Mild hypercapnia with hyperventilation attenuates recovery from anesthesia in elderly patients

Mild hypercapnia with hyperventilation has been reported to significantly decrease recovery time from inhaled anesthesia in young and middle-aged patients. However, its efficacy has not yet been clarified in elderly patients, although delayed emergence can deteriorate their quality of recovery.

We enrolled 30 elderly patients (≥65 years) and 30 middle-aged patients (45-64 years) who were scheduled for ophthalmic surgery and allocated them to the control or the device group. Anesthesia was maintained with 1.5% sevoflurane. Mild hypercapnic hyperventilation was induced by the ANEclear anesthesia recovery device. The primary outcome was the time from vaporizer shut-off to initial response (eye or mouth opening, nodding, or grasping hand) in elderly patients. The secondary outcomes were the time to extubation and leaving the operating room (OR), the time to reach 50% of the difference between BIS at extubation and vaporizer shut-off (BIS ET50), and interaction between the recovery measures and patient age.

The ANEclear significantly reduced the time to initial response, extubation, leaving the OR, and BIS ET50 in both age groups: their means and 95% CI of the ratio of two means (Mean(ANEclear)/Mean(control)) were 0.576 (0.500, 0.660), 0.595 (0.523, 0.673), 0.713 (0.622, 0.812), and 0.547 (0.444, 0.663), respectively, in the elderly group, and 0.717 (0.591, 0.849), 0.723 (0.609, 0.842), 0.855 (0.736, 0.982), and 0.631 (0.463, 0.813), respectively, in the middle-aged group. The recovery measures were shortened equally in both age groups: P values for the interaction were 0.060679, 0.062534, 0.069215, and 0.420061, respectively.

Recovery time was significantly decreased by the ANEclear in the elderly group. This reduction was comparable to the time for middle-aged patients.