Neuraxial labor analgesia failure rates in women with a body mass index ≥50 kg/m2: a single-center retrospective study.

BACKGROUND: The failure rate of neuraxial labor analgesia has not been investigated in super-obese women (body mass index ≥50 kg/m2). METHODS: We performed a retrospective study of neuraxial labor analgesia in super-obese women (January 2012 to August 2019). The primary outcome was the failure rate of the first neuraxial catheter. Secondary outcomes were failure rates by neuraxial technique, at cesarean delivery, and rate of catheter replacement. RESULTS: Neuraxial labor analgesia was used by 233 super-obese women: 153 epidural catheters placed using a combined spinal-epidural (CSE) or dural puncture epidural techniques with visualization of cerebrospinal fluid; 63 placed without dural puncture (including procedures without attempted dural puncture or attempted CSE or dural puncture epidural); and 17 intrathecal catheters (seven intentional). Thirty-two of 233 neuraxial catheters failed (13.7%, 95% Confidence Interval [CI] 9.9 to 18.7%). Epidural catheters placed using CSE or dural puncture epidural had a lower failure rate than those placed without dural puncture (9.2%, 95% CI 5.5% to 14.7%) vs 28.6% (95% CI 18.9% to 40.7%; P<0.001). Catheter migration was documented for 29.4% (95% CI 16.8 to 46.2%) of catheters that failed. CONCLUSIONS: Epidural catheters placed using CSE or dural puncture epidural techniques were more reliable than those placed without dural puncture in super-obese parturients. It is unclear whether the result was driven by grouping procedures without attempted dural puncture with those in which dural puncture was attempted but cerebrospinal fluid was not obtained. Catheter migration was a major source of failure.

Inadvertent neuraxial block placement at or above the L1-L2 interspace in the super-obese parturient: a retrospective study.

BACKGROUND: Increasing body mass index (BMI) increases the difficulty of neuraxial procedures. We hypothesized that it may put patients at risk for inappropriately high dural puncture. The accuracy of anesthesiologists' estimates of the interspinous level in super-obese parturients has not been studied. We evaluated the frequency of inadvertently high epidural and/or intrathecal catheter placement (at or above the L1/L2 interspace) in parturients of BMI ≥50 kg/m2. METHODS: Inclusion criteria for this retrospective study were women with a BMI ≥50 kg/m2 who delivered by cesarean with an epidural or intrathecal catheter. The primary outcome was the percentage of catheters placed at or above L1/L2, determined by reviewing the retained foreign object radiograph. Secondary outcomes were agreement between the estimated and actual catheter location and subgroup analysis of catheters placed under ultrasound guidance. RESULTS: After excluding 15 cases for which the catheter location could not be determined and 10 cases for which the estimated level of insertion was not recorded, 125 cases were included. Inadvertent high placement occurred in 26/125 (21%, 95% confidence interval (CI) 15% to 29%) patients. There was poor agreement between the estimated and actual catheter location (27% accurate, unweighted κ-statistic 0.02). Eleven of 39 catheters placed with ultrasound (28%, 95% CI 17% to 44%) were at or above L1/L2 compared with 15/86 catheters placed without ultrasound (17%, 95% CI 11% to 27%, P=0.17). There were no neurological complications. CONCLUSIONS: A high rate of inadvertently high epidural or intrathecal catheter placement occurs in super-obese parturients. Ultrasound did not prevent this.

Outcomes after institution of a new oxytocin infusion protocol during the third stage of labor and immediate postpartum period.

BACKGROUND: Due to safety concerns when oxytocin is administered in an uncontrolled fashion, and recent dose-response data that indicate oxytocin's effectiveness at doses lower than those traditionally used, we instituted a new protocol for the infusion of oxytocin during the third stage of labor and in the immediate postpartum period. We undertook this study to confirm that this change in practice did not have untoward effects on postpartum hemorrhage rates. METHODS: In this retrospective review, patients who delivered in the six months before (PRE group) and patients who delivered in the six months after (POST group) the new protocol had been introduced were identified through an institutional database and their medical records were reviewed. The primary outcome variable was the postpartum hemorrhage rate. Secondary outcomes included maternal and fetal co-morbidities, protocol compliance, administration of other uterotonic agents, use of Bakri balloons and B-Lynch sutures, rate of uterine artery embolization and peripartum hysterectomy, need for red blood cell transfusion, and drop in hemoglobin after delivery. Categorical data were analyzed using Chi-squared or Fisher's Exact test, as appropriate. Continuous data were analyzed using a Mann-Whitney U test. A P value <0.05 was required to reject the null hypothesis. RESULTS: A total of 1572 medical records were reviewed. Postpartum hemorrhage occurred in 9.0% of PRE patients and 7.1% of POST patients, and was not different between groups (P=0.17). Carboprost use was lower in the POST group, but no other differences were noted. CONCLUSION: Adoption of a protocol to infuse oxytocin in a controlled manner at a lower dose than that historically used was not associated with an increased incidence of postpartum hemorrhage.

The effect of intravenous magnesium therapy on the duration of intrathecal fentanyl labor analgesia.

BACKGROUND: Magnesium has been reported to augment the analgesic effects of opioids when co-administered into the cerebrospinal fluid. The purpose of this study was to determine the influence of intravenous magnesium therapy administered for preeclampsia on the duration of intrathecal fentanyl analgesia for labor. METHODS: Thirty-four nulliparous parturients having labor induced for preeclampsia and receiving intravenous magnesium therapy were recruited. Thirty-four nulliparous patients having labor induced for elective or medical reasons were recruited as controls. At request for analgesia, baseline serum magnesium levels were obtained and combined spinal-epidural analgesia was initiated with intrathecal fentanyl 25µg. Before injection of fentanyl, a sample of cerebrospinal fluid was obtained for magnesium assay. An epidural catheter was sited but no additional medications were administered until the second request for analgesia. The primary outcome was duration of intrathecal fentanyl analgesia. RESULTS: There was no difference in the median duration of analgesia between the magnesium [79min (95% CI 76 to 82)] and control groups [69min (95% CI 56 to 82)] (difference between medians: 10min (95% CI -4 to 21min; P=0.16). There was neither a relationship between the serum and cerebrospinal fluid magnesium concentrations nor the cerebrospinal magnesium concentration and duration of intrathecal fentanyl analgesia. CONCLUSIONS: Intravenous magnesium therapy at doses typically used for seizure prophylaxis in preeclampsia did not influence the duration of intrathecal fentanyl labor analgesia. However, this study may have been underpowered to detect a difference and future study is warranted.

A randomized controlled trial of the effect of combined spinal-epidural analgesia on the success of external cephalic version for breech presentation.

BACKGROUND: Improving the success of external cephalic version (ECV) for breech presentation may help avoid some cesarean deliveries. The results of randomized trials comparing the success of ECV with neuraxial analgesia compared to control are inconsistent. We hypothesized that combined spinal-epidural (CSE) analgesia would increase the success of ECV when compared with systemic opioid analgesia. METHODS: Parturients with singleton breech presentation (n=96) were randomized to receive CSE analgesia with bupivacaine 2.5mg and fentanyl 15 microg (CSE group) or intravenous fentanyl 50 microg (SYS group) before ECV attempt. The primary outcome was ECV success. RESULTS: The success rate of ECV was 47% with CSE and 31% in the SYS group (P=0.14). Subsequent vaginal delivery was 36% for CSE and 25% for SYS (P=0.27). Median [IQR] visual analog pain scores (0-100mm scale) were lower with CSE (3 [0-12]) compared to SYS analgesia (36 [16 to 54]) (P<0.005) and patient satisfaction (0-10 scale) was higher (CSE 10 [9 to 10] versus SYS 7 [4 to 9]) (P<0.005). There were no differences in fetal heart rate patterns, but median time to return to fetal heart rate reactivity after analgesia was shorter with CSE (13 [IQR 9-21] min) compared to the SYS group (39 [IQR 23-51] min) (P=0.02). CONCLUSIONS: There was no difference in the rate of successful ECV or vaginal delivery with CSE compared to intravenous fentanyl analgesia. Pain scores were lower and satisfaction higher with CSE analgesia, and median time to fetal heart rate reactivity was shorter in the CSE group.

Efficacy and side effect profile of varying doses of intrathecal fentanyl added to bupivacaine for labor analgesia.

The purpose of this randomized, double blinded and controlled study was to determine the optimal dose of intrathecal fentanyl when combined with bupivacaine 2.5 mg for initiation of labor analgesia. Parous parturients with cervical dilation between 3 and 5 cm were randomized to receive intrathecal fentanyl 0 (control), 5, 10, 15, 20 or 25 micrograms, combined with bupivacaine 2.5 mg, followed by a lidocaine/epinephrine epidural test dose. Visual analog pain scores (VAPS) and the presence of side effects were determined every 15 min until the parturient requested additional analgesia. Fetal heart rate (FHR) tracings were compared between groups. All parturients who received fentanyl >/= 15 micrograms had VAPS < 20 mm and duration of analgesia > 15 min, but this was not true for all parturients with fentanyl doses < 15 micrograms. Duration of analgesia was shorter for fentanyl groups 0, 5 and 10 micrograms, compared to groups 15, 20 and 25 micrograms, but there was no difference between the 15, 20 and 25 micrograms groups. There was no difference in the incidence of nausea and vomiting, or in FHR tracing changes. The incidence of pruritus was greater in all fentanyl groups compared to control. These data suggest that, when combined with intrathecal bupivacaine 2.5 mg, fentanyl 15 micrograms provides satisfactory analgesia to all parturients. Higher fentanyl doses produced no additional benefit in duration or quality of analgesia.

The dose-response of intrathecal sufentanil added to bupivacaine for labor analgesia.

BACKGROUND: Regional analgesia for labor often is initiated with an intrathecal injection of a local anesthetic and opioid. The purpose of this prospective, randomized, blinded study was to determine the optimal dose of intrathecal sufentanil when combined with 2.5 mg bupivacaine for labor analgesia. METHODS: One hundred seventy parous parturients with cervical dilation between 3-5 cm were randomized to receive intrathecal 0 (control), 2.5, 5.0, 7.5, or 10.0 microg sufentanil combined with 2.5 mg bupivacaine, followed by a lidocaine epidural test dose, for initiation of analgesia (34 patients in each group). Visual analog scores and the presence of nausea, vomiting, and pruritus were determined every 15 min until the patient requested additional analgesia. Fetal heart rate tracings were compared between groups. RESULTS: Groups were similar for age, height, weight, oxytocin dose, duration of labor, and baseline visual analog scores. Duration of action was significantly shorter for control patients (39 +/- 25 min [mean +/- SD]) compared with those administered sufentanil, all doses (93 +/- 32, 93 +/- 47, 94 +/- 33, 97 +/- 39 min), but was not different among groups administered 2.5, 5.0, 7.5, or 10.0 microg sufentanil. More patients who received 10 microg sufentanil reported nausea and vomiting than did control patients. The severity of pruritus increased with administration of 7.5 and 10.0 microg sufentanil. There was no difference in fetal heart rate changes among groups. CONCLUSIONS: Intrathecal bupivacaine (2.5 mg) without sufentanil did not provide satisfactory analgesia for parous patients. However, bupivacaine combined with 2.5 microg sufentanil provided analgesia comparable to higher doses, with a lower incidence of nausea and vomiting and less severe pruritus.