Assessment of role of perioperative melatonin in prevention and treatment of postoperative delirium after hip arthroplasty under spinal anesthesia in the elderly.

Context: Little is known about the relationship between sedative drugs used preoperatively and postoperative delirium. Melatonin is a drug used to sedate patients preoperatively and is hypothesized by recent works to have a curative effect on postoperative delirium.

Aims: The incidence of postoperative delirium will be tested if affected by three different sedative drugs including melatonin.

Settings And Design: Controlled randomized doubleblind study.

Patients And Methods: Three-hundred patients aged>65 years scheduled for hip arthroplasty under spinal anesthesia were randomly distributed to one of the four groups. Group 1 (control) received nothing for sedation. Group 2 (melatonin) received 5 mg melatonin. Group 3 (midazolam) received 7.5 mg midazolam. Group 4 (clonidine) received 100 μg clonidine. These medications were given orally at sleep time at night of operation and another dose 90 min before operative time. Patients who developed postoperative delirium received 5 mg of melatonin 9 pm for three successive days in a trial to treat delirium.

Statistical Analysis Used: Statistical analysis was done using the SPSS Software (version 13).

Results: Total of 222 patients completed the study. Percentage of postoperative delirium in the control group was 32.65% (16/49 patients). The melatonin group showed a statistically significant decrease in the percentage of postoperative delirium to 9.43% (5/53 patients). Melatonin was successful in treating 58.06% of patients suffered postoperative delirium (36/62 patients) with no difference between different groups.

Conclusions: Postoperative delirium is affected with the drug used for preoperative sedation. Melatonin was successful in decreasing postoperative delirium when used preoperatively and in treating more than half of patients developed postoperative delirium when used for three postoperative nights.