HOLLYWOOD, FLA. — Remifentanil was found to be effective and safe for labor analgesia in a small randomized controlled study, Dr. Mrinalini Balki reported at the annual meeting of the Society for Obstetric Anesthesia and Perinatology.
A total of 15 women were randomized to receive either a fixed bolus/increasing infusion regimen, or a fixed infusion/increasing bolus regimen of the short-acting opioid analgesic.
The groups had similar overall median satisfaction scores (9 and 9 on a 0–10 scale), and pain scores (6 and 7 on a 0–10 scale), but maternal side effects were more common in the fixed infusion group, and pain control appeared to be less effective in that group, said Dr. Balki of the University of Toronto.
For example, 38% in the fixed bolus group, compared with 100% in the fixed infusion group, experienced drowsiness. Desaturation was noted in 13% in the fixed bolus group, compared with 57% in the fixed infusion group. And effective pain control, as measured by successful patient-controlled analgesia attempts (74% vs. 56%) and drug consumption (407 ng vs. 532 ng), was more common in the fixed bolus group.
Patients in both groups were treated with remifentanil infusion at 0.025 mcg/kg per minute, and patients were offered a patient-controlled analgesia bolus of 0.25 mcg/kg, with a lockout interval of 2 minutes.
The fixed-bolus group had infusions increased in a stepwise manner from 0.025 to 0.05, 0.075, and 0.1 mcg/kg minute as needed, and the bolus was fixed at 0.25 mcg/kg.
In the fixed infusion group, the infusion was fixed at 0.025 mcg/kg per minute and the bolus was increased from 0.25 to 0.5, 0.75, and 1 mcg/kg as needed.
Patient satisfaction in both groups was high, despite high pain scores.
This could reflect patient motivation or altered pain perception among those who choose remifentanil, Dr. Balki explained.
Since those in the fixed bolus group had better pain scores and required less drug, this regimen appears superior.
Neonatal safety was also similar in the two groups. A nonreassuring fetal heart rate was noted in one fetus in the fixed-bolus and in none of those in the fixed-infusion group, and Apgar scores were greater than 7 in all babies in both groups, Dr. Balki noted.