Major Finding: Patients in the ketamine group reported significantly less pain at 6 weeks post partum, with scores of 1.3 vs. 2.3, but there were no significant differences at 6 weeks in depression or at 1 year in pain or depression.
Data Source: One-year follow-up of 82 parturients from an initial randomized, controlled trial of 188.
Disclosures: None was reported.
SAN ANTONIO – A single postpartum low dose of ketamine significantly and persistently reduced pain for up to 6 weeks after cesarean delivery compared with placebo, but there were no significant differences in chronic pain or depression between the two groups at 1 year, in a randomized, double-blind study of 82 women.
Low doses of the N-methyl-
A total of 188 women were randomized to receive either 10 mg IV ketamine or saline by a blinded anesthesiologist 5 minutes after cesarean delivery. All received scheduled IV ketorolac 30 mg every 6 hours for 24 hours, along with 1 or 2 tablets of acetaminophen 325 mg/hydrocodone 10 mg every 4 hours as needed for breakthrough pain.
Among those 188 women, the group who received ketamine reported significantly lower numeric pain rating scores (on a scale of 1-10) than did those receiving saline. However, there were no differences at any other time point, Dr. Chalifoux reported at the meeting.
The 82 patients who were available for an interview 1 year later were asked to report pain scores (1-10) and whether they had a self-diagnosis of depression at both 6 weeks and 1 year post partum. Patients in the ketamine group reported significantly less pain at 6 weeks post partum, with scores of 1.3 vs. 2.3. Depression did not differ at 6 weeks, with just one woman (2%) from each group reporting that she was depressed at that point.
At 1 year, pain scores were nearly 0 in both groups and did not differ significantly (0.1 with ketamine vs. 0.0 with saline). Depression also did not differ significantly, although there were two women (5%) who reported being depressed at 1 year in the saline group compared with none in the ketamine group.
It's possible that a higher dose than 10 mg might have had a greater impact, given that the previous studies showing analgesic and antidepressive effects used doses ranging from 0.15 to 1.0 mg/kg. However, the potential side effects of ketamine – including dysphoria, memory loss, hallucinations, seizures, nystagmus, hypertension, tachycardia, and nausea/vomiting – suggest that dosages should be kept in the lower ranges, Dr. Chalifoux noted.
Also, it's possible that ketamine might not have a large impact among healthy parturients, but it might among those who are at increased risk for depression or chronic pain, she said.