Elizabeth M. S. Lange

The Relationship of Body Mass Index with the Incidence of Postdural Puncture Headache in Parturients.

BACKGROUND:Unintentional dural puncture is a known risk after epidural or combined spinal–epidural procedures, occurring in approximately 1% of labor epidural catheters placed in parturients with normal body habitus but may be as high as 4% in morbidly obese parturients. Anecdotal experience and limited publications suggest that an inverse relationship between body mass index (BMI) and postdural puncture headache (PDPH) may exist. We hypothesized that parturients with increased BMI have a lower incidence of PDPH than those with a lower BMI after unintentional dural puncture. METHODS:After IRB approval, we performed a retrospective cohort study by medical record review. Case logs from our institution were searched for patients with documented unintentional dural puncture during attempted neuraxial analgesia between January 1, 2004, and December 13, 2013. The primary outcome was the incidence of PDPH. The association between BMI and PDPH was assessed using binary logistic regression, and the Wilcoxon-Mann-Whitney odds and confidence intervals (CIs) for a random pair of BMI values from a PDPH subject compared with a non-PDPH subject were calculated from the area under the receiver operator characteristics curve. Classification tree analysis was used to determine the BMI cutoff value for the risk of developing a PDPH. The presence or absence of second-stage labor pushing and placement of an intrathecal catheter after unintentional dural puncture were compared in parturients with and without PDPH using the Fisher exact test. BMI groups were dichotomized at the cutoff value (low and high BMI groups). We compared the incidence of a PDPH between high and low BMI groups using the Fisher exact test after controlling for pushing during labor and placement of an intrathecal catheter at the time of unintentional dural puncture. Secondary analysis evaluated the highest reported numeric rating of pain scores for headache and the need for an epidural blood patch between BMI groups. RESULTS:Unintentional dural puncture was identified in 518 (0.53%) patients (95% CI, 0.48%–0.58%). The overall incidence of PDPH after unintentional dural puncture was 51% (95% CI, 46%–55%). The Wilcoxon-Mann-Whitney odds for a random pair of BMI values from a PDPH subject compared with a non-PDPH subject was 0.74 (95% CI, 0.60–0.90, P = 0.001). The odds ratio for developing a PDPH in women who pushed during delivery was 2.4 (95% CI, 1.2–3.9, P = 0.001) compared with women who did not push. Classification tree analysis identified a BMI cutoff value of 31.5 kg/m2 for prediction of a PDPH. The incidence of PDPH in parturients with a BMI ≥31.5 kg/m2 (39%) was lower than in parturients with a BMI <31.5 kg/m2 (56%; difference −17%; 95% CI, −7% to −26%, P = 0.0004). The odds ratio for a PDPH in the high BMI compared with the low BMI group was 0.36 (95% CI, 0.14–0.92, P = 0.04) in parturients who pushed during labor and 0.62 (95% CI, 0.41–0.97, P = 0. 04) in parturients who did not push. After the unintentional dural puncture, 112 (22%) parturients had an intrathecal catheter placed. The incidence of PDPH in parturients with an intrathecal catheter was 59% (95% CI, 49%–68%) compared with 48% (95% CI, 43%–54%) in women with an epidural catheter (P = 0.06). Median (interquartile range) headache severity (0–10 verbal rating scale) was 8 (6–9) and did not differ between parturients in the high versus low BMI groups (P = 0.61). The rate of epidural blood patch administration for PDPH treatment was similar in BMI groups (difference −12%; 95% CI, 4 to −27, P = 0.13). CONCLUSIONS:The findings are consistent with previous reports of decreased PDPH incidence after unintentional dural puncture in parturients with an increased BMI, even after controlling for pushing during labor. Severity of headache and need for epidural blood patch treatment were similar in low and high BMI groups.

Readability, content, and quality of online patient education materials on preeclampsia.

Objective: The objective of this study was to evaluate the readability, content, and quality of patient education materials addressing preeclampsia. Methods: Websites of U.S. obstetrics and gynecology residency programs were searched for patient education materials. Readability, content, and quality were assessed. A one-sample t-test was used to evaluate mean readability level compared with the recommended 6th grade reading level. Results: Mean readability levels were higher using all indices (p < 0.001). Content was variable with good website understandability, but poor actionability. Conclusions: The mean readability was above the recommended 6th grade reading level. The content, readability, and actionability of preeclampsia patient education materials should be improved.

An in vitro evaluation of the pressure generated during programmed intermittent epidural bolus injection at varying infusion delivery speeds

STUDY OBJECTIVE Programmed intermittent bolus injection of epidural anesthetic solution results in decreased anesthetic consumption and better patient satisfaction compared with continuous infusion, presumably by better spread of the anesthetic solution in the epidural space. It is not known whether the delivery speed of the bolus injection influences analgesia outcomes. The objective of this in vitro study was to determine the pressure generated by a programmed intermittent bolus pump at 4 infusion delivery speeds through open-ended, single-orifice and closed-end, multiorifice epidural catheters. DESIGN In vitro observational study. SETTING Not applicable. PATIENTS Not applicable. INTERVENTIONS A CADD-Solis Pain Management System v3.0 with Programmed Intermittent Bolus Model 2110 was connected via a 3-way adapter to an epidural catheter and a digital pressure transducer. Pressures generated by delivery speeds of 100, 175, 300, and 400 mL/h of saline solution were tested with 4 epidural catheters (2 single orifice and 2 multiorifice). These runs were replicated on 5 pumps. Analysis of variance was used to compare the mean peak pressures of each delivery speed within each catheter group (single orifice and multiorifice). MAIN RESULTS Thirty runs at each delivery speed were performed with each type of catheter for a total of 240 experimental runs. Peak pressure increased with increasing delivery speeds in both catheter groups (P<.001). Peak pressures were higher with the multiorifice catheter compared with the single-orifice catheter at all delivery speeds (P<.001, for all). CONCLUSION Using a pump designed for programmed intermittent infusion boluses, the delivery speed of saline solution through epidural catheters was directly related to the peak pressures. Future work should evaluate whether differences in the delivery speed of anesthetic solution into the epidural space correlate with differences in the duration and quality of analgesia during programmed intermittent epidural bolus delivery.

Effect of Epidural Infusion Bolus Delivery Rate on the Duration of Labor AnalgesiaA Randomized Clinical Trial

Background: Programmed intermittent boluses of local anesthetic have been shown to be superior to continuous infusions for maintenance of labor analgesia. High-rate epidural boluses increase delivery pressure at the catheter orifice and may improve drug distribution in the epidural space. We hypothesized that high-rate drug delivery would improve labor analgesia and reduce the requirement for provider-administered supplemental boluses for breakthrough pain. Methods: Nulliparous women with a singleton pregnancy at a cervical dilation of less than or equal to 5 cm at request for neuraxial analgesia were eligible for this superiority-design, double-blind, randomized controlled trial. Neuraxial analgesia was initiated with intrathecal fentanyl 25 &mgr;g. The maintenance epidural solution was bupivacaine 0.625 mg/ml with fentanyl 1.95 &mgr;g/ml. Programmed (every 60 min) intermittent boluses (10 ml) and patient controlled bolus (5 ml bolus, lockout interval: 10 min) were administered at a rate of 100 ml/h (low-rate) or 300 ml/h (high-rate). The primary outcome was percentage of patients requiring provider-administered supplemental bolus analgesia. Results: One hundred eight women were randomized to the low- and 102 to the high-rate group. Provider-administered supplemental bolus doses were requested by 44 of 108 (40.7%) in the low- and 37 of 102 (36.3%) in the high-rate group (difference –4.4%; 95% CI of the difference, –18.5 to 9.1%; P = 0.67). Patient requested/delivered epidural bolus ratio and the hourly bupivacaine consumption were not different between groups. No subject had an adverse event. Conclusions: Labor analgesia quality, assessed by need for provider- and patient-administered supplemental analgesia and hourly bupivacaine consumption was not improved by high-rate epidural bolus administration.

Racial and ethnic disparities in obstetric anesthesia

Racial and ethnic disparities are prevalent within healthcare and have persisted despite advances in medicine and public health. Disparities have been described in the use of neuraxial labor analgesia, with minority women being less likely to use neuraxial labor analgesia than non-minority white women. Minority women are also more likely to have a general anesthetic for cesarean delivery than non-minority women. The origins of these disparities are likely multi-factorial, with patient-, provider-, and systems-level contributors. The purpose of this article is to give an overview of disparities in obstetric anesthesia.

Association between intrapartum magnesium administration and the incidence of maternal fever: A retrospective cross-sectional study

Background: Intrapartum maternal fever is associated with several adverse neonatal outcomes. Intrapartum fever can be infectious or inflammatory in etiology. Increases in interleukin 6 and other inflammatory markers are associated with maternal fever. Magnesium has been shown to attenuate interleukin 6–mediated fever in animal models. We hypothesized that parturients exposed to intrapartum magnesium would have a lower incidence of fever than nonexposed parturients. Methods: In this study, electronic medical record data from all deliveries at Northwestern Memorial Hospital (Chicago, Illinois) between 2007 and 2014 were evaluated. The primary outcome was intrapartum fever (temperature at or higher than 38.0°C). Factors associated with the development of maternal fever were evaluated using a multivariable logistic regression model. Propensity score matching was used to reduce potential bias from nonrandom selection of magnesium administration. Results: Of the 58,541 women who met inclusion criteria, 5,924 (10.1%) developed intrapartum fever. Febrile parturients were more likely to be nulliparous, have used neuraxial analgesia, and have been delivered via cesarean section. The incidence of fever was lower in women exposed to magnesium (6.0%) than those who were not (10.2%). In multivariable logistic regression, women exposed to magnesium were less likely to develop a fever (adjusted odds ratio = 0.42 [95% CI, 0.31 to 0.58]). After propensity matching (N = 959 per group), the odds ratio of developing fever was lower in women who received magnesium therapy (odds ratio = 0.68 [95% CI, 0.48 to 0.98]). Conclusions: Magnesium may play a protective role against the development of intrapartum fever. Future work should further explore the association between magnesium dosing and the incidence of maternal fever.