Hydrogen gas treatment improves postoperative delirium and cognitive dysfunction in elderly noncardiac patients

Abstract Background: Postoperative delirium, a common complication after surgery in elderly individuals, is a state of acute brain dysfunction characterized by fluctuating mental status that affects millions of patients each year. We used prophylactic inhalation of hydrogen gas with elderly patients undergoing elective surgery to compare their occurrence of postoperative delirium with that of controls.Methods: A total of 184 patients were enrolled and randomized into a control group and a hydrogen inhalation group. All the patients were >= 65 years of age. The quality of sleep was assessed 1 day before surgery and 1, 3, and 7 days after surgery at 8 AM. The Confusion Assessment Method (CAM) was used as a screening tool for delirium. The patients' postoperative state of consciousness was assessed using the CAM 1-7 days after surgery. If delirium was diagnosed, the time of onset and duration of delirium were recorded.Results: Postoperative delirium happened in 17 (24%) of 70 elderly noncardiac patients and in 10 (12%) of 83 patients after hydrogen inhalation. The incidence of delirium was decreased in the hydrogen group. No significance differences were found in length of stay in the hospital after surgery between the two groups. For additional outcomes, there was no significant difference in sleep quality between the two groups at 1, 3, and 7 days postoperatively, and the sleep quality gradually recovered over 7 days postoperatively. The numerical rating scale (NRS) pain scores were higher in the hydrogen group (4.08±1.77) than in the control group (3.54±1.77) on day 1 (P<0.05); however, the mean difference in NRS pain scores between the two groups was small (1 to 1.6). There was no significant difference on day 3 or 7. The postoperative C-reactive protein level was significantly lower in the hydrogen group than in the control group.Conclusions: This study suggests that hydrogen inhalation can prevent postoperative delirium in elderly noncardiac patients by reducing the inflammatory response.