Effects of hemofiltration on serum aprotinin levels in patients undergoing cardiopulmonary bypass.

OBJECTIVE: To determine the effects of hemofiltration on serum aprotinin levels during cardiopulmonary bypass (CPB) surgery. DESIGN: Prospective, randomized study. SETTING: University of Washington Medical Center, single institution. PARTICIPANTS: Patients undergoing cardiac surgery without contraindications to aprotinin administration. INTERVENTIONS: Patients were randomized to full-Hammersmith and half-Hammersmith dosing regimens of aprotinin and were further randomized to hemofiltration or no hemofiltration. MEASUREMENTS AND MAIN RESULTS: Serum aprotinin levels were studied before CPB, 60 and 120 minutes into CPB, and at the end of CPB before protamine administration. Each group experienced a decrease in serum aprotinin levels with the institution of CPB, attributable to hemodilution and redistribution of aprotinin outside of the vascular compartment. During CPB, aprotinin levels declined further, but no significant difference was observed between patients who received hemofiltration and those who did not. Hematocrit values were significantly higher at the end of CPB in the hemofiltration groups. Patients receiving half-Hammersmith dosing regimens maintained aprotinin levels throughout CPB, which have been shown to inhibit plasmin but were lower than levels previously shown to inhibit kallikrein. CONCLUSIONS: Hemofiltration during CPB did not significantly alter serum aprotinin levels in patients receiving half-Hammersmith and full-Hammersmith dosing regimens of aprotinin.

Self-reported exercise tolerance and the risk of serious perioperative complications.

BACKGROUND: Impaired exercise tolerance during formal testing is predictive of perioperative complications. However, for most patients, formal exercise testing is not indicated, and exercise tolerance is assessed by history. OBJECTIVE: To determine the relationship between self-reported exercise tolerance and serious perioperative complications. METHODS: Our study group consisted of 600 consecutive outpatients referred to a medical consultation clinic at a tertiary care medical center for preoperative evaluation before undergoing 612 major noncardiac procedures. Patients were asked to estimate the number of blocks they could walk and flights of stairs they could climb without experiencing symptomatic limitation. Patients who could not walk 4 blocks and climb 2 flights of stairs were considered to have poor exercise tolerance. All patients were evaluated for the development of 26 serious complications that occurred during hospitalization. RESULTS: Patients reporting poor exercise tolerance had more perioperative complications (20.4% vs 10.4%; P<.001). Specifically, they had more myocardial ischemia (P = .02) and more cardiovascular (P = .04) and neurologic (P = .03) events. Poor exercise tolerance predicted risk for serious complications independent of all other patient characteristics, including age (adjusted odds ratio, 1.94; 95% confidence interval, 1.19-3.17). The likelihood of a serious complication occurring was inversely related to the number blocks that could be walked (P = .006) or flights of stairs that could be climbed (P = .01). Other patient characteristics predicting serious complications in multivariable regression analysis included history of congestive heart failure, dementia, Parkinson disease, and smoking greater than or equal to 20 pack-years. CONCLUSION: Self-reported exercise tolerance can be used to predict in-hospital perioperative risk, even when using relatively simple and familiar measures.

Adverse cardiac outcomes after noncardiac surgery in patients with prior percutaneous transluminal coronary angioplasty.

UNLABELLED: In this retrospective cohort study, we compared adverse cardiac outcomes after noncardiac surgery among patients with prior percutaneous transluminal coronary angioplasty (PTCA), patients with nonrevascularized coronary artery disease (CAD), and normal controls. Inpatient hospital discharge abstracts from all nonfederal acute care hospitals in Washington State linked to death certificates were evaluated. Patients > or =45 yr old with prior PTCA who underwent noncardiac surgery from 1987 to 1993 were matched by age, sex, surgery type, and discharge year to 686 patients with CAD and to 2155 normal controls (no CAD). We compared risk for adverse cardiac outcomes (death, myocardial infarction, angina, congestive heart failure, malignant dysrhythmia, cardiogenic shock, coronary artery bypass graft, or PTCA) within 30 days. Patients with PTCA had twice the risk of adverse cardiac outcome as normal controls (odds ratio [OR] 1.98; P < 0.001), with a higher risk of angina (OR 7.84), congestive heart failure (OR 2.06), and myocardial infarction (OR 3.86) but a lower risk of death (OR 0.46; P < 0.001). Patients with PTCA had half the risk of adverse cardiac outcome as patients with CAD (OR 0.50; P < 0.001), including less risk of angina (OR 0.51) and congestive heart failure (OR 0.40; P < 0.001), but no difference in myocardial infarction (P = 0.304) or death (P = 0.436). No difference was found between 142 patients with recent PTCA (< or =90 days before noncardiac surgery) matched to patients with CAD (OR 0.90; P = 0.396). Patients revascularized by PTCA >90 days before noncardiac surgery seem to have a lower risk of poor outcome than nonrevascularized patients, although not as low as normal controls. For recent PTCA patients, the lack of difference compared with CAD patient outcomes requires a larger sample size for verification. Present findings do not lend support to a role for prophylactic PTCA to improve noncardiac surgery outcomes. This investigation did not control for CAD severity, medical management, or comorbidities. Study of these factors is needed before the clinical implications of PTCA for noncardiac surgical risk can be completely assessed. IMPLICATIONS: Hospital records showed patients with prior percutaneous transluminal coronary angioplasty were twice as likely as healthy patients to have an adverse cardiac outcome after noncardiac surgery, although their risk was reduced by half compared with patients with untreated coronary artery disease. Further study of the role of percutaneous transluminal coronary angioplasty in modulating noncardiac surgery risk is needed.

A matter of life and death: what every anesthesiologist should know about the medical, legal, and ethical aspects of declaring brain death.

Accurate criteria for death are increasingly important as it becomes more difficult for the public to distinguish between patients who are still alive from those who, through the aid of medical technology, merely look like they are alive even though they are dead. Patients and their families need to know that a clear line can be drawn between life and death, and that patients who are alive will not be unintentionally treated as though they are dead. For the public to trust the pronouncements of medical doctors as to whether a patient is dead or alive, the criteria must be unambiguous, understandable, and infallible. It is equally important to physicians that accurate, infallible criteria define death. Physicians need to know that a clear line can be drawn between life and death so that patients who are dead are not treated as though they are alive. Such criteria enable us to terminate expensive medical care to corpses. Clear criteria for death also allow us to ethically request the gift of vital organs. Clear, infallible criteria allow us to assure families and society that one living person will not be intentionally or unintentionally killed for the sake of another. The pressure of organ scarcity must not lead physicians to allow the criteria for life and death to become blurred because of the irreparable harm this would cause to the patient-physician relationship and the devastating impact it could have on organ transplantation. As the cases presented here illustrate, anesthesiologists have an important responsibility in the process of assuring that some living patients are not sacrificed to benefit others. Criteria for declaring death should be familiar to every anesthesiologist participating in organ retrieval. Before accepting the responsibility of maintaining a donor for vital organ collection, the anesthesiologist should review data supplied in the chart supporting the diagnosis of brain death and seriously question inconsistencies and inadequate testing conditions. Knowledge of brain death criteria and proper application of these criteria could have changed the course of each of the cases presented.

Angioplasty and noncardiac surgery: risks of myocardial infarction.

Prophylactic percutaneous transluminal coronary angioplasty is one revascularization strategy employed to reduce risks of cardiac complications after noncardiac surgery in certain patients. Reduced adverse cardiac event rates are at least partially offset by costs and complications of angioplasty. Patients who undergo noncardiac surgery within 90 days of coronary angioplasty may be at increased risk for postoperative cardiac complications.

Blood ionized magnesium concentrations during cardiopulmonary bypass and their correlation with other circulating cations.

BACKGROUND AND AIM: The recent introduction of new measurement technology (using ion specific electrodes) makes intraoperative evaluation of blood ionized magnesium (Mg2+, or iMg)--the bioactive fraction of circulation magnesium--possible. The goals of this study were: (1) to examine the longitudinal pattern(s) of change in blood iMg during cardiopulmonary bypass (CPB); and (2) to determine the relationship of iMg to Ca2+ (iCa), K, pH, Na, and hematocrit (Hct) during CPB. METHODS: Blood was collected serially before, during, and after CPB on 30 patients undergoing elective coronary artery bypass graft procedures and the iMg was measured with an AVL Scientific Corp., model 988-4 instrument. RESULTS: Overall, 73% of iMg results were abnormally low, 50% during CPB. Some cases had both hypo- and hyperionized magnesemic episodes. There were low iCa during CPB in 97% of cases. Using Spearman's rank order correlations and p < 0.05, iMg and K were directly correlated before, during, and after bypass, suggesting their parallel movement between tissue and blood. iMg and iCa were directly correlated before, and inversely correlated after, CPB, but unassociated during bypass. iMg and Na were inversely correlated after bypass in all cases. iMg was inversely correlated to pH and positively correlated to Hct during CPB only, and only in patients with concurrent association of iMg and iCa. CONCLUSIONS: Blood iMg depletion occurs frequently in CPB patients. iMg changes are not readily predictable. The association of intraoperative iMg depletion with postsurgical atrial fibrillation--reported to have a hypomagnesemic connection- should be investigated.

Hemodynamic and metabolic effects of aortic unclamping following emergency surgery for traumatic thoracic aortic tear in shunted and unshunted patients.

Nine cases of traumatic aortic tear treated during 1986-1987 were reviewed. Two patients had functioning Gott shunts, six patients had simple crossclamp, and one patient had a Gott shunt placed which was nonfunctional. Anesthetic management was similar in all patients. Clamp times ranged in unshunted patients from 25 to 38 minutes, and in shunted patients from 42 to 50 minutes. The crossclamp time of the patient with the nonfunctional shunt was 42 minutes. Declamping was accompanied in unshunted patients by decreases in core temperature of up to 1 degree C and acute decreases in PaO2. Marked respiratory and metabolic acidosis occurred with declamping. Respiratory acidosis resolved within 30 minutes with hyperventilation, but metabolic acidosis persisted despite bicarbonate therapy (mean = 1.2 mEq/kg) up to 6 hours after declamping. Associated elevations in serum potassium resolved as pH returned to baseline. Acid-base and electrolyte abnormalities were less marked in patients who were shunted.

Cephalosporin-induced interstitial pneumonitis.

This report describes a patient who developed dyspnea and bilateral pulmonary infiltrates following exposure to cephradine. The role of cephradine was substantiated by rechallenge.