As the number of elderly people rises, the incidence of surgery in elderly patients would become higher. This study was undertaken to examine the changes in pulmonary gas exchange that occurs with advancing age.

Arterial blood gases were analysed in 106 elderly patients over the age of 65 and 40 adult patients(control group) during breathing of room air preoperatively. Alveolar oxygen partial pressure(PAO₂), alveolar-arterial partial pressure gradient for oxygen(AaDO₂), arterial/alveolar oxygen partial pressure(a/A) ratio were calculated using PaO₂ and PaCO₂ and PAO₂ and measured the relationship between the PaO₂ and age.

PaO₂ declined as age increased significantly and the regression equation was PaO₂=103.6-0/332×age(r=0.55). There was no significant difference in PaCO₂ and PAO₂ but AaDO₂ increased and a/A ratio decreased significantly.

As the AaDO₂ and a/A ratio were changed significantly, it is necessary for monitoring of oxygenation during perioperative periods in elderly patients.