Research led by Robert Fong, MD, PhD, with scientists from the Departments of Anesthesia and Critical Care and Neurobiology, University of Chicago; the Department of Anesthesia, Guangzhou Medical University, Guangzhou, China; and the Cancer Center and College of Medicine, University of Illinois at Chicago sought to test the hypothesis that patients given caffeine were able to regain consciousness more quickly than individuals who were not.

When describing the importance of their work, the researchers noted, “There are currently no drugs clinically available to reverse general anesthesia. We previously reported that caffeine can accelerate emergence from anesthesia in rodents. This study was carried out to test the hypothesis that caffeine accelerates emergence from anesthesia in humans.” Although the study sample size was small, the results were notable.

The single-center, randomized, double-blind crossover study was conducted using eight healthy male volunteers, each of whom received two administrations of 1.2% isoflurane for 1 hour. During the final 10 minutes of each administration period, the subjects received either saline as placebo or an IV infusion of caffeine citrate (15 mg/kg, equivalent to 7.5 mg/kg of caffeine base). The team evaluated the primary outcome, established as the average difference in time to awaken after the isoflurane was discontinued in both populations—reported to be a difference of 6.9 min (99% CI, 1.8 to 12)—translating to a 42% reduction in time to awaken in those patients given caffeine. Secondary study outcomes included the patients’ vital signs, bispectral index values measured throughout anesthesia and emergence, and the isoflurane concentration at time of emergence (end-tidal).

Additional endpoints related to data gathered from psychomotor testing administered post anesthesia. The patients who received caffeine not only emerged from anesthesia more quickly, but they were also able to participate in psychomotor testing sooner—even at higher isoflurane concentrations. The authors noted that there were no statistically significant changes in patient vital signs or serious caffeine-related adverse drug effects observed during the study, concluding,  “Intravenous caffeine is able to accelerate emergence from isoflurane anesthesia in healthy males without any apparent adverse effects.”

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