Perioperative Evaluation

Lopa Dalmia

Andrea D. Cass

Advances in perioperative risk assessment, surgical and anesthetic techniques, and better implementation of medical therapy have served to decrease the frequency of complications associated with noncardiac surgery. This has led to a decline in operative mortality over the last 10 to 20 years (1). It is estimated that the number of persons older than 65 years in the United States will increase (25% to 35%) over the next 30 years. This is the same age-group in which the largest number of surgical procedures is performed. Thus, it is conceivable that the number of noncardiac surgical procedures performed will increase from the current 6 million to nearly 12 million per year (1). The financial implications of risk stratification cannot be ignored, and the need for thorough and efficient perioperative risk evaluation is warranted.

The podiatric surgeon, internist, and anesthesiologist are key players in determining perioperative risk for each patient prior to surgery. A thorough perioperative medical assessment can decrease the length of hospital stay as well as minimize postponed or canceled surgeries (2). A methodical approach in evaluating the severity and stability of the patient’s medical condition is the cornerstone perioperative risk assessment.

The risk of perioperative morbidity and mortality is strongly related to physiologic stress induced by surgery. Foot and ankle surgery is considered to be low to intermediate risk by the American College of Cardiology (ACC) (2). A problem-focused perioperative medical assessment involves a history and physical examination, focusing on risk factors for cardiac, pulmonary, and infectious complications, and determination of a patient’s functional capacity (discussed below). This chapter outlines specific components of perioperative evaluation and offers guidelines for perioperative risk assessment.

PHYSIOLOGIC EFFECT OF SURGERY

Epinephrine, norepinephrine, and cortisol levels increase during surgery and remain elevated for 24 to 72 hours (3). Serum antidiuretic hormone levels may be elevated for up to 1 week postoperatively. There is evidence that anesthesia and surgery may be associated with a relative hypercoagulable and inflammatory state mediated by increases in plasminogen activator-1, factor VIII, and platelet reactivity and increased levels of tumor necrosis factor, interleukin-1 and interleukin-6, and C-reactive protein (3). The body restores hemostasis after surgery and for those patients with medical comorbidities, the recovery is complicated with postoperative complications. As physicians, it is our duty to recognize and understand the patient in the preoperative phase to avoid postoperative complications.

PREOPERATIVE HISTORY AND PHYSICAL EXAMINATION

Preoperative assessment for elective surgery is typically performed days before surgery. It entails a thorough review of patient’s history, drug history, surgical and anesthetic history, alcohol and tobacco use, allergies, bleeding history, functional class, and physical examination.

HISTORY

The history includes information about the condition for which the surgery is planned, any past surgical procedures, patient’s experience with anesthesia, and chronic medical conditions, particularly of the heart and lungs. In children, the history includes birth history, focusing on risk factors such as prematurity at birth, perinatal complications and congenital chromosomal or anatomic malformations, and history of recent infections, particularly upper respiratory infections or pneumonia.

MEDICATIONS

Medications (with dosages), including over-the-counter medications and herbal medicines, are noted. Drug dosages may need to be adjusted in the perioperative period. Table 5.1 lists preoperative recommendations of cardiovascular, pulmonary, diabetes, and other medications (4). Immunization status can be documented, and vaccines can be updated if necessary.

ALLERGIES

A latex allergy is uncommon and occurs in 5% to 10% of the population (1). Patients with a history of chronic urologic problems, spina bifida, and atopic dermatitis are considered at high risk for latex allergy. An allergy to antibiotics, pain medications, metal, and adhesive tapes are common. It is important to obtain information about the type of reaction the patient experienced with the specific allergen.

SOCIAL HISTORY

Smoking, alcohol, and drug use history are important to reduce perioperative pulmonary complications (5). A study of
811 patients who had hip and knee arthroplasty demonstrated that smoking was the single most important risk factor for the development of postoperative cardiopulmonary complications and delay in wound healing. These complications often lead to a delay in discharge from the hospital (>15 days) (5).

TABLE 5.1 Pharmacologic Categories and Their Recommendations

FREQUENTLY USED MEDICATIONS
Acetaminophen		Continue use
Aspirin		Hold 7-10 d prior to surgery
			Due to irreversible inhibitor activity of platelet cyclooxygenase
NSAIDs		Hold 3 d prior to surgery
			Due to reversible inhibitor activity of platelet cyclooxygenase
Clopidogrel		Hold 7-10 d prior to surgery
			Due to its irreversible antiplatelet effect
CARDIOVASCULAR MEDICATIONS
Digoxin	}
Clonidine
Beta-blockers		Continue up to and including day of surgery
Calcium channel blockers
Diuretics	}	Hold on the morning of surgery
ACE inhibitors			Especially if indication is CHF because there is an increased risk of hypotension during surgery
Angiotensin II receptor blocker
Cholesterol-lowering drugs	Hold 1 d prior to surgery
		Carry risk of rhabdomyolysis and myositis
PULMONARY MEDICATIONS
Inhaled beta-agonist	}
Inhaled ipratropium		Continue up to and including day of surgery
Inhaled corticosteroid
DIABETES MEDICATIONS
Insulin		Give long-acting insulin at 1/2 the normal dose, hold short-acting morning of surgery
Metformin		Hold 2 d prior to surgery
			Due to risk of lactic acidosis if patient has renal problems preoperatively
Sulfonylureas
Thiazolidinediones	}	Hold on the morning of surgery
Alpha-glucosidase inhibitors
VITAMINS
Vitamin E supplements			Hold 7-10 d prior to surgery
			Due to a risk of bleeding

Smoking has a known detrimental effect on healing bone and tissue. It has been associated with intervertebral disc disease and low back pain. Further, nicotine causes delay in tendon-to-bone healing in animal models (6). The patient should quit smoking 8 or more weeks before surgery to minimize the surgical risk associated with smoking (7).

LABORATORY TESTING

Preoperative laboratory testing should be selective and not routine. Current recommendations are for laboratory tests based on the specific signs, symptoms, and diagnosis (8). Normal laboratory test results obtained 4 to 6 months before surgery may be used as preoperative tests, provided there are no changes in the clinical status of the patient. MacPherson et al found that less than 2% of test results conducted 4 months before surgery had changed at the time of clinical evaluation (9). Preoperative laboratory studies include a complete blood count, extensive blood chemistry profile, coagulation profile, urinalysis, electrocardiogram (ECG), and chest radiographs. Indications for specific tests are as follows:

Urine pregnancy test should be considered for women of childbearing age.
Chemistry profile should be performed in patients with a history of hypertension, diuretic use, chronic obstructive pulmonary disease (COPD) or obstructive sleep apnea, diabetes, renal disease, or chemotherapy.
Complete blood count should be performed in patients with a history of fatigue, dyspnea on exertion, liver disease, blood loss, signs of coagulopathy, or tachycardia.
Coagulation profile is indicated if the patient is receiving anticoagulant therapy, has a family or personal history that suggests a bleeding disorder, or has evidence of liver disease (8).
Renal and liver function tests are indicated for patients who have a medical condition or medication use that would serve as indications for these tests.
ECG is generally recommended in men over the age of 40 years, in women older than 50 years, and in those with known underlying cardiovascular disease (8).
Chest radiographs should be obtained if there are signs of pulmonary disease.

PERIOPERATIVE ANESTHESIA ASSESSMENT

The American Society of Anesthesiologists (ASA) in 1987 adopted basic standards for the evaluation of patients prior to surgery. These standards require the anesthesiologist to determine the medical status of the patient by developing a plan of anesthetic care. The ASA classification was designed to estimate overall mortality risk in patients undergoing surgery, but a number of studies have shown that it also predicts cardiovascular and pulmonary complications. Patients who are graded higher than class II in the five-class ASA system have a two- to threefold increased risk of postoperative pulmonary complications compared with those graded class II or lower. Although subjective, a score of II to V indicates an increased level of severity and increased postoperative morbidity (Table 5.2) (10).

Anesthesia and surgery are coupled with physiologic response to preserve homeostasis. Homeostasis is carefully monitored through the perioperative period. Inhaled, intravenous, and local anesthesia cause diverse effects on the nervous, cardiovascular, and respiratory systems.

TABLE 5.2
Preoperative Anesthesia Assessment: American Society of Anesthesiology (ASA) Classification

Class I	A normal, healthy patient e.g., healthy with good exercise tolerance
Class II	A patient with mild systemic disease e.g., controlled hypertension or controlled diabetes without systemic effects, cigarette smoking without COPD, anemia, mild obesity, age younger than 1 y or older than 70 y, pregnancy
Class III	A patient with severe systemic disease e.g., controlled CHF, stable angina, old MI, poorly controlled hypertension, morbid obesity, bronchospastic disease with intermittent symptoms, chronic renal failure
Class IV	A patient with severe systemic disease that is a constant threat to life e.g., unstable angina, symptomatic COPD, symptomatic CHF, hepatorenal failure
Class V	A patient with a critical medical condition with little chance of survival with or without the surgical procedure
	e.g., multiorgan failure, sepsis syndrome with hemodynamic instability hypothermia, poorly controlled coagulopathy
Class VI	A declared brain dead patient who is undergoing anesthesia care for the purposes of organ donation
E	If the procedure is an emergency, the physical status is followed by “E” (e.g., “2E”)
Modified from the American Society of Anesthesiologists, last amended October 1984.

Inhalational anesthetic agents have predictable physiologic effects. All inhalational anesthetic agents are myocardial depressants. While not clinically significant in healthy patients, this effect leads to a dependence on cardiac preload that may cause an accentuated response to the induction of anesthesia in patients who are volume depleted due to illness or overdiuresis or who have left ventricular dysfunction. Anesthesia leads to a decrease in lung volumes, which may lead to atelectasis and is a principal factor leading to the development of postoperative pulmonary complications (3).

Controversy exists regarding the relative safety of general versus spinal or epidural anesthesia in patients at risk for postoperative cardiac or pulmonary complications. In a recent large meta-analysis of randomized controlled trials of anesthetic technique, patients who were randomized to receive spinal or epidural anesthesia as a component of their anesthesia had significantly lower rates of venous thromboembolism, pneumonia, respiratory depression, myocardial infarction (MI), or death than patients receiving general anesthesia exclusively (11,12). In general, the choice of anesthetic technique or agent, the decision to use invasive hemodynamic monitoring, and the regulation of body temperature should be left to the anesthesiologist. (See Chapter 7 on anesthesia for a detailed review of perioperative anesthesia).

PERIOPERATIVE CARDIAC ASSESSMENT

Cardiac complications create one of the most significant risks to patients undergoing noncardiac surgery. A study published in 1977 reported the overall risk of cardiac complications and cardiac death to be 5.8%, although the rates differ when various parameters are included (3). This makes understanding a patient’s cardiovascular status essential to help reduce these sometimes fatal complications.

Cardiac risk stratification prior to noncardiac surgery serves a number of goals (13). First is to determine the patient’s current health status, followed by the establishment of a surgicalrisk profile. It will also help to determine whether further cardiac testing is indicated and to identify the actions that might reduce the patient’s perioperative risk.

Over the years, there have been multiple indices devised to help surgeons better understand the cardiac risk of a patient undergoing noncardiac surgery. The most widely excepted index was developed in 2002 by the ACC/American Heart Association (AHA) and will be discussed here (10). These guidelines recommend that three elements be assessed, including patient-specific clinical variables, exercise tolerance (also known as functional capacity), and surgery-specific risk. Podiatric surgery is generally grouped with orthopaedic surgery in the low- to intermediate-risk group.

The 2002 ACC/AHA guidelines on perioperative cardiovascular evaluation for noncardiac surgery summarized clinical predictors of increased perioperative risk for MI, heart failure (HF), and cardiac death. These clinical predictors are derived from the history, physical examination, and resting ECG and are divided into major, intermediate, and minor predictors. Major predictors require intensive management, which may cause a delay or cancellation of surgery. These include recent MI (within 6 months), severe angina, recent percutaneous coronary intervention, and significant arrhythmias. Intermediate predictors may necessitate further noninvasive workup and
include mild angina, prior MI by history of ECG, rhythm other than sinus, decompensated HF, diabetes mellitus, and renal insufficiency. Minor predictors are recognized markers for cardiovascular disease but have not been proven to increase perioperative risk. These include advanced age, abnormal ECG, rhythm other than sinus, low functional status, history of stroke, and uncontrolled systolic hypertension.

A thorough history is important in order obtain pertinent information of a patient’s cardiovascular status including a history of MI, congestive heart failure (CHF), arrhythmias, or valvular disease. It is also important to ascertain any diagnostic or therapeutic procedures the patient has undergone for these conditions, when they were performed, and the specific results (14).

Only gold members can continue reading. Log In or Register to continue