Preoperative Preparation of the Patient for Colon and Rectal Surgery

Introduction

The goal of preoperative assessment and preparation for a patient undergoing colon and rectal surgery is to minimize the risk of perioperative complications and optimize outcomes. Advancing age, obesity, and comorbidities such as cardiopulmonary disease and malnutrition are all factors that contribute to perioperative risk and are becoming more prevalent. Although these factors do not preclude surgery, they complicate preoperative assessment and increase the risk of postsurgical complications. Understanding the impact of these conditions on outcomes and tailoring interventions that optimize a patient’s health status prior to surgery are important steps in preparing for surgery. This chapter will cover common concerns critical to the preparation of a patient for colon and rectal surgery.

Risk Assessment

Many screening instruments have been designed to assist surgeons in classifying a patient’s overall surgical risk. The following three tools are commonly used in colon and rectal surgery: American Society of Anesthesiologists (ASA) grade, Physiologic and Operative Severity Score for enumeration of Mortality and Morbidity (POSSUM), and the Association of Coloproctology of Great Britain and Ireland (ACPGBI) tool. Each tool has proven benefits and limitations.

The ASA Physical Status Classification, which was introduced in 1941 by Saklad, is now commonly referred to as the ASA grade. This simple stratification was intended to describe a patient’s preoperative condition rather than estimate operative risk. The five grades ( Table 34-1 ) have been shown to correlate with intraoperative factors (such as blood loss) and outcomes, such as duration of intensive care unit stay, necessity of postoperative ventilation, and perioperative mortality and morbidity. Although it is simple to use, the ASA grade is limited by its subjectivity.

TABLE 34-1

American Society of Anesthesiologists Physical Status Classification

ASA Grade	Definition
I	Normal, healthy individual
II	Mild systemic disease that does not limit activity
III	Severe systemic disease that limits activity but is not incapacitating
IV	Incapacitating systemic disease that is constantly life threatening
V	Moribund; not expected to survive 24 hr with or without surgery
E	Emergency

ASA, American Society of Anesthesiologists.

POSSUM was introduced by Copeland in 1991 as a format for auditing quality of surgical care. This scoring system assigns numeric weights to 12 physiologic parameters and 6 operative factors ( Table 34-2 ); the total score predicts morbidity and mortality. To reduce overestimates in mortality and to address the risk specific to patients undergoing colon and rectal surgery, the instrument was modified as the Colorectal POSSUM (CR-POSSUM). In addition to the eight original parameters (age, cardiac signs, pulse, systolic blood pressure, urea concentration, operative severity, peritoneal soiling, and malignancy), assessment of the operative urgency and preoperative hemoglobin are also included ( Table 34-3 ). CR-POSSUM has been shown to accurately predict mortality after colon and rectal surgery, although it continues to overestimate it, especially with laparoscopic procedures and in patients with colon cancer.

TABLE 34-2

Physiologic and Operative Severity Score for Enumeration of Mortality and Morbidity (POSSUM) Variables to Predict Morbidity and Mortality

Physiologic Parameters	Operative Parameters
Age (yr) Cardiac symptoms Respiratory symptoms Pulse (beats/min) Systolic blood pressure (mm Hg) Glasgow Coma Scale score Hemoglobin (g/dL) White blood cell count Urea concentration (mmol/L) Sodium level (mmol/L) Potassium level (mmol/L) Electrocardiogram	Operative severity Multiple procedures Total blood loss (mL) Peritoneal soiling Presence of malignancy Mode of surgery

TABLE 34-3

Colorectal Physiologic and Operative Severity Score for Enumeration of Mortality and Morbidity (CR-POSSUM) Variables and Scoring to Estimate Mortality

Variable	Score
Physiologic
Age	1	2	3	4	8
Cardiac failure	None/mild	Moderate	Severe
Systolic BP (mm Hg)	100-170	90-99 or >170	<90
	≤60		61-70	71-80	>80
Pulse (beats/min)	40-100	101-120	<40 or >120
Urea (mmol/L)	≤10	10.1-15	>15
Hemoglobin (g/dL)	13-16	10-12.9 or 16.1-18	<10 or >18
Operative
Operative severity	Minor		Intermediate	Major	Major +
Peritoneal soiling	None/serous	Local pus	Free pus or feces
Operative urgency	Elective		Urgent		Emergent
Cancer staging	None or Duke A/B	Duke C	Duke D

Equation used to calculate risk (R) of mortality:

Log[R/(R − 1)] = −9.167 + (0.33 × Physiologic score) + (0.3 × Operative Score)

BP, Blood pressure; Duke, Duke Activity Status Index.

In a further effort to address surgical risk in patients with colon and rectal cancer, the ACPGBI released its own scoring system in 2010 as an online tool. The ACPGBI, which is the simplest of the three tools, uses five variables: age, ASA grade, Duke’s Stage, surgical urgency, and operative procedure (formerly cancer resection status). It has been shown to be a more accurate predictor of surgical mortality than both CR-POSSUM and ASA grade, especially for elective cases, with consistent performance for elderly patients and emergency cases as well.

In 2013, the American College of Surgeons (ACS) developed the ACS NSQIP Surgical Risk Calculator. This online decision support tool ( http://riskcalculator.facs.org/ ) utilizes 21 patient predictors to estimate the risk of 9 potential complications occurring within 30 days after surgery. These complications include death, cardiac events, pulmonary events, renal failure, surgical site and deep organ space infections, urinary tract infection, and thromboembolic complications, including pulmonary embolism (PE) and stroke. Not only are patient factors entered into the equation, but the magnitude of the surgery is included in the algorithm. The tool also provides a predicted length of stay based on specific Current Procedural Terminology (CPT) codes, allowing both the surgeon and the patient to have realistic expectations of the planned surgery.

Although no single tool can substitute for sound clinical acumen, these tools can help the surgeon and the patient manage expectations and potentially improve outcomes.

Cardiovascular Assessment and Preoperative Management

Induction of anesthesia and the patient’s autonomic response to surgery can cause significant cardiac stress resulting in arrhythmias, ischemia, or infarction in the intra- and postoperative periods. Consequently, cardiovascular comorbidity is an important contributor to perioperative morbidity and mortality. Estimates of cardiac complication rates are between 1% and 5% for colorectal abdominal operations, equating to an intermediate cardiac risk. This risk is higher in elderly persons. As the number of elderly patients presenting for colon and rectal surgery continues to rise, understanding how to assess cardiac fitness and minimize perioperative risk is important. To this end, The American College of Cardiology (ACC) and the American Heart Association (AHA) have established practice guidelines for preoperative cardiac assessment in noncardiac surgery.

The goal of the preoperative cardiac assessment is to evaluate the patient’s current medical status and “provide a clinical risk profile” that “can [be] used to make treatment decisions that influence the patients’ short and long term outcomes.” The Revised Cardiac Risk Index is a scoring system to help guide this assessment. The index awards one point each to six factors: high-risk surgery, history of ischemic heart disease, history of congestive heart failure, history of cerebrovascular disease, insulin-dependent diabetes, and renal insufficiency (creatinine >2.0 mg/dL). The total number of points correlates to predictive rates of major cardiac complications ( Table 34-4 ).

TABLE 34-4

Revised Cardiac Risk Index and Associated Cardiac Risk Estimates

Risk Factors	No. of Risk Factors	Predicted Rate of Cardiac Complication, %
High-risk surgery	1	0.5
Ischemic heart disease	2	1.3
Congestive heart failure	3	3.6
Cerebrovascular disease	≥4	9.1
Insulin-dependent diabetes	1	0.9
Creatinine >2.0	1	0.9

During this assessment, it is important to differentiate clinical risk factors from active disease. Active disease is defined as unstable coronary syndrome, including unstable or severe angina or recent (<1 month) myocardial infarction, decompensated heart failure, significant arrhythmias, and severe valvular disease. These conditions mandate further investigation prior to surgery. If an intervention is required, elective surgery should be postponed up to 4 to 6 weeks in patients with acute myocardial infarction or stent placement. If placement of a cardiac stent is required, use of a drug-eluting stent should be avoided, because these stents have shown higher rates of thrombosis when antiplatelet therapy is withheld within 1 year of placement.

Functional capacity is another important aspect of cardiac risk assessment. The Duke Activity Status Index quantifies common daily activities into metabolic equivalents (METs), with scale ranges from 1 (eat or dress) to greater than 10 (strenuous activity). Surgeons can use METs as units of measure to identify cardiac disease or cardiac intolerance. For example, the inability to perform a minimum of 4 METs (e.g., light housework, such as dusting and washing dishes) should prompt additional cardiovascular consultation.

Although most pertinent information can be obtained through a thorough history and physical examination, other tests, including an electrocardiogram, echocardiogram, or noninvasive stress test, can be important. Box 34-1 details recommendations from the ACC/AHA practice guidelines for cardiac diagnostic tests.

BOX 34-1

Electrocardiogram

Indicated in:

•

Patients with known CAD, PAD, or cerebrovascular disease who will undergo intermediate-risk surgery ^†

† Intermediate risk surgery (1%-5% cardiac risk): intra-abdominal procedures, carotid, head and neck, orthopedic, prostate.
•

Patients with ≥1 clinical risk factor

Not indicated in:

•

Asymptomatic patients undergoing low-risk surgery ^∗

∗ Low-risk surgery (<1% cardiac risk): endoscopy, ophthalmologic procedure, breast.

Assess LV Function

Indicated in:

•

Patients with dyspnea of unknown origin
•

Patients with heart failure who have not had a recent (<12 mo) echocardiogram AND who have a change in clinical status

Noninvasive Stress Testing

Indicated in:

•

Patients with active cardiac conditions
•

Patients with >1 clinical risk factor and poor functional capacity who will undergo intermediate-risk surgery ^†

Not indicated in:
•

Patients with no risk factors
•

Patients undergoing low-risk surgery