• Shiho Yoshitaka, Moritoki Egi, Tomoyuki Kanazawa, Yuichiro Toda, and Kiyoshi Morita.
• Department of Anesthesiology and Resuscitology, Okayama University Medical School, Okayama, Japan.
• Crit Care Resusc. 2014 Dec 1;16(4):269-73.

ObjectiveDelirium is a common complication in postoperative, critically ill patients. The mechanism of postoperative delirium is not well understood but many studies have shown significant associations between benzodiazepine use, alcohol withdrawal and cirrhosis, and an increased risk of delirium. We aimed to investigate a possible link with alterations of gamma-aminobutyric acid (GABA) activity.Design, Setting And ParticipantsA prospective observational investigation of 40 patients > 20 years old who had undergone elective surgery with general anaesthesia and were expected to need postoperative intensive care for more than 48 hours. We assessed postoperative delirium using the confusion assessment method in the intensive care unit at 1 hour after the operation and on postoperative Day (POD) 1 and POD 2. We collected blood samples for measurement of plasma GABA concentrations before the operation and on POD 1 and 2.Main Outcome MeasuresPostoperative delirium and perioperative plasma GABA concentrations in patients with and without delirium.ResultsPostoperative delirium occurred in 13 of the patients. Patients with delirium had significantly higher Acute Physiology and Chronic Health Evaluation II scores than patients without delirium. The mean plasma GABA concentration on POD 2 was significantly lower in patients with delirium than in those without delirium. After adjustment of relevant variables, plasma GABA concentration on POD 2 was independently associated with postoperative delirium.ConclusionsPlasma GABA level on POD 2 has a significant independent association with postoperative delirium.

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