Evaluating the Effects of Hypercapnia on Recovery Time and Nausea in the Post Anesthesia Care Unit

Utah State University

Hypercapnia is often used to accelerate emergence from general anesthesia in the operating room, but little is known about the postoperative effects that may carry over to recovery in the post anesthesia care unit. We have designed two studies to address this topic, one of which has been completed. The first study monitored 22 patients undergoing eye surgery who received general anesthesia using desflurane. During emergence, half of the patients were hypercapnic and ventilated at twice their minute volume. After the desflurane was turned off the hypercapnic group open their eyes on command 4.1 +/- 1.4 min later, while the control group took 6.5 +/- 2.3 min. The hypercapnic group was also able to state their first and last name, birthdate, and current year in 10.9 +/- 5.1 min; the control group took 18.2 +/- 9.7 min. In the PACU, several subjective measures including alertness, orientation, conversant, and an Aldrete score > 8 were used to access recovery. Hypercapnic patients faired better in all categories. They also experienced less nausea and received fewer doses of antiemetic. A second study has been designed to quantify more fully the results of the first study. Pending approval of the Institutional Review Board, 44 more patients will be monitored in a similar fashion except that expired gas levels and ventilation parameters will be recorded during recovery in the PACU.