Comparison of Hemodynamic and Oxygen Availability after Apnea between a Case with Anesthesia and a Case without Anesthesia

Cheun, Jae Kyu; Jang, Young Ho; Bae, Jung In; Song, Dae Kyu

Abstract

BACKGROUND: Acutely induced hypoxia causes an increase in the mean arterial pressure, cardiac output and oxygen consumption. However, comparisons of hemodynamic changes and oxygen consumption between subjects with and without anesthesia are rare. The purpose of this study was to examine and compare the hemodynamic changes and oxygen availability after acute apnea between the dogs with and without anesthesia.
METHODS
Apnea was induced to 19 healthy mongrel dogs. Group 1 (N=10) constituted dogs with anesthesia and group 2 (N=9) constituted dogs without anesthesia. Hemodynamic data and oxygen levels were rapidly measured with 1 minute intervals.
RESULTS
The survival time of group 1 was longer than that of group 2. The mean arterial pressure increased in group 1. Although the cardiac outputs in both groups increased at the same time course in early phase of apnea, the preload values increased more rapidly in group 1. Systemic vascular resistance decreased at 2 and 3 minutes of apnea in group 1 but not in group 2. The oxygen extraction ratio increased significantly at 4 and 5 minutes of apnea in group 2.
CONCLUSION
In this study the dogs with anesthesia had a prolonged survival time compared to the dogs without anesthesia. Most hemodynamic values did not differ significantly between the two groups, except for an increased mean arterial pressure and decreased systemic vascular resistance in the dogs with anesthesia. It was suggested that the cause of early death in the dogs without anesthesia was decreased oxygen delivery.