Postdural puncture headache (PDPH) is an unfortunate complication of neuraxial anesthesia. In obstetric patients, unintentional dural puncture (UDP) occurs at a rate of 1.5% (95% CI 1.5%–1.5%) during epidural catheter insertion; approximately half (52.1%, 95% CI 51.4%–52.8%) of these patients develop PDPH.1 The proposed mechanism of pain in PDPH is thought to be traction on the meninges and meningeal vessels when in the vertical position, resulting from loss of the cushioning effect of cerebrospinal fluid. An additional mechanism may involve reflex dilation of cerebral blood vessels, and subsequent stimulation of pain-sensitive stretch receptors.2
The International Headache Society defines PDPH as headache that is improved by the supine position within 15 minutes and exacerbated by sitting or standing upright within 15 minutes.3 Pain may be accompanied by neck stiffness, photophobia, hypacusia, nausea, or tinnitus. By definition, headache must develop within 5 days of dural puncture, although it usually presents within 1 to 2 days.1 It typically resolves spontaneously within 1 week or within 48 hours after treatment of the dural leak; however, symptoms can persist months to years.4 Pain can be severe, and frequently lasts longer and is more significant and disabling in obstetric patients than the general population. PDPH is associated with increased length of hospital stay after vaginal delivery.5
Because of the significance of the problem in both surgical and obstetric patients, practitioners have explored various prophylactic and therapeutic measures. The “gold standard” for treatment is the epidural blood patch (EBP). Therapeutic EBP is thought to exert its effect by sealing the dural leak and by immediately exerting a mass effect, thus increasing intraspinal pressure. The mass effect acts to propel cerebrospinal fluid into the cranium, thus increasing the intracranial pressure and mitigating vasodilation. Reports of therapeutic effectiveness range from 73% to 93%.6–10 Given this therapeutic efficacy of EBP in the treatment of PDPH, as well as the high incidence and severity of headaches in the obstetric population, it is logical to question whether EBP is useful for headache prophylaxis after dural puncture. This review focuses on the use in obstetric patients of a prophylactic EBP (PEBP): the injection of autologous blood into the epidural space after UDP to decrease the risk of developing PDPH.
The first report of PEBP was a nonrandomized, nonblinded trial of 200 patients undergoing spinal anesthesia for surgery or labor, half of whom received an injection of 2.5 mL autologous blood via the exiting 20-gauge spinal needle after injection of the intrathecal medications.11 The PEBP recipients demonstrated a reduced rate of PDPH (0% vs 15% control group, no P value reported). Statistical evaluation by the authors of this review, using the published summary data, reveals a difference in incidence of 0.15 (95% CI 0.08–0.22, P < 0.001).1a Another group used a similar technique to compare prophylactic blood versus saline patch after spinal anesthesia in 69 male surgical patients and reported no significant difference between groups.12 Although these authors should be credited with pioneering the concept of PEBP, the procedural details of the blood patch itself, including the questionable location of the blood clot, and use of a 20-gauge needle (presumably a cutting needle based on the timing of the report) for spinal anesthesia, make the studies less clinically relevant today.
Subsequent to these early reports, several case series addressed the use of PEBP specifically after UDP with an epidural needle. Quaynor and Corbey13 described 7 patients who experienced UDP while undergoing epidural anesthesia for a variety of surgical procedures. At the time of the dural puncture, PEBP was performed with 15 to 17 mL autologous blood via the epidural needle; none of the patients developed headache over the following week. A second report described 10 obstetric patients who received, after delivery, PEBP through an epidural catheter sited in the epidural space after the dural puncture; the PDPH rate was 10%.14 In a retrospective study, Ackerman and Colclough15 reported a lower rate of PDPH after accidental dural puncture in obstetric patients who were treated with PEBP (15 mL blood via the catheter 20 minutes after delivery, 0 of 6 patients) compared with patients who did not receive PEBP (5 of 5 patients), but did not report comparative statistics. Although these reports were encouraging, the lack of controlled comparisons and retrospective design limited the conclusions that could be drawn regarding efficacy of PEBP.
Nonrandomized comparisons of PEBP versus conservative treatment in obstetric patients who experienced UDP have been published (Table 1). Palahniuk and Cumming16 compared 11 obstetric patients who received PEBP (5 to 10 mL blood through an epidural catheter) at the discretion of the anesthesiologist with 75 patients who did not. There was no difference in the rate of PDPH or therapeutic blood patch between groups. Conversely, Trivedi et al.17 compared PEBP (15 mL blood) with prophylactic epidural saline (40–60 mL) injected through the catheter after delivery, or no intervention in 74 patients who had UDP during epidural placement for labor analgesia. Before epidural placement, patients selected their preferred method of management in the event of UDP. There was a significant reduction in headache rate in the PEBP group compared with the saline patch and control groups (5% vs 67% vs 88%, respectively, P < 0.001, current authors' calculation). These nonrandomized investigations, which lacked proper blinding and contained few specific protocols for diagnosis or treatment, are subject to the power of suggestion and more likely to show a positive effect where one may not exist. Because of this bias, they provide little guidance to the practitioner.
To address this uncertainty, 3 randomized controlled trials were performed and reported in the peer-reviewed literature, all of them in obstetric patients (Table 1).18–20 Ackerman et al.18 administered 18 to 20 mL blood through an epidural catheter versus no prophylaxis in 21 obstetric patients with UDP. Nonblinded subjects were followed by a blinded observer at 12 and 24 hours, and 5 days postpartum, but between these times follow-up was conducted by a nonblinded individual. At 24 hours, subjects in either group with severe positional headache received a therapeutic 15-mL blood patch. There was a difference in headache incidence (1 of 10 vs 7 of 11 in PEBP versus control group, respectively, P = 0.02), but no difference in administration of therapeutic EBP (1 of 10 vs 5 of 11; current authors' calculation: odds ratio ([OR] 0.13, 95% CI 0.01–1.44). The wide confidence interval for the odds ratio for the need for therapeutic EBP suggests that the study is underpowered to detect a difference, if it exists. Colonna-Romano and Shapiro,19 in a similar investigation, compared PEBP (15 mL blood administered via the in situ epidural catheter) versus oral hydration and unenforced bed rest in 39 obstetric patients. This study also demonstrated a reduced rate of PDPH in the patients who received PEBP (4 of 19 [21%] vs 16 of 20 [80%] in controls, P < 0.001), but no difference in administration of therapeutic EBP (3 of 19 vs 7 of 20; current authors' calculation: OR 0.35, 95% CI 0.075–1.62, P = 0.27). The study was limited by lack of proper randomization (the investigators used a sequential allocation strategy, and lack of blinding); both subjects and investigators were aware of group assignment. Additional limitations of both studies included lack of standard diagnostic and treatment protocols and small sample sizes.
There has been only 1 randomized, controlled, double-blind study assessing the efficacy of PEBP.20 The trial included 64 patients who had UDP with a 17-gauge epidural needle during placement of an epidural catheter for labor. After delivery, all patients had 20 mL blood drawn from an arm vein, and subsequently, a nonblinded anesthesiologist either injected the blood into the epidural catheter or pantomimed doing so in a sham procedure, keeping the syringe hidden from the patient, visitors, and caregivers. The epidural catheter was removed. Patients were followed by a blinded observer daily for 5 days if they did not develop a headache, or until 3 days after resolution of a headache. Standardized criteria were used to determine the need for subsequent therapeutic blood patch. Results differed from previous studies in that there was no difference in rate of headache between the PEBP and sham groups (18 of 32 [56%] in each group), peak pain scores (7 of 10 vs 6 of 10, PEBP versus controls, respectively, P = 0.21), nor in the incidence of need for therapeutic blood patch (11 of 32 [34%] vs 15 of 32 [47%], PEBP versus controls, respectively, P = 0.14; OR 0.59, 95% CI 0.22–1.63, current authors' calculation). There was a reduction in median duration of headache in the PEBP group compared with the sham group (5 vs 2 days, PEBP versus controls, respectively, P < 0.05); however, the lack of efficacy in preventing PDPH or need for therapeutic EBP in this patient population was disappointing. Explanations for the differences in results compared with the previous 2 studies include appropriate randomization, double-blinding, use of a standardized protocol for diagnosis and treatment of PDPH, and specific criteria for the recommendation of therapeutic EBP administration. In addition, the study may have been underpowered to detect the difference in the need for therapeutic blood patch between groups.
The distinction in level of evidence between retrospective and prospective data bears mentioning. The differences observed between treatments tend to appear greater in case reports and case series than in randomized, controlled, and blinded trials. As is often the case, a practice that garnered many favorable early reports, mostly in uncontrolled situations, failed to demonstrate great efficacy when subjected to rigorous scientific study. A meta-analysis, performed by Apfel et al.,21 included 9 studies with 236 patients comparing PEBP with other treatment after UDP with an epidural needle, and demonstrated a significant reduction in PDPH (relative risk [RR] 0.41, 95% CI 0.24–0.71). Because of significant heterogeneity in the studies, a sensitivity analysis was performed: among the 5 nonrandomized controlled trials, PEBP resulted in a significant reduction in the rate of PDPH (RR 0.48, 95% CI 0.23–0.99); however, analysis of 4 randomized controlled trials did not show a significant difference (RR 0.32, 95% CI 0.10–1.03). Indeed, Boonmak and Boonmak22 performed a quantitative review of PEBP and found insufficient evidence to recommend PEBP after dural puncture. Their analysis included 5 studies comparing PEBP with other treatment, with 221 participants culled from the obstetric and general surgical populations. This review, because it did not focus specifically on obstetric patients who had undergone UDP with a large-gauge epidural needle, may not have detected a benefit from PEBP in this patient population, which is traditionally considered to be a group with both a high incidence of PDPH and notable severity of symptoms.
Despite a lack of definitive evidence to support the practice, surveys reveal that PEBP use is not uncommon after UDP in the general and obstetric populations in North America (41%–46% of institutions or anesthesiologists surveyed in both studies, published in 1998 and 2009, respectively),23,24 although it is markedly less common in the United Kingdom, where 1% of centers routinely use the practice, as reported in a 2005 survey.25 In all 3 survey studies, the use of PEBP lags behind the most common prophylactic therapy, aggressive oral hydration (62%–92%).23–25
Although EBP is considered a relatively safe procedure, its performance does incur some risk. Therapeutic EBP has been associated with neurologic complications, such as low back pain, radiculitis, cauda equina syndrome, seizure, pneumocephalus, cranial nerve palsy, and worsened headache.26 Other potential complications include infections such as epidural abscess and meningitis. When PEBP is performed, the timing should be carefully considered to avoid complications. An instance of total spinal anesthesia was reported after PEBP was performed in a patient with a T4 blockade from epidural anesthesia, suggesting it is prudent to perform PEBP after complete resolution of neuraxial blockade.27 An additional benefit to waiting for block regression is the ability to detect whether the patient has pain with injection, which theoretically mitigates the risk of neurologic sequelae. Initial concerns about the inability to provide reliable epidural anesthesia after EBP seem insignificant, both immediately after PEBP and months to years afterward.28–31
Based on currently available data, it seems likely that PEBP does not confer a benefit in reducing the rate of PDPH in obstetric patients. It is not clear whether PDPH reduces the need for therapeutic EBP. A post hoc analysis of the Scavone et al.20 study indicated a need for a sample size of 476 patients to detect a difference in the rate of therapeutic EBP. Many unanswered questions remain. One possibility is that PEBP reduces the number of therapeutic EBPs required; perhaps patients with headache despite PEBP have worse headaches and would be in the group of patients who require multiple therapeutic EBPs. None of the randomized controlled trials discussed were powered for this outcome.18–20 Another unknown is the optimal end point for injection of blood, although a recent study of the volume of blood for therapeutic EBP suggested that optimal results may be obtained with approximately 20 mL of blood.32 It is not clear whether the efficacy of PEBP would improve if more volume was injected, or if the end point of the injection was patient-perceived back pressure, rather than a predetermined volume of blood. It is also unclear how these data may be generalized to the surgical population, with its lower incidence and severity of PDPH after UDP compared with those in the obstetric population.
In summary, PEBP does not seem to decrease the incidence of PDPH after UDP in obstetric patients. However, parturients may derive a benefit from PEBP in regard to intensity and/or duration of symptoms. Additionally, larger studies may confirm an advantage regarding the need for therapeutic blood patch. The anesthetic community should pursue larger, multicenter trials to investigate this question more fully. At this time, the data are not sufficient to routinely recommend the procedure even in the high-risk obstetric population.
Name: Ashley N. Agerson, MD.
Contribution: This author helped write the manuscript and review the literature.
Attestation: Ashley N. Agerson approved the final manuscript.
Name: Barbara M. Scavone, MD.
Contribution: This author helped write the manuscript and review the literature.
Attestation: Barbara M. Scavone approved the final manuscript.
This manuscript was handled by: Cynthia A. Wong, MD.
a Analysis was performed with Minitab 16 software (Minitab, Inc., State College, PA).
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