Effect of lumbar epidural anesthesia on ventilatory response to hypercapnia in young and elderly patients

Abstract

Study Objective: To examine the influence of age on resting ventilation, arterial blood gas tensions, and the ventilatory response to hypercapnia in lumbar epidural anesthesia. Design: Clinical study using groups of young and elderly patients. Setting: Surgical operation center of a university hospital. Patients: Seven young (average age 39 years) and seven elderly (average age, 69 years) unpremeditated patients undergoing lower abdominal surgery. Interventions: Patients were administered lumbar epidural anesthesia with 10 ml of 2% lidocaine. Measurements and Main Results: Resting ventilation, arterial blood gas tensions, and ventilatory response to hypercapnia were measured before and 20 minutes after the block. Regarding the ventilatory response to hypercapnia, the mean slope of the hypercapnic response curve (change in minute ventilation (V̇E) divided by change in end-tidal partial pressure of carbon dioxide (P ET CO 2)] increased significantly following the epidural block, by 16% in the young patients. and by 23% in the elderly patients, and the mean V̇E at a P ET CO 2 of 55 mmHg (V̇E 55) also increased significantly,, by 16% in the young subjects and by 26% in the older subjects. These changes in ΔV̇E/ΔP ET CO 2 and V̇E 55 were statistically equivalent between the two age-groups. Conclusions: The effects of lumbar epidural anesthesia on resting ventilation, arterial blood gas tensions, and ventilatory response to hypercapnia were not affected by age.