NMS. Casos Clínicos

9

Chapter 1 ♦ Preoperative Care

◆ ◆ A previous MI increases the risk of postoperative MI. Appropriate workup includes a cardi- ology consultation and perhaps an exercise stress test to identify stress-induced ischemia. If signs of ischemia are apparent, cardiac catheterization may be necessary to determine if

coronary revascularization is required prior to surgery. Case Variation 1.2.5. The patient has diabetes.

◆ ◆ This particular patient, who will be “nothing by mouth” (NPO) after midnight, should be given IV fluids with dextrose. Patients who are taking oral hypoglycemic agents should not receive their medication the morning of surgery. Individuals with insulin-dependent diabetes mellitus (IDDM) should have their glucose levels checked the morning of surgery to ensure that they are normoglycemic. As a general rule, a slightly elevated glucose level is preferred to a reduced level. If the glucose level is greater than 250 mg/dL, most clinicians would give two thirds of the morning dose of neutral prota- mine Hagedorn (NPH) and regular insulin. If the glucose level is less than 250 mg/dL, you could administer one-half of the morning dose. Case Variation 1.2.6. The patient’s hematocrit is 34%, and his other laboratory tests are normal. ◆ ◆ The patient is anemic, and the reason for the anemia must be determined. The surgery should possibly be postponed. A common cause of anemia is colorectal cancer, but other causes should be investigated if the workup for gastrointestinal (GI) blood loss is negative. Case Variation 1.2.7. The patient’s hematocrit is 55%. ◆ ◆ This result suggests that the patient has either hypovolemia or polycythemia due to some other condition. If dehydration is present, surgery should be delayed until the patient is well hydrated. Physical signs of dehydration include poor skin turgor, tachycardia, and dry mouth. ◆ ◆ Important but less common causes of polycythemia such as polycythemia vera, chronic obstructive pulmonary disease (COPD), and erythropoietin-secreting tumors (e.g., re- nal cell carcinoma, hepatocellular carcinoma) should be diagnosed and treated prior to elective surgery. Regardless of the cause, the polycythemia should be evaluated, and the risk assessed prior to surgery. If patients with polycythe- mia vera need surgery, the operative risk for thrombotic complications is increased unless the hematocrit is normalized; a combination of hydration and phlebotomy can be used. Case Variation 1.2.8. The patient is obese (>100lb overweight) and reports becoming winded easily when climbing stairs. ◆ ◆ Obese patients have a higher incidence of hypertension and cardiovas- cular disease. Severe cases result in hypoventilation, hypercapnia, and pulmonary hypertension. These individuals are also at increased risk for adult-onset diabetes mellitus and deep venous thrombosis (DVT). A com- plete medical evaluation is necessary, including an evaluation of pulmonary status prior to surgery and optimization of functional capacity with bronchodilators and antibiotics as appropriate. At a minimum, this will involve arterial blood gases (ABGs), as well as pulmonary function studies if ABGs are abnormal. Because the hernia repair is elec- tive, postponing the surgery may be an option if the patient is willing to participate in a weight loss program. Otherwise aggressive postoperative pulmonary care may be used to attempt to avoid atelectasis. SAMPLE