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-d-aspartate (NMDA) antagonist ketamine have been shown to decrease postoperative opioid requirements, and the drug has also been shown to have an antidepressive effect (Arch. Gen. Psychiatry 2006;63:856–64). hhose data led to the hypothesis that women who receive a single intravenous dose of ketamine might be less likely to develop postpartum depression or chronic pelvic pain, said Dr. Laurie Chalifoux of Northwestern University, Chicago.
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.