Principles of Preoperative and Operative Surgery

Principles of Preoperative and Operative Surgery Sabiston 2007 Presented in April 2008 By Dr. S. Noorshafiee

Preoperative Preparation of the Patient • Systems Approach to Preoperative Evaluation • Additional Preoperative Considerations • Preoperative Checklist

PREOPERATIVE PREPARATION OF THE PATIENT • The modern preparation of a patient for surgery is epitomized by the convergence of the art and science of the surgical discipline. The context in which preoperative preparation is conducted ranges from an outpatient office visit to hospital inpatient consultation to emergency department evaluation of a patient.

Approaches to preoperative evaluation differ significantly, depending on the nature of the complaint and the proposed surgical intervention, patient health and assessment of risk factors, and the results of directed investigation and interventions to optimize the patient's overall status and readiness for surgery.

This chapter reviews the components of risk assessment applicable to the evaluation of any patient for surgery and attempts to provide some basic algorithms to aid in the preparation of patients for surgery.

Determining the Need for Surgery • Patients are often referred to surgeons with a suspected surgical diagnosis and the results of supporting investigations in hand. In this context, the surgeon's initial encounter with the patient may be largely directed toward confirmation of relevant physical findings and review of the clinical history and laboratory and investigative tests that support the diagnosis.

A recommendation regarding the need for operative intervention can then be made by the surgeon and discussed with the patient's family members. A decision to perform additional investigative tests or consideration of alternative therapeutic options may postpone the decision for surgical intervention from this initial encounter to a later time

It is important for the surgeon to explain the context of the illness and the benefit of different surgical interventions, further investigation, and possible nonsurgical alternatives, when appropriate

The surgeon's approach to the patient and family during the initial encounter should be one that fosters a bond of trust and opens a line of communication among all participants. A professional and unhurried approach is mandatory, with time taken to listen to concerns and answer questions posed by the patient and family members.

The surgeon's initial encounter with a patient should result in the patient being able to express a basic understanding of the disease process and the need for further investigation and possible surgical management. A well-articulated follow-up plan is essential.

Perioperative Decision Making • Once the decision has been made to proceed with operative management, a number of considerations must be addressed regarding the timing and site of surgery, the type of anesthesia, and the preoperative preparation necessary to understand the patient's risk and optimize the outcome.

These components of risk assessment take into account both the perioperative (intraoperative period through 48 hours postoperatively) and the later postoperative (up to 30 days) periods and seek to identify factors that may contribute to patient morbidity during these periods.

Preoperative Evaluation • The aim of preoperative evaluation is not to screen broadly for undiagnosed disease but rather to identify and quantify any comorbidity that may have an impact on the operative outcome

This evaluation is driven by findings on the history and physical examination suggestive of organ system dysfunction or by epidemiologic data suggesting the benefit of evaluation based on age, gender, or patterns of disease progression. The goal is to uncover problem areas that may require further investigation or be amenable to preoperative optimization

Routine preoperative testing is not cost-effective and, even in the elderly, is less predictive of perioperative morbidity than the American Society of Anesthesiologists (ASA) status or American Heart Association

The preoperative evaluation is determined in light of the planned procedure (low, medium, or high risk), the planned anesthetic technique, and the postoperative disposition of the patient (outpatient or inpatient, ward bed, or intensive care

In addition, the preoperative evaluation is used to identify patient risk factors for postoperative morbidity and mortality.

If preoperative evaluation uncovers significant comorbidity or evidence of poor control of an underlying disease process, consultation with an internist or medical subspecialist may be required to facilitate the workup and direct management. In this process, communication between the surgeon and consultants is essential to define realistic goals for this optimization process and to expedite surgical management

SYSTEMS APPROACH TO PREOPERATIVE EVALUATION

Cardiovascular • Cardiovascular disease is the leading cause of death in the industrialized world, and its contribution to perioperative mortality during noncardiac surgery is significant. Of the 27 million patients undergoing surgery in the United States every year, 8 million, or nearly 30%, have significant coronary artery disease or other cardiac comorbid conditions.

One million of these patients will experience perioperative cardiac complications, with substantial morbidity, mortality, and cost. Consequently, much of the preoperative risk assessment and patient preparation centers on the cardiovascular system.

One of the first anesthesia risk categorization systems was the ASA classification. It has five stratifications: I—Normal healthy patient II—Patient with mild systemic disease III—Patient with severe systemic disease that limits activity but is not incapacitating IV—Patient who has incapacitating disease that is a constant threat to life V—Moribund patient not expected to survive 24 hours with or without an operation

There are more other systems for evaluation of cardiovascular risk such as: Goldman cardiac risk index,1977 Detsky modified multifactorial index 1986 Eagle's Criteria for Cardiac Risk Assessment, 1989 Revised Cardiac Risk Index

Once these data have been obtained, the surgeon and consultants need to weigh the benefits of surgery against the risk and determine whether any perioperative intervention will reduce the probability of a cardiac event

This intervention usually centers on coronary revascularization via coronary artery bypass or percutaneous transluminal coronary angioplasty but may include modification of the choice of anesthetic or the use of invasive intraoperative monitoring

Patients who have undergone a percutaneous coronary intervention with stenting need to have elective noncardiac procedures delayed for 4 to 6 weeks, although the delay may be shortened depending on the type of stent used (drug eluting versus non–drug eluting

The optimal timing of a surgical procedure after myocardial infarction (MI) is dependent on the duration of time since the event and assessment of the patient's risk for ischemia, either by clinical symptoms or by noninvasive study

Any patient can be evaluated as a surgical candidate after an acute MI (within 7 days of evaluation) or a recent MI (within 7-30 days of evaluation). The infarction event is considered a major clinical predictor in the context of ongoing risk for ischemia

The risk for reinfarction is generally considered low in the absence of such demonstrated risk. General recommendations are to wait 4 to 6 weeks after MI to perform elective surgery

Improvements in postoperative care have centered on decreasing the adrenergic surge associated with surgery and halting platelet activation and microvascular thrombosis

Perioperative risk for cardiovascular morbidity and mortality was decreased by 67% and 55%, respectively, in ACC/AHA-defined medium- to high-risk patients receiving β-blockers in the perioperative period versus those receiving placebo.

Although the benefit was most noticeable in the 6 months after surgery, event-free survival was significantly better in the group that received β-blockers up to 2 years after surgery.The current AHA/ACC recommendations are to start β-blocker therapy in medium- to high-risk patients undergoing major- to intermediate-risk surgery as early as possible preoperatively and titrate to a heart rate of 60 beats per minute. The choice of agent and duration of therapy are still being debated

An easy, inexpensive method to determine cardiopulmonary functional status for noncardiac surgery is the patient's ability or inability to climb two flights of stairs. Two flights of stairs is needed because it demands greater than 4 metabolic equivalents (METs).

In a review of all studies of stair climbing as preoperative assessment, prospective studies have shown it to be a good predictor of mortality associated with thoracic surgery. In major noncardiac surgery, an inability to climb two flights of stairs is an independent predictor of perioperative morbidity, but not mortality.

Pulmonary • Preoperative evaluation of pulmonary function may be necessary for either thoracic or general surgical procedures.

Whereas extremity, neurologic, and lower abdominal surgical procedures have little effect on pulmonary function and do not routinely require pulmonary function studies, thoracic and upper abdominal procedures can decrease pulmonary function and predispose to pulmonary complications

Accordingly, it is wise to consider assessment of pulmonary function for all lung resection cases, for thoracic procedures requiring single-lung ventilation, and for major abdominal and thoracic cases in patients who are older than 60 years, have significant underlying medical disease, smoke, or have overt pulmonary symptomatology

Necessary tests include forced expiratory volume in 1 second (FEV1), forced vital capacity, and the diffusing capacity of carbon monoxide

Adults with an FEV1 of less than 0.8 L/sec, or 30% of predicted, have a high risk for complications and postoperative pulmonary insufficiency. Pulmonary resections need to be planned so that the postoperative FEV1 is greater than 0.8 L/sec, or 30% of predicted. Such planning can be done with the aid of quantitative lung scans, which can indicate which segments of the lung are functional

Preoperative pulmonary assessment determines not only factors that confer increased risk but also potential targets to reduce the risk for pulmonary complications

General factors that increase risk for postoperative pulmonary complications include increasing age, lower albumin level, weight loss, and possibly obesity

Concurrent comorbid conditions such as impaired sensorium, previous stroke, congestive heart failure, acute renal failure, chronic steroid use, and blood transfusion are also associated with increased risk for postoperative pulmonary complications

Specific pulmonary risk factors include chronic obstructive pulmonary disease, smoking, preoperative sputum production, pneumonia, dyspnea, and obstructive sleep apnea.

Preoperative interventions that may decrease postoperative pulmonary complications include smoking cessation (>2 months before the planned procedure), bronchodilator therapy, antibiotic therapy for preexisting infection, and pretreatment of asthmatic patients with steroids. Perioperative strategies include the use of epidural anesthesia, vigorous pulmonary toilet and rehabilitation, and continued bronchodilator therapy.

Renal • Approximately 5% of the adult population have some degree of renal dysfunction that can affect the physiology of multiple organ systems and cause additional morbidity in the perioperative period. In fact, a preoperative creatinine level of 2.0 mg/dL or higher is an independent risk factor for cardiac complications

Identification of coexisting cardiovascular, circulatory, hematologic, and metabolic derangements secondary to renal dysfunction are the goals of preoperative evaluation in these patients

A patient with known renal insufficiency undergoes a thorough history and physical examination with particular questioning about previous MI and symptoms consistent with ischemic heart disease. The cardiovascular examination seeks to document signs of fluid overload. The patient's functional status and exercise tolerance are carefully elicited.

Diagnostic testing for patients with renal dysfunction include an electrocardiogram (ECG), serum chemistry panel, and complete blood count (CBC). If physical examination findings are suggestive of heart failure, a chest radiograph may be helpful

Urinalysis and urinary electrolyte studies are not often helpful in the setting of established renal insufficiency, although they may be diagnostic in patients with new-onset renal dysfunction.

Laboratory abnormalities are often seen in a patient with advanced renal insufficiency. Some metabolic derangements in a patient with advanced renal failure may be mild and asymptomatic and are revealed by electrolyte or blood gas analysis

Principles of Preoperative and Operative Surgery