Preoperative Evaluation

The preoperative evaluation process by the anesthesiologist has undergone dramatic changes, in part due to health care reform and, in particular, capitated reimbursements decreasing the length of hospital stays. The increasing percentage of ambulatory surgery procedures and morning admissions the same day of surgery has changed the way we are able to evaluate patients preoperatively. The goals of the preoperative interview remain unchanged. Recommendations for laboratory tests have been established by most institutions. It is important to be cost effective and efficient while providing the optimal quality of care aimed at decreasing anesthetic morbidity and mortality. This article is an update on recent management issues in preoperative evaluation.

Purpose Of The Preoperative Evaluation

The preoperative interview is the first introduction to a patient. This initial impression is vital to establish a relationship with the patient and remains a fundamental part of the anesthesiologist's practice. Current medical trends have changed how we are able to evaluate patients preoperatively. Historically, patients were admitted the night before surgery. This allowed sufficient time for the anesthesiologist to establish rapport with the patient, conduct a thorough history and physical exam, assess and ensure the readiness for surgery, discuss the anesthetic plan, obtain informed consent, and educate the patient on the expected perioperative events. The preoperative interview has been documented to reduce patient anxiety before surgery and may even decrease postoperative pain and length of hospital stay.¹ This may be due to the patient's perceived control over the expected perioperative events he will be experiencing. Now, up to 70% of patients arrive at the hospital the morning of surgery. Patients are interviewed most commonly one to two weeks prior to surgery in a preoperative clinic or less ideally the morning of surgery. The goals of the preoperative interview remain unchanged. (Table 1). As cost containment issues continue to promote reform they must not compromise quality of care.

Table 1. Basic Standards for Preanesthesia Care
(American Society of Anesthesiologists)

These standards apply to all patients who receive anesthesia or monitored anesthesia care. Under unusual circumstances (e.g., extreme emergencies), these standards may be modified. When this is the case, the circumstances shall be documented in the patient's record.

Standard 1: An anesthesiologist shall be responsible for determining the medical status of the patient, developing a plan of anesthesia care, and acquainting the patient or the responsible adult with the proposed plan.

The development of an appropriate plan of anesthesia care is based upon

Reviewing the medical record
Interviewing and examining the patient to
a. Discuss the medical history, previous anesthetic experiences, and drug therapy
b. Assess those aspects of the physical condition that might affect decisions regarding perioperative risk and management
Obtaining and/or reviewing tests and consultations necessary to the conduct of anesthesia
Determining the appropriate prescription of preoperative medications as necessary to the conduct of anesthesia

The responsible anesthesiologist shall verify that the above has been properly performed and documented in the patient's record.

American Society of Anesthesiologists, Approved by House of Delegates on October 14, 1987.²

Role Of The Anesthesiologist

The preoperative evaluation should be performed by an anesthesiologist. Training is required to understand the physiological changes of surgery. What is determined to be medically optimized for daily life by may not be adequate for the stress of major surgery. With the increasing age of our population, patients are presenting for surgery with more complex medical problems. Significant predictors of postoperative morbidity and mortality include patient's age, preoperative physical status as defined by the American Society of Anesthesiologists (ASA) classification (Table 2), type of surgery (major vs. minor), and the nature of surgery (emergent vs. elective).^5,6 Surgery is a major insult on the human body regardless of the anesthesia provided. The information obtained from the patient preoperatively is used to devise a safe anesthetic plan. The anesthetic agents we plan for intra-operatively are aimed at minimizing the body's stress response to surgery, maintaining homeostasis while considering the patient's chronic medical problems, managing fluid shifts and losses, and providing postoperative pain control. The decreasing incidence of anesthetic morbidity and mortality over the past decades has coincided with the advent of new monitors such as pulse oximetry and capnography, the adoption of practice standards, and new pharmacological agents.

Table 2. The American Society of Anesthesiologists Classification of Physical Status
ASA Class I ASA Class II ASA Class III ASA Class IV ASA Class V E	A normal healthy patient A patient with mild systemic disease A patient with severe systemic disease that limits activity, but is not incapacitating A patient with incapacitating systemic disease that is a constant threat to life A moribund patient not expected to survive 24 hours with or without surgery Designates an emergency surgical procedure
American Society of Anesthesiologists Newsletter. 1963.³

Screening Questionnaires

Many institutions have developed questionnaires in order to improve efficiency in preoperative clinics. To assist the preoperative process, they may help as a guide to more focused questioning during the history. Videos have also been used for patient education on perioperative events. Research is conflicting over the benefits of both of these preoperative tools.^7,8 In a hybrid preoperative clinic of residents, primary care physicians, and anesthesiologists, screening questionnaires provided a more efficient use of medical personnel in their preadmission clinic.⁹

The Impact Of The Change In Anesthetic Management By The Preoperative Interview

In efforts to streamline the preoperative process some have suggested that healthy patients can be evaluated the morning of surgery. In a retrospective study, Gibby et al, reviewed the preoperative evaluation records of previously healthy patients seen in the preoperative clinic. They found 20.1% of patients had medical problems identified preoperatively that changed anesthetic management. Medical problems that led to a change included a history of reflux, asthma, diabetes mellitus, rheumatoid arthritis, history of a stroke, and the identification of a difficult airway.¹⁰ Anticipating medical problems that may increase morbidity and mortality should reduce risk. Early detection of these problems can avoid last minute OR delays such as the need to treat with H2 blockers or B-2 agonists, check blood glucose, order additional lab tests, or obtain equipment in the OR for an anticipated difficult intubation.

Laboratory Testing

Multiple factors led to the need to revise preoperative laboratory testing. When a patient entered the hospital, it was common to order a routine battery of tests before performing the history and physical exam. This shotgun approach to ordering labs especially in healthy asymptomatic patients is not ideal for a number of reasons. The use of routine testing in asymptomatic healthy patients is not beneficial or cost effective.^11-14 A physician should consider the risk-benefit ratio of any lab that is ordered. When studying a healthy population, 5% of patients will have results which fall outside the normal range. There may be added risk to the patient while confirming that an abnormal test is not of significance. There are also medicolegal implications of not pursuing an abnormal test. For example, an asymptomatic 34-year old health male presents for cholecystectomy and a "routine screening" preoperative CXRAY demonstrates an abnormality. Further work-up such as CT scan, bronchoscopy, or possible biopsy of the lesion presents obvious risk to the patient with the low yield of the abnormality being of significance. However, if the CXRAY is ignored and later found to be a malignancy, it could have medicolegal consequences. Thus, lab tests should be ordered based on information obtained from the history and physical exam, the age of the patient, and the complexity of the surgical procedure.

Specific Hematological Tests

Routine hematocrit testing is not recommended in healthy males less than 65 years of age.^11-15 History and physical exam should guide in the determination to order a hematocrit level. Chronic normovolemic anemia is generally well-tolerated and not found to be associated with increased anesthetic morbidity and mortality for elective minor surgery; however, it may not be justified to proceed with elective surgery with anemia of unknown cause. Uncontrolled polycythemia vera is related to increased risk of perioperative complications indicating the need to diagnose and control polycythemia preoperatively.¹⁵ Indications for hematocrit testing based on history and physical exam include all menstruating females, suspected anemia, signs of polycythemia, chronic illness, cardiac disease, pulmonary disease, renal disease, malignancy, children less than one year of age with possible sickle cell disease, age greater than 65 years of age, and a surgical procedure with expected blood loss. Additional tests such as ECG, CXRAY, electrolytes, PT/PTT, platelet count, bleeding time, creatinine, glucose, LFT's, or pregnancy screen should be ordered based on the patient's preoperative condition (Table 3).

Preoperative Cardiac Assessment

Who needs a preoperative electrocardiogram (ECG)?

Recommendations for the use of preoperative ECG testing in healthy asymptomatic patients are based on the two factors that increase a patient's cardiovascular risk which are increasing age and male gender. Most institutions recommend preoperative ECGs for male patients greater than 40-45 years of age and female patients greater than 50 years of age. Additional risk factors for cardiac disease identified during the history that would warrant a preoperative ECG include hypertension, hypercholesterolemia, cigarette use, diabetes, obesity, positive family history for coronary artery disease, pulmonary disease, CNS disease, a history of radiation therapy, and ETOH or illicit drug abuse.

Abnormalities on ECG that may change anesthetic management or indicate the need for further work-up include rhythm disturbances, conduction abnormalities, atrial flutter, atrial fibrillation, left ventricular hypertrophy, premature ventricular contractions, WPW, and signs of ischemia or infarction.

Due to the frequency of detection of new abnormalities on ECG, Rabkins et al, recommend the ECG should be recent, preferably within the last two months.⁵

Preoperative Evaluation Of Patients With Cardiac Disease Presenting For Non-Cardiac Surgery

In patients with suspected cardiac disease the history and physical exam should be directed to evaluate the presence of congestive heart failure, coronary artery disease, cardiomyopathy, valvular heart disease, hypertension, or any rhythm disturbances. The most significant preoperative cardiac risk factor of postoperative morbidity and mortality is the presence of congestive heart failure. Hypertension is a risk factor for the development of CAD and a major cause of congestive heart failure, renal failure, and cerebrovascular disease. Patients with untreated or poorly controlled hypertension have increased intraoperative hemodynamic lability and an increased risk in the presence of a preoperative diastolic blood pressure >110mmHg.

The American College of Cardiology (ACC) and the American Heart Association (AHA) published a task force report on Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery. The purpose as stated in the report is to provide a framework for considering cardiac risk of noncardiac surgery in a variety of patients and operative situations. The approach to a patient with cardiac disease should be the same as in a non-surgical setting; however, the scheduling of tests may be expedited in view of the urgency of the surgery, patient's risk factors, and other surgical considerations.¹⁷ The task force identified only a small percentage of patients who benefit from coronary artery revascularization surgery in order to proceed with an elective surgery.

A step wise approach of the preoperative cardiac assessment is described in the report (Figure 1 -- available in PDF format). The factors which guide decision making in the figure include the patient's cardiovascular risk (major predictors, intermediate predictors, or minor predictors), the functional capacity of the patient, and the surgery specific risk.

When is a cardiology consult indicated? A consultant may assist in the acute treatment of patients demonstrating any signs of unstable angina, decompensated congestive heart failure, significant arrhythmias, or severe valvular disease. Also, they can recommend non-invasive or invasive testing to define the presence or extent of cardiac disease.

Medico-Legal Issues

One of the best defenses we have for the prevention of litigation after providing quality care is a thorough preoperative evaluation. Patients are less likely to initiate litigation against a physician viewed as compassionate and who took time to explain the risks and benefits of a procedure. A study by Ali, et al identified that 26.9% of patients were not able to recall a preoperative interview. Preoperative assessment is also targeted by malpractice attorneys with lawsuits addressing inadequate preoperative assessment. These issues only serve to emphasize the important role of a preoperative evaluation which is to establish a rapport with the patient, perform a thorough history and physical exam, use the information to guide further laboratory testing, devise a safe anesthetic plan, discuss anesthetic options with the patient, educate the patient on perioperative events and obtain informed consent.