Effects of Inspired Gas Composition during Anesthesia on Postoperative Arterial Oxygenation in Elderly Patients

Baek, Chong Wha; Park, Jung Won; Jung, Yong Hun

Abstract

BACKGROUND
Atelectasis is an important cause of impaired gas exchange during the perioperative period. The administration of 100% oxygen, even for brief periods, is associated with pulmonary absorption atelectasis, and the addition of N2O to the inspired gas may promote atelectasis. The aim of this study was to evaluate the effect of inspired gas composition on postoperative arterial oxygenation in elderly patients.
METHODS
Twenty-six female patients with healthy hearts and lungs, and aged 60 yrs, who were scheduled for laparoscopic cholecystectomy, were divided into two groups. All patients received propofol-fentanyl anesthesia. In the N2O group, patients were ventilated with 100% oxygen during induction, 40% oxygen in N2O during mataintenance, and 100% oxygen during emergence. In the air group, patients received 60% oxygen in air during induction, 40% oxygen in air during maintenance, and 60% oxygen in air during emergence. Arterial blood gases were obtained to evaluate arterial oxygenation by analyzing PaO2 and alveolar arterial oxygen tension differences (AaDO2).
RESULTS
In both groups, postoperative PaO2 was lower and AaDO2 higher than preoperative values (P < 0.05), but there were no differences between the two groups.
CONCLUSIONS
We conclude that absorption atelectasis during anesthesia is not the main cause of postoperative arterial oxygenation impairment in eldery patients, and that any effect of the inspired gas is likely to be of limited clinical significance.