219Preoperative Risk Assessment and Optimization

RECOMMENDED LABORATORIES

Recommended laboratories include: complete blood count (CBC), partial thromboplastin time (PTT), prothrombin time (PT), comprehensive metabolic panel (CMP), and liver function tests (LFTs). Other recommended studies include an EKG, a chest x-ray (CXR), and pelvic imaging as appropriate. Further workup depends on patient medical history and physical findings.

BOWEL PREPARATION

•   The administration of a preoperative bowel preparation is debatable. The pros include easy palpation of the entire colon, improved exposure, a decrease in operative time due to easier handling, and the removal of solid material from the gastrointestinal (GI) tract. The cons include more anastomotic leaks from liquid stool, more sepsis due to trauma from the prep, and nonsignificant differences in operative times or facilitated exposure.

•   There are a number of different preparations: polyethylene glycol (PEG) can be given in 4 L, magnesium citrate can be given in 300-mL bottles × 2 with or without a Dulcolax suppository, and antibiotic preparations. Antibiotic preparations include erythromycin base 1 g and neomycin 1 g; each given by mouth at 1, 2, and 10 p.m. the day before surgery. The erythromycin is given for both its antibiotic and its stimulant mechanisms of action. Another option is metronidazole 1 g and neomycin 1 g by mouth given at 1, 2, and 10 p.m. the day before surgery.

        A meta-analysis of bowel preparation and outcomes was reviewed in elective colorectal surgery for effect of type of bowel preparation on anastomotic leak, surgical site infection (SSI), and ileus. Three arms were reviewed to include: preoperative mechanical bowel preparation (MBP) and antibiotics (MBP+/ABX+), MBP alone (MBP+/ABX−), and no bowel preparation (no-prep). 8,442 patients were evaluated. 27% were given no bowel preparation, 45.3% were given a mechanical bowel preparation without antibiotics (MBP+/ABX−) and 27.5% were given mechanical bowel prep with oral antibiotics (MBP+/ABX+). Patients in the MBP+/ABX+ or MBP+/ABX− had reduced ileus [MBP+/ABX+: OR = 0.57, 95% CI: 0.48–0.68; MBP+/ABX−: OR = 0.78, 95% CI: 0.68–0.91] as well as surgical site infection [MBP+/ABX+: OR = 0.39, 95% CI: 0.32–0.48; MBP+/ABX−: OR = 0.80, 95% CI: 0.69–0.93] compared to no prep. There was also a lower association with anastomotic leak for the MBP+/ABX− group compared to no prep. On multivariate analysis, the addition of antibiotics to MBP was associated with reduced anastomotic leak rates (OR = 0.57, 95% CI: 0.35–0.94), surgical site infection (OR = 0.40, 95% CI: 0.31–0.53) and postoperative ileus (OR = 0.71, 95% CI: 0.56–0.90). Thus, MBP with oral antibiotics reduced by almost half SSI, anastomotic leak, and ileus after colorectal surgery (1).

•   It is important to rehydrate with electrolytes (Gatorade) after the preparation, and care should be taken in patients with renal, heart, or liver failure.

ASA SCORE

The American Society of Anesthesiologists Score (ASA Score) provides risk information regarding surgical patients. There are five score classifications. Gynecologic oncology patients usually fall into classes 2 or 3. Class 1 is usually healthy and young persons. Class 2 patients have mild to moderate systemic disease. Class 3 patients have severe systemic disease. Class 4 patients have severe life-threatening systemic disease, and Class 5 patients are usually moribund.

CARDIAC RISK SCORE

Cardiac risk evaluation is important because 1 of 12 patients over the age of 65 will have coronary artery disease. 30% of those undergoing major elective surgery have at least one cardiac risk factor. The Goldman multifactorial index helps to stratify patients based on their history and studies ordered (Table 4.1). The index of cardiac risk factors is listed in Table 4.1.

FUNCTIONAL STATUS

It is commonly determined by metabolic equivalents (METS). The ability to climb one flight of stairs is equal to 4 METS, and considered a decent functional status.

If a patient has a diagnosis of congestive heart failure (CHF), a recent ECHO can assist in perioperative management. Normal ejection fraction (EF) is 60% to 70%. Severe CHF is less than 40%. Care with IVF should be taken in these patients as to not fluid overload them (Table 4.2).

SUBACUTE BACTERIAL ENDOCARDITIS

Prophylaxis for subacute bacterial endocarditis (SBE) should still be remembered. There are three categories of risk that require different levels of antibiotic protection.

•   The low-risk category includes isolated secundum atrial septal defect (ASD); prior surgical repair of an ASD, ventricular septal defect (VSD), or patent ductus arteriosus (PDA) more than 6 months from surgery; a prior coronary artery bypass graft (CABG), mitral valve prolapse (MPV) without valve regurgitation; physiologic heart murmurs; prior Kawasaki disease without valve dysfunction; pacemakers and defibrillators; and prior rheumatic fever without valve dysfunction.

•   The moderate-risk category includes acquired valve dysfunctions, hypertrophic cardiomyopathy, MVP with valve regurgitation or thickened leaflets, and other congenital cardiac malformations.

•   The high-risk category includes patients with prosthetic cardiac valves, prior SBE, complex cyanotic congenital heart disease, tetralogy of Fallot, transposition of the great arteries, patients with a single ventricle, or surgically constructed systemic pulmonary shunts or conduits.

•   Treatment is directed at the moderate- and high-risk patients. Those who are moderate risk should get ampicillin 2 g IV within 30 minutes of the procedure. If they are allergic to ampicillin, they should receive vancomycin 1 g IV over 1 hour within 2 hours of starting the procedure. High-risk patients should receive ampicillin 2 g and gentamicin 1.5 mg/kg IV 30 minutes prior to surgery and again 8 hours after the surgery. If the patient is allergic to ampicillin, the patient should then receive vancomycin 1 g and gentamicin 1.5 mg/kg IV 2 hours prior to surgery and 8 hours after surgery.

COMORBIDITY INDICES

•   Charlson comorbidity index (CCI): the index accounts for the patient age and 16 conditions.

•   The CCI index predicts the 10-year mortality for patients presenting with one or more of the conditions in the model. This is an index used in decision making when a medical professional is presented with a treatment solution but needs to take into account the short- and long-term benefits of the treatment in a patient with other comorbid conditions to assess the long term risk. Each of the conditions listed is awarded a value-based point of 1, 2, 3, or 6 and combined with an age-based score. The more points given, the more likely the predicted adverse outcome. The total points are then summed. This CCI score is transformed by algorithm into a 10Y survival/mortality percentage taking into account that C is the score result obtained by summing the points.

        222Age—divided into five age groups of different risk:

             ≤40 years (0 points)

             Between 41 and 50 (1 point)

             Between 51 and 60 (2 points)

             Between 61 and 70 (3 points)

             ≥71 years (4 points)

•   Comorbidity-based score: 1, 2, 3, or 6 points depending on the mortality risk associated with each of the comorbidities.

        1 point condition—Myocardial infarction (MI), CHF, peripheral vascular disease (PVD), dementia, cerebrovascular disease, connective tissue disease, ulcer, chronic liver disease, diabetes mellitus.

        2 point condition—Hemiplegia, moderate to severe kidney disease, diabetes mellitus with end organ damage, solid tumor, leukemia, lymphoma.

        3 point condition—Moderate to severe liver disease.

        6 point condition—Malignant tumor, metastasis, AIDS (2).

•   The cumulative illness index rating scale (CIRS) was developed by Linn in 1968. Fourteen systems are evaluated and scored. The scores are then summed and can range from 0 to 56. A higher score predicts a worse outcome.

•   Scoring:

        Less than 6 and CrCL greater than 70 mL/min (GO: suitable for treatment).

        Greater than 6 and CrCL less than 70 mL/min (SLOW: suitable for reduced treatment).

        Severe comorbidities and short-life expectancy (NO: suitable for supportive care).

        Each system is rated as follows:

             1 = NONE: no impairment to that organ/system.

             2 = MILD: impairment does not interfere with normal activity; treatment may or may not be required; prognosis is excellent.

             3 = MODERATE: impairment interferes with normal activity; treatment is needed; prognosis is good.

             4 = SEVERE: impairment is disabling; treatment is urgently needed; prognosis is guarded.

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