Effect of caffeine on respiratory rate, recovery time, and brain wave activity during emergence from sevoflurane anaesthesia in rats.

Objective: To determine whether caffeine affects the respiratory rate, recovery time, and brain slow-wave (theta and delta) activity during emergence from sevoflurane anaesthesia in rats.

Methods: Male Sprague-Dawley rats (n = 16) were randomly divided into two groups: control (saline) and caffeine (75 mg/kg). After tripolar electrode implantation, rats were placed in an anaesthesia induction chamber and brain electrocorticographic wave activity was recorded. Anaesthesia was induced with 4% sevoflurane (4 L/min O2) for 5 min, and once all the rats were asleep, sevoflurane concentration was reduced to 3% (4 L/min O2) for anaesthesia maintenance. Saline or caffeine was injected intraperitoneally 10 min before discontinuing anaesthesia. After sevoflurane was stopped, the rats were removed from the chamber, and the respiratory rate, tail clamp response, and the righting reflex (full emergence) were observed and noted. The frequency and amplitude of theta and delta waves (from baseline) and the frequency of theta oscillations were calculated from ECoG recordings.

Results: Caffeine administration increased the respiratory rate during sevoflurane anaesthesia; however, no significant difference vs controls was observed during full emergence. The time to tail clamp response and righting reflex, theta oscillations, and the frequency and amplitude of slow waves decreased with caffeine.

Conclusions: Acute administration of caffeine accelerates the emergence from sevoflurane anaesthesia by affecting the central nervous system. There is evidence that prolonged emergence from anaesthesia increases postoperative delirium, therefore intraoperative caffeine may reduce this risk.