Intraoperative urinary output does not predict postoperative renal function in patients undergoing abdominal aortic revascularization.

To determine whether intraoperative urinary output was predictive of postoperative renal function, mean urinary output and lowest hourly urinary output were measured in 137 patients during operation for aortic reconstruction. Pulmonary capillary wedge pressure was kept within normal limits. If urinary output was less than 0.125 ml X kg-1 X hr-1, patients were given crystalloid solution, mannitol, furosemide (Lasix), or nothing. For each patient, serum creatinine and blood urea nitrogen (BUN) levels were assayed on postoperative days 1, 3, and 7. There was no significant correlation between intraoperative mean urinary output or lowest hourly urinary output and change from preoperative to postoperative levels of creatinine or BUN. Twenty-one patients had postoperative renal insufficiency; of these, 17 had had renal disease before operation. In these patients as well; mean urinary output and the lowest hourly urinary output did not correlate with change in BUN or creatinine levels. The position of the aortic cross-clamp did not affect these correlations. Therefore, intraoperative urinary output was not predictive of postoperative renal insufficiency in patients undergoing aortic reconstruction.

Monitoring with two-dimensional transesophageal echocardiography. Comparison of myocardial function in patients undergoing supraceliac, suprarenal-infraceliac, or infrarenal aortic occlusion.

When the aorta must be temporarily occluded at the suprarenal or supraceliac levels during surgery, the resulting large increase in afterload may make the myocardium ischemic, even though systemic and pulmonary artery pressures and cardiac output are maintained at normal levels. These traditional indices of myocardial well-being do not appear to be sufficiently sensitive, since cardiac complications are still the most frequent cause of perioperative death and morbidity after aortic reconstruction. To evaluate two-dimensional transesophageal echocardiography as a monitor of myocardial well-being, we studied 24 American Society of Anesthesiologists physical status class III or IV adult patients who were undergoing aortic reconstruction and occlusion at the supraceliac (n = 12), suprarenal-infraceliac (n = 6), or infrarenal (n = 6) level. In addition to traditional monitors, we used a gastroscope tipped with a special 3.5 MHz two-dimensional echocardiographic transducer (Diasonics) that was placed in the esophagus to give a cross-sectional view of the left ventricle through the base of the papillary muscles. The hemodynamic effects of clamping the aorta were managed by administration of vasodilating drugs, anesthetics, and fluids to keep systemic and pulmonary arterial pressures normal. Occlusion at the supraceliac level caused major increases in left ventricular end-systolic and end-diastolic areas, decreases in ejection fraction, and frequent wall motion abnormalities; these changes were not detected by conventional monitoring devices. Occlusion at the suprarenal-infraceliac level caused similar but smaller changes, and occlusion at the infrarenal level caused only minimal cardiovascular effects. We conclude that the two-dimensional transesophageal echocardiogram offers promise as an intraoperative monitoring device.

The effect of alpha-adrenergic blockade on cardiac performance and tissue oxygen delivery during excision of pheochromocytoma.

To establish criteria for administration of the optimal dose of alpha-adrenergic receptor blocking drugs, we studied cardiac performance and tissue oxygen tension in three patients who underwent excision of pheochromocytoma. Subcutaneous oxygen tension was measured by the method of Niinikoski and Hunt. Cardiac function was assessed by thermodilution cardiac output, systemic and pulmonary arterial blood pressures, and continuous two-dimensional transesophageal echocardiography of a cross section of the left ventricle at the level of the papillary muscles. Despite large changes in cardiac output and systemic, pulmonary, and wedge pressures, intraoperative tissue oxygen tensions and ejection fractions remained normal (even at times of peak catecholamine excretion and very abnormal wedge pressures). Studies of healthy animals that received no alpha-adrenergic receptor blocking drugs showed major decrements of tissue oxygen in response to modest doses of epinephrine. We conclude that progressive administration of alpha-adrenergic receptor blocking drugs does not absolutely protect the patient from major changes in blood pressure during operation for pheochromocytoma, but that cardiac performance and oxygen supply to the tissues are unimpaired.