Association Between Injected Volume and Epidural Blood Patch Success on Obstetric Post-Dural-Puncture Headache: A Retrospective Cohort Study.

BACKGROUND

Post-dural-puncture headache (PDPH) is a common complication of neuraxial procedures used during labor and delivery, affecting about 1% of patients. Epidural blood patch (EBP) is the most effective treatment for PDPH, but few studies assess the success of an EBP based on the volume of injected blood, especially >20 mL. Our practice is injection until the patient feels persistent back pressure. We aimed to determine whether the volume of injected blood was associated with an improved outcome after an EBP in the obstetric population.

METHODS

We reviewed records for patients receiving EBP after an obstetric epidural procedure over a 10-year period (May 2014-February 2024) at a single tertiary academic medical center. The primary outcome was failure of the first EBP, defined by the patient receiving a second EBP for treatment. Secondary outcome included the complete resolution of symptoms after the primary EBP. We used a binomial generalized model to identify factors associated with the success of the primary EBP. A value of P ≤ .05 was considered statistically significant.

RESULTS

Records from 317 patients were available, and we excluded 32 patients who received only single-shot spinal anesthesia from the primary analysis. Repeat EBP was performed in 65 (22.8%, 95% confidence interval [CI], 18.1%-28.1%) patients. In univariable analyses, the injected volume during EBP (median 28.0 mL, interquartile range [IQR] (22.0-32.0)), days from procedure to PDPH diagnosis, and from PDPH to EBP were associated with a successful EBP. In multivariable analyses, injected volume (odds ratio [OR] 0.96 per 1 mL, P = .028, 95% CI, 0.92-0.999) and days from PDPH diagnosis to EBP (OR 0.61 per day, P = .002, 95% CI, 0.43-0.81) were significantly associated with successful EBP. An analysis of the relationship between injected volume and repeated EBP suggested a dose-response relationship ( P = .030). Complete symptomatic follow-up data documented for at least 3 days were available for 226 patients, and headache was completely resolved in 118 (52.2%, 95% CI, 45.5%-58.9%). In a multivariable analysis, a dichotomous division of the population revealed a significant association with headache resolution in the group receiving an injected volume of ≥30 mL compared with patients receiving <30 mL (OR 1.85, P = .049, 95% CI, 1.01-3.47).

CONCLUSION

We found that a larger injected volume of blood during an EBP was associated with a reduced likelihood of receiving a second EBP. Injection of 30 mL or more was significantly associated with complete resolution of headache symptoms after the first EBP. A prospective trial to determine the etiology of this relationship is warranted.