Aortic Blood Flow Measurement

Abstract

Aortic blood flow (ABF) was measured with a specially designed ultrasonic probe (diameter 6.8 mm, length 50 cm) introduced into the esophagus. The aortic diameter was measured using an A-scan system. Mean blood velocity was obtained with a continuous-wave Doppler velocimeter. The ABF was calculated from these two parameters. The precision of the measurement was assured by the external orientation of the transducers enclosed in a latex water-inflated balloon. A reproducibility study was conducted by a double-blind method. The differences between different operators were less than 5 % in a series of 11 patients. In over 21 patients, 300 comparative measurements with thermodilution showed a correlation coefficient of 0.97. Using this technique the hemodynamic effects of ornithine-vasopressin and etilefrin were compared in two groups of 6 female patients under general anesthesia, during local injection, for conization of the uterine cervix. After injection, systolic blood pressure rose 31 and 29 % (p <0.01) in the ornithine-vasopressin and etilefrin groups, respectively. Heart rate decreased 16 and 10% respectively. ABF decreased 43% under ornithine-vasopressin (p < 0.001), but increased 12% (NS) in the etilefrin group. The difference between the two groups was significant (p < 0.001). The stroke volume into descending aorta fell 40% in the ornithine-vasopressin groups (p < 0.01), but under etilefrin it increased 13% (NS). There was a significant difference between the two groups (p < 0.001). Hemodynamic changes appear to be less pronounced in the etilefrin group. The preservation of ABF and stroke volume under etilefrin should be an element of a better cardiovascular protection and a better tissular perfusion. Only the use of ABF measurements shows hemodynamic differences between the two groups.