Christopher J. O'Connor

Aspirin does not increase allogeneic blood transfusion in reoperative coronary artery surgery.

While preoperative aspirin (ASA) therapy does not increase allogeneic transfusion in elective primary coronary artery bypass grafting (CABG) operations, the impact of ASA consumption on transfusion in cardiac operations with greater risk of bleeding has not been investigated.We examined the influence of ASA consumption on mediastinal drainage and allogeneic transfusion in 317 patients undergoing reoperative CABG surgery. Patients receiving ASA or ASA containing medications within 7 days preoperatively (n = 215) had similar perioperative characteristics but were older and had smaller red cell volumes than control patients not receiving ASA (n = 102). All patients received aminocaproic acid, but autotransfusion of mediastinal blood or platelet rich plasma, aprotinin, or desmopressin were not used. No significant differences were observed between ASA and control groups with respect to postoperative hematocrit, mediastinal drainage, frequency of reexploration for excessive bleeding, amount of allogeneic packed red blood cell, fresh frozen plasma, platelet concentrate or cryoprecipitate transfusion, or the fraction of patients receiving any allogeneic blood product. There was no difference in mediastinal drainage when stratified by timing of most recent ASA ingestion. Multiple linear regression identified duration of cardiopulmonary bypass (CPB), internal mammary artery harvesting, chronic preoperative steroid therapy and use of an intraaortic balloon pump (IABP) as significant predictors of mediastinal drainage. Logistic regression demonstrated that female gender, prolonged duration of CPB, advanced age, use of IABP, and a negative history of smoking were significant independent predictors of blood product transfusion. There was no significant interaction of preoperative heparin therapy with ASA on transfusion demonstrated by univariate or multivariate analyses. These results indicate that preoperative ASA ingestion is not an important determinant of mediastinal drainage or allogeneic transfusion, even after repeat CABG operations, and that surgical and patient characteristics are more important predictors of these outcomes. (Anesth Analg 1996;83:1178-84)

The impact of renal dysfunction on aprotinin pharmacokinetics during cardiopulmonary bypass

UNLABELLED Aprotinin is a serine protease inhibitor that undergoes metabolism in the kidney. Because elimination is almost entirely renal, the clearance of aprotinin may be reduced in patients with renal insufficiency. Unfortunately, there are no data regarding aprotinin pharmacokinetics in cardiac surgical patients with renal insufficiency or end-stage renal disease (ESRD) undergoing cardiopulmonary bypass (CPB). We, therefore, determined the clearance (ApCl) and elimination half-life (T1/2) of aprotinin in 26 cardiac surgical patients with normal and abnormal renal function (creatinine clearance [CrCl] 0-122 mL/min) undergoing CPB. Subjects were given a 2 million kallikrein inhibiting unit (KIU) initial dose of aprotinin, followed by a 0.25 million KIU/h infusion. No aprotinin was added to the pump prime. Plasma aprotinin concentrations were sampled at 30 min after completion of the loading dose, 30 and 60 min after the onset of CPB, at the end of CPB, and at 8, 24, and 32 h after completion of the loading dose. ApCl was directly related and the elimination T1/2 inversely related to CrCl (r = 0.75 and 0.42, respectively). In patients with a CrCl >50 mL/min, the T1/2 and ApCl were 7.8 h and 53 mL/min, respectively, compared with 19.9 h and 25 mL/min (P < 0.05, P < 0.002, respectively) for patients with ESRD. In conclusion, ApCl is reduced, and T1/2 is prolonged in patients with renal insufficiency or ESRD undergoing CPB. Dosing modifications may be necessary for patients with abnormal renal function undergoing cardiac surgery. IMPLICATIONS Because aprotinin is metabolized and eliminated in the kidney, its clearance may be reduced in patients with renal insufficiency. Our data suggest that aprotinin clearance is reduced, and aprotinin half-lives are prolonged in patients with renal insufficiency undergoing CPB. Dosing modification may therefore be indicated when aprotinin is administered to these patients for cardiac surgery.

Anesthesia and the Hepatobiliary System

• All volatile anesthetics decrease hepatic blood flow, but desflurane and sevoflurane have the least significant effect on total hepatic blood flow and hepatic oxygen delivery, whereas halothane induces the most profound reductions in hepatic blood flow. • Advanced liver disease may impair the elimination, prolong the half-life, and potentiate the clinical effects of several drugs, including morphine, meperidine, alfentanil, vecuronium, rocuronium, mivacurium, benzodiazepines, and dexmedetomidine. These drugs should be used cautiously in patients with cirrhosis or end-stage liver disease from any cause, and their dosage and administration should be adjusted accordingly. • Abnormal liver enzyme test results may be seen in up to 4% of normal individuals and up to 36% of psychiatric patients, although the prevalence of clinically significant hepatic dysfunction in these individuals is less than 1%, thus suggesting that further costly preoperative testing is unnecessary in asymptomatic patients. • Patients with asymptomatic elevations in serum transaminase levels (less than two times normal values) may undergo surgery with minimal impact on perioperative outcome. • Retrospective data suggest that patients with acute hepatitis from any cause are at increased risk for hepatic failure and death after elective surgery. Thus, elective surgery should be delayed in these individuals until resolution of acute hepatocellular dysfunction can be confirmed. • Asymptomatic patients with any form of chronic hepatitis should be carefully assessed before elective surgery, and meticulous care should be taken to maintain hepatic perfusion in the perioperative period and to avoid any hepatotoxic drugs or significant hypotension that could precipitate liver failure or hepatic encephalopathy. • Based on large retrospective studies, patients with cirrhosis who are undergoing abdominal surgery, especially those in Child-Turcotte-Pugh (CTP) class C, appear to have an increased risk of perioperative death. Elective surgery in these individuals should be avoided, if possible, in favor of less invasive procedures. • Postoperative jaundice may occur as a result of intraoperative hepatobiliary injury, anesthetic-induced hepatotoxicity, severe hepatic hypoperfusion (e.g., cardiogenic or hypovolemic shock), and a variety of medications. • Patients with the most advanced forms of liver disease (e.g., CTP class B or C cirrhosis) should receive management designed to maximize hepatic perfusion and hepatic oxygen delivery and to prevent and treat the complications of hepatic encephalopathy, cerebral edema, coagulopathy, hemorrhage, and portal hypertension.

The Effect of Esmolol Pretreatment on the Incidence of Regional Wall Motion Abnormalities During Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is associated with dramatic increases in arterial blood pressure and heart rate (HR) that may precipitate new left ventricular regional wall motion abnormalities (RWMAs) suggestive of myocardial ischemia.The purpose of this study was to investigate the effect of pretreatment with esmolol on the incidence of RWMAs after ECT. Thirteen patients served as their own controls and, in a random fashion, received a standard succinylcholine/methohexital anesthetic for one of two ECT sessions, and an identical anesthetic with esmolol 1 mg/kg for their other ECT session. Systolic (SBP), diastolic (DBP), mean arterial pressures (MAP) and HR were recorded after drug administration and before ECT and at 1-, 2-, 4-, 5-, 10-, and 15-min intervals after ECT. Echocardiograms were obtained at baseline, after drug administration, 1 min after ECT, and at recovery 15 min later. All patients had significant increases in SBP, DBP, and MAP at 1, 2, and 4 min after ECT versus baseline, whereas HR was significantly faster at all times in the control sessions. HR was significantly slower after anesthetic induction until 2 min after ECT in the esmolol versus the control group (P < 0.05). New RWMAs were seen in only 1 of 26 (4%) ECT sessions, despite the presence of baseline RWMAs in 31% of the patients. We conclude that contrary to previously reported data, new RWMAs after ECT are uncommon. Consequently, this study was unable to demonstrate any beneficial effect of pretreatment with esmolol on the incidence of ECT-induced RWMAs. (Anesth Analg 1996;82:143-7)

The Intraoperative Management of Patients with Pericardial Tamponade

The anesthetic management of patients with pericardial tamponade is challenging, as they present with not only the cardiovascular compromise that defines pericardial tamponade, but often have comorbid conditions that increase the complexity of their management. This review describes the pathophysiology, etiology, clinical presentation, and anesthetic management of patients with pericardial tamponade, with an emphasis on the intraoperative period and the management of pericardial window procedures, the most common clinical scenario where anesthesiologists will encounter pericardial tamponade.

Severe myxedema after cardiopulmonary bypass.

IMPLICATIONS We report a case illustrating the serious perioperative consequences that can potentially result from failure to provide adequate thyroid hormone therapy for severe hypothyroidism before cardiac surgery.

Chest trauma: The role of transesophageal echocardiography

Aortic and cardiac injury is commonly seen with severe chest trauma and contributes to the morbidity and mortality of automobile accidents. Transesophageal echocardiography is emerging as an important diagnostic tool for the evaluation of cardiovascular injury in the setting of acute chest trauma, and anesthesiologists should be familiar with the echocardiographic features of these traumatic lesions.

PERIOPERATIVE HYPERTENSION AND OUTCOME

Hypertension is one of the most common chronic illnesses encountered in the perioperative period. Affecting approximately 20% of the U.S. population, hypertension is a causative factor in the development of many other diseases that ultimately require surgical intervention. The incidence of perioperative hypertension varies from 3% to 75% and depends on both the precise criteria used to define it and the surgical population studied.32 Using a blood pressure greater than 160/90 mm Hg to define hypertension, Goldman and Caldera7 reported that 57%, 29%, and 8% of patients undergoing abdominal aortic surgery, peripheral vascular surgery, or intraperitoneal or intrathoracic surgery, respectively, were hypertensive. Hypertension was seen in 4% of all other procedures. Goldmans definition of hypertension has since been used in many investigations of perioperative hypertension and has become one of many accepted definitions. Because of the variability that exists in defining perioperative hypertension, consistent parameters cannot always be cited when comparing studies. To clarify what encompasses perioperative hypertension, the authors have defined perioperative hypertension as that manifesting as chronic hypertension (controlled or uncontrolled) or as similar elevations in blood pressure occurring in the preoperative, intraoperative, or postoperative period, whether or not they occur in patients with preexisting hypertension.

An Unusual Cardiac Mass Shown By Intraoperative Transesophageal Echocardiography

A 49-YEAR-OLD man with a history of coronary artery disease (CAD) and three prior myocardial infarctions (MIs) was admitted to an outside hospital with the recent onset of unstable angina. A coronary anglogram demonstrated an 80% mid-left anterior descending artery (LAD) occlusion, an 80% first diagonal occlusion, a subtotal circumflex occlusion, and moderate right coronary artery (RCA) disease. The left ventriculogram showed regional left ventrlcular dysfunction, and the electrocardiogram demonstrated an old inferior wall MI and new lateral wall ischemia. After an acute MI was ruled out, the patient was treated with intravenous heparin and nitroglycerin and transferred to this institution for surgical revascularization. Anesthetic induction was uneventful and baseline hemodynamic parameters were within normal limits. Routine biplane transesophageal echocardiography (TEE) exammation after induction showed an unusual structure m the four-chamber long-axis view (Fig 1). Color Doppler imaging showed minimal to no flow within this structure. What is this lesion?