should be optimized prior to elective procedures. Special attention should be paid to correction of electrolyte imbalance, fluid excess, and anemia. It is important to avoid hypotension, hypoxia, fluid overload, and insufficiently treated pain. Cardiac safety of aspirin discontinuation should be carefully evaluated.

Cardiac contraindications to elective surgical procedures include unstable angina, decompensated congestive heart failure (NYHA class IV), intractable cardiac arrhythmias and conduction defects, and severe valvular disease. Preoperative evaluation is directed toward detecting and treating these conditions.

Treatable causes of CHF include myocardial ischemia and its sequelae, valvular disease, bacterial endocarditis, sepsis, arrhythmias, hyperthyroidism, and hypertension. Careful perioperative management of these conditions will certainly decrease morbidity. Anginal chest pain may reflect severe coronary artery disease. Symptoms and signs denoting severe angina include associated sweating and nausea, poor response to coronary vasodilators (nitroglycerin), no relief with rest, frequent attacks, prolonged pain, and ECG evidence of ischemia.

High-risk coronary artery lesions include left main coronary artery occlusion, high left anterior descending artery lesions, and lesions in multiple vessels. Elective procedures should be postponed in patients with such lesions. Patients who need urgent or emergent procedures require intensive perioperative management.

In hypertensive patients the blood pressure should be normalized before surgery. There is a linear correlation between preoperative blood pressure and postoperative myocardial ischemia.

Postoperative Management

Cardiac complications affect 2% of patients undergoing surgery worldwide every year. Close monitoring and management postoperatively can help prevent adverse events.

Patients who are undergoing beta blockade in the preoperative period should continue with therapy postoperatively. Studies reviewing patients undergoing noncardiac vascular surgery reveal that patients with chronic beta blockade therapy withdrawn in the postoperative period have a 50% rate of perioperative MI and 38% mortality within 1 year of surgery. However, patients should not have beta blockade initiated just prior to surgery, as therapy for less than 1 month has been linked to decreased MI but increased mortality, stroke, and hypotension by the POISE (perioperative ischemic evaluation) trial. Similarly, in a retrospective cohort study of nearly 50,000 patients, Wijeysundera and associates found patients with beta blockade initiated 1 to 7 days experienced increased 30-day mortality compared with patients undergoing beta blockade for greater than 1 month preoperatively. No difference was seen between patients treated for 8 to 30 days versus greater than 31.

Postoperative Cardiac Complications

Most postoperative MIs occur on the second or third postoperative day, and hence serial ECGs for 3 days may be considered in patients with known coronary artery disease. Chest pain is often difficult to evaluate in the postoperative period, with studies showing 65% of patients with perioperative MI are entirely asymptomatic. MI may become apparent only because of hypotension or arrhythmia. Serial cardiac isoenzyme studies and ECG are especially useful for identifying postoperative ischemia and should be obtained if patients are known to be at high risk or if concerning signs and symptoms arise. Postoperative troponin elevation, even in the absence of defining features of MI, has been associated with significant increase risk of mortality. Cardiac injury may additionally make patients more susceptible to noncardiac complications such as pneumonia. Postoperative treatment for MI entails vigorous support and monitoring. Arrhythmias and cardiac failure should be treated as they arise.

In the presence of bradycardia, one should look for anesthetic or medication excess, hypoxia, atrioventricular block, or vagal stimulation by visceral traction, carotid sinus compression, or traction on extraocular muscles. If hypotension occurs, one should again look for anesthetic excess, myocardial ischemia, or inadequate preload caused by blood or fluid losses, obstruction of venous return, or vasodilation. Treatment should include identification of the underlying cause, and immediate correction of the abnormality should be pursued.

Treatment of the major arrhythmias is a complex problem requiring close collaboration of the internist and surgeon. If the surgeon is required to provide emergency treatment until the internist arrives, a general knowledge of cardiac arrhythmias and their treatment is important. Diagnosis of the arrhythmia is made from the ECG. Atrial fibrillation decreases cardiac efficiency and may cause congestive failure if rapid ventricular response is left untreated. Treatment involves slowing the rate by adequate digitalization, calcium channel blockade in patients with no history of heart failure or cardiomyopathy, or beta blockade. Intravenous beta-blockers such as metoprolol can be dosed several times in a short period in hopes of controlling the rate; if this is ineffective, patients may require transfer to intensive care for continuous infusions. Conversion to normal sinus rhythm by quinidine or direct current (DC) countershock may be an option if onset of atrial fibrillation is known to be recent.

Preoperative Evaluation

The most common symptoms of pulmonary disease are dyspnea at rest or after minor exertion, cough, sputum production, wheezing, chest pain, and hemoptysis. It is important to document any history of tuberculosis, recent upper respiratory infection, chronic pulmonary disease, or asthma. One must determine the degree of tobacco and alcohol use as well as previous occupational exposures to coal dust, asbestos, and silica dusts. Establishment of a medication history, particularly regarding the use of corticosteroids, is especially important.

Pulmonary risk is minimally affected by age, with other factors taking a much more important role. Obesity may cause restrictive lung disease, decreasing thoracic compliance and increasing atelectasis; body mass index greater than 30 were found to be more likely to experience pulmonary complications than patients of normal weight. Smoking is a significant risk for pulmonary complication, with some improvement seen if patients succeed in smoking cessation for greater than 2 months preoperatively. If patients are able to quit smoking for 6 months prior to surgery, complication rates approach those of nonsmokers. Chronic obstructive pulmonary disease (COPD) increases postoperative complication rates sixfold, requiring disease optimization prior to surgery.

Pulmonary risk is also affected by the type of surgery planned, with the surgical site being the most important predictor of complications. Surgeries requiring a thoracic approach carry a 15% to 20% risk of major pulmonary complication such as atelectasis, pneumonia, and respiratory failure, which lead to higher postoperative mortality rates. Additionally, duration of anesthesia plays an important role, with increased rates of complications seen when surgery lasts longer than 3.5 hours.

Preoperative Preparation

Patients without pulmonary symptoms can be expected to tolerate surgery from a respiratory standpoint. If a patient can climb two flights of stairs without shortness of breath, further evaluation of respiratory status is generally unnecessary. Factors that can predispose a patient to postoperative pulmonary complications are long-term cigarette smoking, chronic obstructive pulmonary disease, upper abdominal and thoracic procedures, acute respiratory infections, and restrictive disorders such as obesity, pulmonary fibrosis, and neuromuscular and skeletal disease. Patients with one or more of these factors require careful preoperative preparation, and most should undergo complete pulmonary evaluation. Elective procedures should be postponed until maximum pulmonary function has been achieved. Patients should stop smoking well before surgery; though the ideal timing is uncertain, 2 months of cessation has been shown to improve cardiopulmonary risk. Overweight patients should try to achieve ideal body weight. All patients should receive preoperative instruction in coughing, deep breathing, and use of the incentive spirometer.

Respiratory infections should be treated before elective operations. Viral infections resolve with symptomatic treatment; bacterial infections can be treated with the appropriate antibiotics. Whenever possible, preoperative preparation and treatment should be performed on an outpatient basis to avoid super-infection with hospital-acquired antibiotic-resistant organisms. Adequate hydration, humidified air, and expectorants can help liquefy sputum. Postural drainage and chest percussion can help clear these secretions. Bronchodilators are often helpful for patients with chronic obstructive pulmonary disease. In addition, patients with bronchospasm or asthma may benefit from the administration of bronchodilators either by aerosol or by intermittent positive-pressure ventilation. Corticosteroids may be necessary for patients with severe asthma or pulmonary fibrosis.

No patient should be denied operation for emergent and urgent conditions because of pulmonary disease. Whenever possible, the risks should be recognized and pulmonary function optimized.

Postoperative Management

Pulmonary complications occur more commonly than cardiac complications and frequently cause prolonged hospital stays and increased morbidity and mortality. The postoperative effects of major procedures under general anesthesia include decreases in total lung capacity, vital capacity, functional residual volume, and compliance. Aggressive postoperative care minimizes these effects. Administering low doses of analgesics at frequent intervals promotes improved respiration by controlling pain without compromising respiratory drive and allows earlier ambulation and mobilization. Changing the volume of ventilation prevents atelectasis. Incentive spirometry promotes deep inspiration that can also help prevent atelectasis. Oxygen administration should be used when necessary but with judiciousness; 100% oxygen promotes atelectasis and may result in oxygen toxicity. Administering oxygen to patients with chronic hypercapnia may depress respiratory drive.

Postoperative Pulmonary Complications

Ventilatory impairment is typical after ventral thoracic and lumbar approaches to the spine. In most instances, the impairment does not prevent spontaneous breathing. However, if the operative procedures are extensive, if there has been massive trauma, if the patient is elderly, or if the patient has preexisting chronic disease or malnutrition, ventilatory impairment may be so great that a period of assisted ventilation is necessary.

The first postoperative hours are critical because this is when acute ventilatory failure most commonly occurs. The effects of muscle relaxants may not have worn off completely, and muscle weakness can cause reduced vital capacity. If a respiratory complication develops, decreased lung compliance may also contribute to inadequate ventilatory function.

Atelectasis is the most common complication in the first 2 to 3 postoperative days. It results from collapse of the most dependent portions of the lung. Clinical signs include fever, tachypnea, and tachycardia that typically develop within the first 2 postoperative days. Chest radiographs usually show linear densities in dependent segments of the lungs or frank areas of collapse. There is often radiographic evidence of volume loss in the affected lung. Treatment entails deep breathing and coughing to expand under-ventilated lung segments. The patient should be mobilized if there are no contraindications. Mechanical devices, including the incentive spirometer and devices to maintain positive airway pressure, help achieve adequate ventilation.

If the preceding methods fail to reverse atelectasis, bronchoscopy may be indicated for suctioning secretions out of the atelectatic segment. This is rarely necessary and should be used only when the atelectasis is severe and involves an entire lobe, if the patient is developing respiratory distress, or if blood gas levels are deteriorating.

Pneumonia in the postoperative patient usually results from inadequately treated atelectasis, airway contamination, or preexistent pulmonary disease, most commonly a consequence of cigarette smoking. Pneumonia rarely develops earlier than 4 to 5 days after operation unless an unusual event, such as aspiration, occurs.

The diagnosis is made by the presence of fever, leukocytosis, increased sputum production, decreased breath sounds or rales on physical examination, and a localized or diffuse infiltrate on radiographs. Gram staining of expectorated sputum usually reveals oral flora but may also show heavy colonization by a single organism and a large number of polymorphonuclear leukocytes present. If pneumonia is diagnosed, antibiotic therapy should be started immediately, on the basis of the Gram stain. Confirmatory cultures must be obtained and the antibiotic sensitivities checked. Antibiotic therapy can then be guided by these sensitivities. Therapy should include supportive care as well as measures directed at the underlying cause of the pneumonia. Oxygen saturation, respiratory rate, and work of breathing should be monitored, with endotracheal intubation and ventilation carried out if the patient’s status deteriorates.

Dyspnea, pleuritic chest pain, and hemoptysis are the classic symptoms of pulmonary embolism (PE). Patients with these symptoms or the constellation of tachypnea, tachycardia, and low-grade fever should be thoroughly evaluated for PE. Physical examination may reveal decreased breath sounds, pleural rub, or pleural effusion. Moreover, chest radiographs typically remain normal but should be obtained to rule out other causes of hypoxia. Computed tomography (CT) angiography of the chest is quick and effective at diagnosing a PE; however, pulmonary angiography remains the gold standard for diagnosis.

Pulmonary embolism accompanied by circulatory and respiratory instability mandates treatment with high-dose intravenous (IV) heparin. Placement of an inferior vena cava (IVC) filter or ligation of the IVC may be required if anticoagulants are contraindicated, if bleeding complications develop in a patient receiving anticoagulants, or if pulmonary embolism recurs in a fully anticoagulated patient.

Preoperative Evaluation

Urinary frequency and volume, dysuria, nocturia, poor stream, incontinence, and hematuria must be checked. It is important to note any history of renal disease, calculi, diabetes mellitus, or hypertension and to establish whether there has been any use of diuretics or nephrotoxins.

A history of the use of acetaminophen, a potential nephrotoxin, is particularly common in patients who undergo spine surgery. Often, patients with low back pain consume substantial quantities of acetaminophen without recognizing its potential harm. Symptoms and signs of renal disease frequently reflect the degree of renal failure; however, it is not uncommon for patients with marked impairment of renal function to be asymptomatic.

Preoperative Preparation

In the preoperative period, it is important to assess renal function carefully and correct any electrolyte abnormalities. Preoperative preparation should maximize renal function and is important for preventing postoperative failure. Urinary tract infection should be treated preoperatively with appropriate antibiotics as determined by urine culture and sensitivity tests.

Obstructive lesions of the urinary tract should be removed or corrected, if possible, before other major operations are planned. Dehydration, hypovolemia, and electrolyte imbalance should be corrected, and adequate urine volume should be ensured before surgery.

It is important to maintain all antihypertensive medications, including beta-blockers and catecholamine-depleting drugs, until the night before surgery. Discontinuation of clonidine may result in paroxysmal hypertension, and abrupt withdrawal of certain beta-blockers can produce cardiac dysrhythmia. Patients who take diuretics may require correction of volume contraction and hypokalemia. When possible, one should avoid nephrotoxic drugs and be on the alert for medications that accumulate because of decreased renal excretion. Use of nephrotoxic IV contrast media should be limited.

Postoperative Management

The diseased kidney is unable to concentrate urine and must excrete a urine volume greater than normal to rid the body of metabolic end products. At the same time, the kidney may be unable to excrete water and electrolytes. There is a slim margin between further renal insufficiency from dehydration and CHF secondary to excess salt and water retention. Effective management requires monitoring of body weight, intake and output, and serum electrolytes. Keeping track of urine electrolyte concentrations and of all measurable fluid losses helps guide appropriate fluid therapy. By themselves, however, urine output and specific gravity do not reliably reflect the state of hydration.

Nephrotoxic drugs must be administered carefully and in reduced doses to patients with impaired renal function. These agents include aminoglycoside antibiotics, cephaloridine, colistin, polymyxin B, and amphotericin B. Spot checks for urine protein are useful for detecting early aminoglycoside toxicity. Drugs requiring major dose modification in the renally impaired patient include allopurinol, digoxin, methotrexate, phenobarbital, procainamide, quinidine, and tolbutamide.

Postoperative Renal Complications

The hallmark of acute renal failure is rapidly progressive azotemia, generally accompanied by oliguria (urine output < 400 mL/24 h). Prerenal azotemia results from renal hypoperfusion caused by volume depletion (dehydration or blood loss) or decreased cardiac output from pump failure (CHF). An expeditious diagnosis of prerenal azotemia is essential because the condition is easily reversible and persistent renal hypoperfusion results in acute tubular necrosis (ATN).

The physician must assess the patient’s volume status frequently (i.e., fullness of neck veins, skin turgor, orthostatic changes in blood pressure and heart rate, and peripheral perfusion). Examination of the heart and lungs may reveal signs of CHF. Bladder catheterization can be helpful for obtaining urine specimens and monitoring urine output carefully. Measurements of serum BUN, creatinine, electrolytes, and osmolality, as well as of urine electrolytes and osmolality, can also be of diagnostic value. Following the aforementioned suggestions should help distinguish whether prerenal azotemia is secondary to hypovolemia or CHF and guide management toward resolution of the cause.

Postoperative urinary retention is a known complication for many surgical procedures, including spine surgery. Prolonged procedures typically require Foley catheter placement due to the duration of surgery and expected accumulation of high volumes of urine leading to distention or incontinence. Shorter surgical procedures may not require Foley catheterization but should not be discounted for potential urinary retention in the postoperative period. Studies have shown that up to two thirds of patients in the recovery room may not experience symptoms of bladder distention despite having more than 600 ml of urine accumulation on bladder ultrasound. The risk of urinary retention increases with age over 50, male gender, and surgical procedure. Additionally, patients with neurologic conditions, previous stroke, or spinal lesion may be predisposed to the development of postoperative urinary retention.

Causes of retention may include reflex spasm of the voluntary sphincter because of pain or anxiety, medications such as anticholinergics and narcotics, or preexisting partial bladder outlet obstruction as seen in benign prostate hypertrophy. Diagnosis of postoperative urinary retention should be made shortly after surgery to prevent long-term sequelae of overdistention. Evaluation consists of palpation of the bladder over the pubic symphysis; however, this may be unreliable, particularly in the obese patient population. Lack of voiding, combined with bladder ultrasound volumes greater than 600 mL, confirms the diagnosis.

Simple measures such as repositioning or standing may assist patients with voiding. If these maneuvers are unsuccessful, management with straight catheterization should be pursued. Serial bladder ultrasound for patients unable to void may determine the frequency of catheterization, and postvoid residuals may be assessed to ensure that patients who are able to urinate are in fact completely emptying their bladder. Medical therapy with alpha antagonists may additionally improve voiding function. If the patient cannot void spontaneously after two catheterizations and there is evidence of overstretching or mild mechanical obstruction, a Foley catheter should be left in place for 2 to 3 days before testing for spontaneous voiding again. Bladder distention should be avoided at all costs due to the long-term complications including bladder hypotonia and increased risk of bladder infections.