NMS. Casos Clínicos

14

Part I ♦ Foundations

Case 1.6 Cardiac and Neurologic Risk Associated with Surgery for Peripheral Vascular Disease A 74-year-old presents with a recent onset of rest pain in the right foot. The patient has had non–insulin-dependent diabetes mellitus (NIDDM) for the past 8 years, smokes two packs of cigarettes per day, and has a history of mild hypertension that is well controlled with an angiotensin-converting enzyme (ACE) inhibitor. On physical examination, obvious ischemia of the right foot is evident, with absent popliteal and pedal pulses, dependent rubor, loss of lower leg hair, and shiny skin. The ankle–brachial index (ABI) is 0.4, indicating severe ischemia of the leg. You recommend a revascularization procedure to salvage the leg. An angio- gram indicates that a bypass from the femoral artery to the distal tibial vessels is necessary for adequate revascularization. To proceed safely, you should evaluate the medical risk.

AHA Approach to Evaluating Cardiac Risk for Noncardiac Surgery A general approach to evaluating cardiac risk for noncardiac surgery has been formulated by the AHA (Fig. 1-1). This algorithm can be used in a stepwise man- ner as follows: 1. Step 1: If a patient needs an emergency noncardiac procedure, proceed with the procedure and take steps to minimize cardiac stress during the intra- and postoperative period. This is primarily by careful heart rate control and avoid- ing hypoxia, electrolyte abnormalities, hypotension, and wide fluid shifts. 2. Step 2: If not an emergency and thus is an elective procedure, evaluate for active cardiac conditions, as seen in Table 1-1. If present, evaluate and treat them by AHA guidelines before proceeding with surgery. 3. Step 3: For an elective procedure and no active cardiac conditions, look at the surgical procedure planned, as shown in Table 1-2. If a low-risk surgical procedure is planned, then proceed with the surgery. 4. Step 4: If the surgical procedure is higher risk, determine the functional status of the patient. For patients who are physically active, this can be estimated using Table 1-3. If the estimate is at or above 4 METs, then proceed with surgery. If physical activity is limited for a variety of reasons, such as with a leg amputation or toe infection, or the METs estimate is below 4, then a more complicated series of steps is recommended based on the number of risk factors present (see Table 1-6). 5. Step 5: Is generally performed if it will change the management of the pa- tient. Cardiac functional assessment helps to establish risk based on cardiac perfusion under conditions of increased oxygen demand as seen in a cardiac stress test. SAMPLE