Neuraxial morphine after unintentional dural puncture is not associated with reduced postdural puncture headache in obstetric patients

Abstract

Study objective: To examine the relationship between neuraxial morphine exposure after unintentional dural puncture and the risk for postdural puncture headache in obstetric patients.

Design: Retrospective cohort study.

Setting: Obstetrical unit at a tertiary care referral center.

Patients: Parturients receiving labor epidural analgesia with recognized unintentional dural puncture.

Interventions: Cases in which neuraxial morphine was given for any reason were compared to cases in which it was not for the outcome of postdural puncture headache.

Measurements: Development of postdural puncture headache, headache severity, number of epidural blood patches, hospital length of stay.

Main results: Of the 80 cases that were included, 38 women received neuraxial morphine and 42 did not. There was no significant difference in the incidence of headache between the two morphine groups (Headache present: Morphine: 27/56 [48.2%], No morphine: 29/56 [51.8%]; Headache free: Morphine: 11/24 [45.8%], No morphine: 13/24 [54.2%], P = 0.84). There was no difference in the need for epidural blood patch (Morphine: 24/42 [57.1%], No morphine: 18/38 [47.4%], P = 0.50) and headache severity (mean headache pain score: Morphine: 7.9 ± 1.8 vs. No morphine: 7.3 ± 2.4, P = 0.58). Hospital length of stay was higher in the morphine group (4.4 ± 2.9 days vs. 3.0 ± 1.5 days respectively, P = 0.008). Using logistic regression, morphine did not affect headache risk after controlling for covariates (morphine vs. no morphine: adjusted OR 1.24 [0.75]; P = 0.72; pre-eclampsia vs. no pre-eclampsia: adjusted OR 0.56 [0.41], P = 0.42; cesarean vs. normal spontaneous vaginal delivery: adjusted OR 0.97 [0.67]; P = 0.96).

Conclusion: In cases of unintentional dural puncture, exposure to neuraxial morphine for any reason may not be protective against the risk of postdural puncture headache. Although an overall protective effect of neuraxial morphine was not observed in this study, its role in specific subsets of patients remains to be investigated.

Keywords: Epidural; Morphine; Postdural puncture headache; Spinal.