Chapter 4 Preoperative Pitfalls

Aimee M. Crago, MD, PhD, Stephen R.T. Evans, MD

INTRODUCTION

Although the hospital course of a patient is affected profoundly by what happens inside the operating room, many complications can be prevented by adequate preoperative preparation. Rates of postoperative myocardial infarction, decomposition of congestive heart failure, pneumonia, bleeding, and infection are all affected by identification of a patient’s individual risk factors and medical optimization of the patient’s condition prior to surgery. A clear history and physical examination, reconciliation of a patient’s medication list, and consultation with appropriate specialists are the first steps in ensuring that an operation will go as smoothly as possible, and that hospital length of stay and preoperative morbidity and mortality rates are maintained at a minimum.

INDICATIONS

The surgeon should complete a mental, if not physical, checklist of preoperative risk factors and appropriate interventions for each patient who is scheduled for the operating room. There are no exceptions to this dictum. Even in emergent situations, knowledge of the patient’s comorbidities should be elucidated as soon as possible to aid in intraoperative and postoperative care.

PREOPERATIVE EVALUATION

Neurologic Evaluation and Assessment of Pain Susceptibility

Failure to Recognize Carotid Disease

Failure to Recognize Low Pain Threshold

• Consequence

Tachycardia, pneumonia, and opioid withdrawal are consequences of failure to recognize low pain threshold. Chronic pain patients are often recognized at presentation for elective general surgery procedures. These patients develop tolerance to opioids, and hyperalgesia manifests as increased sensitivity to pain and high analgesia requirements compared with those in opioid-naïve patients. Excessive pain increases the risk of both postoperative pulmonary (owing to splinting and poor mobilization) and cardiac complications. Patients inadequately treated may develop symptoms of nausea, vomiting, and hemodynamic instability consistent with narcotic withdrawal.

Grade 1 complication

• Intervention

Opioid dosing remains the mainstay of postoperative pain control. However, the use of adjuvant therapies, such as those presented in Table 4-1, has been shown to reduce opioid requirements and may aid in treatment of postoperative pain in patients with chronic pain. Intravenous (IV) narcotics should be used to treat symptoms of opioid withdrawal.⁵

Table 4-1 Alternative to Intravenous Narcotics in the Postoperative Patient

Drug	Contraindications/Side Effects
Nonsteroidal anti-inflammatory drugs (e.g., ketorolac)	Renal dysfunction/acute renal failure
Dextromethorphan	Seizure, arrhythmia, brain damage
Cyclo-oxygenase 2 inhibitors	Cardiovascular disease, renal dysfunction/acute renal failure, gastrointestinal bleeding
Acetaminophen	Hepatic dysfunction
Neurontin	Somnolence, dizziness, fatigue
Local anesthetic	Seizure, arrhythmia
Ketamine	Psychotropic effects
Peripheral nerve block • Axillary nerve block • Supraclavicular nerve block • Interscalene nerve block • Paravertebral nerve block • Lumbar plexus block • Femoral nerve block • Sciatic nerve block	Seizure, arrhythmia
Epidural anesthesia	Seizure, arrhythmia, hypotension

• Prevention

A patient’s daily dosage of narcotics as well as expectations for postoperative pain should be discussed prior to surgery, and a perioperative pain regimen should be planned between patient, surgeon, and anesthesiologist. Standing doses of preoperative pain regimens should not be stopped pre- or perioperatively. In the case of gastrointestinal (GI) surgeries, oral medications should be substituted with IV equivalents after surgery to prevent withdrawal.⁵ In addition, patients will require supplemental narcotics, two to four times the doses required by opioid-naïve patients, for adequate pain control.^6,⁷ Narcotics can, in part, be effectively administered by continuous infusion through patientcontrolled analgesia (PCA), which will also provide an efficient means for delivery of supplemental drugs.⁵

Adjuvant therapies such as those outlined in Table 4-1 have been shown to reduce postoperative opioid requirements in patients with chronic pain. Of note, epidurals should utilize lipophilic narcotics because these are more effective in patients with chronic pain and should not replace IV narcotics because such management could result in withdrawal. Partial opioid agonists such as buprenorphine or nalbuphine should also be avoided because they too may cause withdrawal.⁵

Transition to an oral regimen provides another challenge for patient and clinician. The equivalent to the daily postoperative narcotic requirement can be calculated (Table 4-2) and prescribed in part (generally one half the requirement) as long-acting oral opioids such as oxycodone or methadone. Intermittent breakthrough doses of short-acting medications can be prescribed to fulfill the remainder of the daily requirement and can be slowly tapered to return the patient to his or her baseline narcotic regimen over a 2- to 4-week period.⁵

Table 4-2 Commonly Used Narcotics and Their Approximate Conversion

Drug	Oral Dose	Intravenous Dose
Hydrocodone	30 mg q3h	—
Hydromorphone	7.5 mg q3h	1.5 mg q3h
Fentanyl	—	0.1 mg q1h
Meperidine	300 mg q3h	100 mg q3h
Morphine	30 mg q3h	10 mg q3h
Oxycodone	30 mg q3h	—

Failure to Recognize Alcohol Dependence

• Consequence

Alcohol withdrawal syndrome (characterized by tremor, insomnia, agitation, hypertension, diaphoresis, fever, nausea, vomiting, and hallucinations) may precede delirium tremens (DT) and result in cognitive change, hallucination, and seizure. Alcohol dependence is common in surgical patients. Patients with cancers of the oropharynx and GI tract often have comorbid alcohol dependence, and more than one third of trauma patients may be alcohol dependent. Less than one quarter of these patients are recognized preoperatively or on admission, resulting in high rates of withdrawal symptoms and requiring admission to the intensive care unit (ICU) for hemodynamic and neurologic monitoring as well as aggressive medical intervention.⁸

Grade 1/4/5 complication

• Intervention

Multiple meta-analyses have looked at the treatment of patients with alcohol withdrawal and DT. Sedativehypnotic drugs, generally benzodiazepenes, appear to be the most effective medications for preventing alcohol withdrawal seizures and related mortality once symptoms of withdrawal occur. The choice of benzodiazepene is based on desired onset and duration of action, with IV dosing providing the most rapid effect, and long-acting medications being associated with fewer breakthrough symptoms but higher rates of oversedation. Intermittent doses of diazepam or lorazepam can be repeated until sedation is achieved and then administered hourly to maintain sedation.⁹ Affects of benzodiazepine and adjuvant medications should be titrated for light sedation (patient is easily aroused from sleep) against an objective sedation scale such as the Ramsey Sedation Score¹⁰ or the Richmond Agitation-Sedation Scale¹¹ (Box 4-1). Patients can be weaned from treatment medications by titrating for symptoms evaluated in relation to these tools.

Box 4-1 Sedation Scales

Adapted from Ramsey MAE, Savege TM, Simpson BRJ, et al. Controlled sedation with alphaxalanoe-alphadolone. BMJ 1974;2:656–659; and from Sessler C, Gosnell M, Grap MJ, et al. The Richmond agitation-sedation scale. Validity and reliability in adult intensive care patients. Am J Respir Crit Care Med 2002;166:1338.

Richmond Agitation-Sedation Scale (RASS)

+4 Combative	Overtly combative or violent, immediate danger to staff
+3 Very agitated	Pulls on or removes tubes or catheters, aggressive behavior toward staff
+2 Agitated	Frequent nonpurposeful movement or patient-ventilator dyssynchrony
+1 Restless	Anxious or apprehensive but movements not aggressive or vigorous
0 Alert and calm
− 1 Drowsy	Not fully alert, sustained (>10 sec) awakening, eye contact to voice
− 2 Light sedation	Briefly (<10 sec) awakens with eye contact to voice
− 3 Moderate sedation	Any movement (but no eye contact) to voice
− 4 Deep sedation	No response to voice, any movement to physical stimulation
− 5 Unarousable	No response to voice or physical stimulation

Prescription of clonidine, haldol, or propofol for persistant symptoms can be beneficial as an adjunct to benzodiazepenes, but these drugs have not been shown to prevent seizure when given as monotherapy.^8,⁹ Supplementation of IV fluids with magnesium, thiamine, and folate can correct deficiencies seen in many patients with alcohol dependence.

• Prevention (Fig. 4-2)

A thorough history will elicit a history of alcohol use in many patients with symptoms of liver disease. Laborotory values may be helpful in that elevated liver function tests and γ-glutamyltransferase (GGT) may confirm suspected alcohol use. Alcoholic patients may be anemic with a high mean corpuscular volume (MCV). The CAGE questionnaire (Box 4-2) is commonly applied to identify those patients with suspected alcohol dependence.¹² Answering yes to three of the CAGE questions is strongly correlated with alcohol dependence, and patients who do so should be placed on perioperative DT prophylaxis. Affirmative answers to any of the CAGE questions or laboratory values suggestive of alcohol dependence should prompt consideration of postoperative prophylaxis, as should an elevated blood alcohol level measured on admission of a trauma patient.⁸

Figure 4-2 Algorithm for prevention and management of alcohol withdrawal in the surgical patient.

Standard dosing regimens for prophylaxis include regular administration of diazepam or lorazepam. Again, haldol and clonidine can be employed for breakthrough symptoms, and patients should be monitored for signs of psychomotor agitation, hemodynamic instability, and cognitive changes.⁸

Cardiac Risk Assessment and Preoperative Optimization

Failure to Recognize or Medically Optimize the Patient with Ischemic Heart Disease or Congestive Heart Failure

• Consequence

Myocardial infarction (MI) and congestive heart failure (CHF) seen as consequences of subsequent left ventricular dysfunction. Physiologic stress related to operative procedures and altered rapid eye movement (REM) sleep secondary to anesthesia are known to be associated with postoperative MI. In high-risk populations, rates of postoperative MI have historically approached 50%. Risk factors for a postoperative cardiac event were first described by Goldman and colleagues in 1977,¹³ but these have been refined in numerous studies, as described later.

Grade 1/4/5 complication

• Intervention

Treatment for patients with postoperative MI centers on reduction of oxygen demand and decrease in afterload. β-Blockers reduce heart rate and have been shown to have a positive effect on mortality after MI. Nitroglycerin dilates coronary arteries and improves oxygen delivery to the myocardium in patients with ongoing discomfort. This drug also treats CHF and hypertension. Aspirin is indicated in the setting of acute MI, and supplemental oxygen should be prescribed. Patients with ongoing chest pain or hemodynamic instability should be evaluated for emergent cardiac catheterization.¹⁴ The risk of bleeding associated with fibrinolytic therapy makes this option less feasible in the postsurgical patient than in the general population of cardiac patients.

Patients with symptoms of fluid overload and CHF may require ionotropic agents such as dopamine or placement of an intra-aortic balloon pump. Diuretics are appropriate for preventing pulmonary edema. These drugs should also be administered to patients with CHF recognized preoperatively and who are experiencing episodes of postoperative decompensation.

• Prevention

Patients should undergo a complete preoperative history and physical examination. Those with cardiac symptoms or over age 40 require a baseline echocardiogram. This evaluation is aimed at identifying factors contributing to perioperative cardiac risk and was published in the American College of Cardiology/American Heart Association Guidelines for Perioperative Cardiac Evaluation for Noncardiac Surgery (Tables 4-3 and 4-4). Based on this risk stratification and the risk of the planned procedure (see Table 4-3), indications for further preoperative testing can be easily identified (see Table 4-4). With few exceptions, patients with only minor risk factors can generally undergo surgery without further testing whereas those with major risk factors may require preoperative coronary angiography and medical optimization. Patients at intermediate risk for surgery have traditionally been advised to undergo noninvasive testing in the form of exercise or chemical stress tests to further stratify their perioperative risk of MI. If reversible perfusion defects are observed on stress testing, coronary angiography before intermediate or high-risk procedures is advisable.^15,¹⁶

Table 4-3 Preoperative Cardiac Risk Stratification

Rights were not granted to include this table in electronic media. Please refer to the printed book.

Adapted from recommendations in Eagle KA, Berger PB, Calkins H, et al. ACC/AHA Guideline Update for Perioperative Cardiovascular Evaluation for Noncardiac Surgery—executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). Circulation 2002;105:1257–1267.

Table 4-4 Preoperative Evaluation for Ischemic Heart Disease

Rights were not granted to include this table in electronic media. Please refer to the printed book.

β-Blockade has become the mainstay of pharmacotherapy for prevention of postoperative MI. In randomized, prospective studies, patients at risk for cardiac events were given β-blockers in the perioperative period and had reduced incidences of ischemic events and mortality.¹⁷^–¹⁹ This has been borne out in a recent meta-analysis.²⁰ When patients are stratified according to the Revised Cardiac Risk Index (Box 4-3), those with three risk factors clearly benefit from preoperative β-blockade in conjunction with high-risk procedures; those with no risk factors do not require the drug.^21,²² Intermediate-risk patients are likely helped and, in the absence of clear contraindications, should be prescribed the drugs. In the context of widespread prescription of β-blockers, risks of perioperative cardiac complications have significantly decreased. In fact, a contemporary study suggested that preoperative stress tests may no longer benefit patients at intermediate risk because revascularization does not improve outcomes after high-risk surgery in certain populations but simply delays the timing of the procedure.²³ In a manner similar to that of β-blockers, recent evaluation of α₂-agonists suggests that these medications may prevent perioperative cardiac events.²⁰

Box 4-3 Revised Cardiac Risk Index (Indications for Preoperative β-Blockers)

Rights were not granted to include this box in electronic media. Please refer to the printed book.

Adapted from Lee TH, Marcantanio ER, Mangione CM, et al. Derivations and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation 1999;100:1043–1049.

Special attention should be paid to patients with a preoperative diagnosis of CHF. These patients should have a preoperative echocardiogram to delineate function of the ventricles. Fluid resuscitation should be carefully monitored and diuretics used to increase urine production during remobilization (postoperative day 2–3). Stopping these medications postoperatively when patients take them on a regular basis can result in oliguria because renal function is often dependent on loop diuretics after long-term use.