Spread of subarachnoid sensory block with hyperbaric bupivacaine in second trimester of pregnancy

A retrospective cohort study of the anesthetic management of postpartum tubal ligation

BACKGROUND

Neuraxial anesthesia with reactivation of a labor epidural catheter is commonly utilized for postpartum tubal ligations (PPTL), although the optimal anesthetic approach is unknown. We assessed institutional anesthesia practices for PPTL, and evaluated the failure rates of reactivation of labor epidural catheters, de novo spinal anesthesia, and spinal anesthesia after failed blocks.

METHODS

We conducted a single-center retrospective cohort analysis of 300 consecutive patients who underwent a PPTL and 100 having spinal anesthesia for cesarean delivery. Anesthetic management data (existing labor epidural catheter reactivation, de novo spinal anesthesia or general anesthesia) were collected from electronic medical records. Anesthetic block failure rates were determined for each anesthetic technique.

RESULTS

The failure rate was 15% for de novo spinal anesthesia and 23% after failed reactivation of a labor epidural catheter or spinal anesthesia. The epidural catheter reactivation failure rate was 35%. The failure rate of spinal anesthesia for cesarean delivery was 4%. Drug dosage, epidural catheter use in labor, time since epidural catheter placement or delivery, labor neuraxial technique (combined spinal-epidural, epidural), supplemental top-up doses during labor, and anesthesiologist experience did not predict neuraxial anesthesia failures.

CONCLUSIONS

Our analysis revealed an unexpectedly high neuraxial anesthesia failure rate even when de novo spinal anesthesia was used for PPTL. The results are consistent with other institutions' recent findings, and are higher than spinal anesthesia failure rates associated with cesarean delivery. Further studies are required to determine optimal anesthesia dosing strategies, and to understand the mechanisms behind high neuraxial anesthesia failures for PPTL.

Median effective dose of ropivacaine for prophylactic cervical cerclage in Chinese women: a dose-finding study

BACKGROUND

Although intrathecal ropivacaine has been widely used for caesarean delivery, there are limited data for the use of ropivacaine for prophylactic cervical cerclage. We sought to determine the median effective dose of intrathecal ropivacaine for prophylactic cervical cerclage in 50% of patients (ED50) and the calculated dose required for successful block in 95% of patients (ED95).

METHODS

We included Chinese women scheduled for prophylactic cervical cerclage under combined spinal-epidural (CSE) anaesthesia in the first or second trimester. A predetermined dose of intrathecal isobaric ropivacaine was administered. If this determined dose achieved an effective block at a level not lower than T12, the next dose was decreased by 0.5 mg. Otherwise, the next dose was increased by 0.5 mg. The primary outcome was the ED50 of intrathecal ropivacaine. Secondary outcomes included the calculated ED95, time from CSE to the start of surgery and so on.

RESULTS

Forty patients were included in the study, 23 (57.5%) of 40 received an effective block only with intrathecal ropivacaine, while 17 (42.5%) patients needed extra epidural lidocaine to achieve a successful block. The ED50 of intrathecal ropivacaine confirmed by isotonic regression was 6.9 mg (95% CI, 6.68 to 7.12 mg), and the calculated ED95 was 7.8 mg (95% CI, 7.69 to 10.05 mg). When an effective block was achieved with intrathecal ropivacaine alone, the time to resolution of the sensory and motor blocks was 90 (75-100) min and 90 (60-100) min, respectively.

CONCLUSIONS

The ED50 of intrathecal ropivacaine for prophylactic cervical cerclage was 6.9 mg. Intrathecal ropivacaine (7.8 mg) is likely to produce successful anaesthesia in 95% of patients undergoing prophylactic cervical cerclage.

TRIAL REGISTRATION NUMBER

ChiCTR2100051418.

Correlation between gestational age and level of sensory block in spinal anesthesia

BACKGROUND AND OBJECTIVES

To identify a specific correlation between progression of gestational age and level of sensory block in spinal anesthesia in patients undergoing cervical cerclage.

METHODS

The medical records of patients who underwent cervical cerclage under spinal anesthesia using hyperbaric bupivacaine between March 2016 and May 2018 were retrospectively reviewed. The primary outcome measure was the correlation between gestational age and sensory block level of spinal anesthesia. Secondary outcomes included the correlations between gestational age and reduction in blood pressure and length of the postanesthesia care unit (PACU) stay. The Pearson correlation test, partial correlation test, and linear regression were used to identify relationships and to adjust for confounding variables.

RESULTS

Of the 261 cases reviewed, there was a linear and significant correlation between gestational age and sensory block level, reduction in systolic blood pressure during surgery, reduction in systolic blood pressure during PACU, and length of PACU stay, after adjusting for confounding factors (partial correlation coefficient=0.71, p<0.001; 0.27, p<0.001; 0.25, p<0.001; 0.21, p=0.001, respectively). A 1-day increase in gestational age corresponded to an increase of 0.04 dermatomes in sensory block level (95% CI 0.035 to 0.045, p<0.001).

CONCLUSION

Results demonstrated that as the gestational age progressed, sensory block level increased, blood pressure was decreased, and length of PACU stay increased after spinal anesthesia. Sensory block increased by 0.28 dermatomes when the pregnancy progressed 1 week. Further controlled prospective studies are needed to support this relationship.

TRIAL REGISTRATION NUMBER

KCT0000538.

Obstetric anesthesia: not just for cesareans and labor

The scope of obstetric anesthesia practice ranges far beyond the delivery of care to women for vaginal and cesarean deliveries. Increasingly, obstetric anesthesiologists are involved in the management of anesthetics for new procedures and for new indications. Anesthesia is frequently needed for maternal procedures, as well as fetal procedures, and at varying times in the intrapartum period. Maternal-specific procedures include cerclage, external cephalic version (ECV), postpartum bilateral tubal ligation (BTL), and dilation and evacuation (D and E). Fetus-specific procedures include fetoscopic laser photocoagulation and ex-utero intrapartum treatment (EXIT). This review will not include discussion of the anesthetic management of non-obstetric surgery during pregnancy, such as appendectomy or cholecystectomy.

Comparison of spread of subarachnoid sensory block and incidence of hypotension in early and late second trimester of pregnancy

Background

Obstetric or non-obstetric surgery can be performed in pregnant women during the second trimester. We evaluated maximal sensory block level (MSBL), and other sensory block characteristics after spinal anesthesia in early and late second trimester pregnant women.

Methods

Forty-four pregnant women scheduled for cervical cerclage under spinal anesthesia in the early second trimester (Group E) or in the late second trimester (Group L) were enrolled in this study. Spinal anesthesia was performed at the L3/4 and 7 mg of 0.5% hyperbaric bupivacaine was injected into the subarachnoid space. Hemodynamic variables, incidence of nausea/vomiting, ephedrine dose, and sensory block were recorded every 2.5 min during the first 15 min and 20 min after the injection. The MSBL, the time at which MSBL was achieved, and the time to the two-segment regression of the sensory level were also recorded.

Results

The maximum number of segments blocked was significantly greater in the Group L than in the Group E. The incidence of nausea/vomiting and hypotension, and dose of administrated ephedrine were significantly higher in the Group L than in the Group E. The mean arterial pressure during the 15 min after subarachnoid injection was significantly lower compared to the baseline value in the Group L.

Conclusions

The MSBL of spinal anesthesia with hyperbaric bupivacaine 7 mg were T9 in the early and T5 in the late second trimester groups. Pregnant women in the late second trimester exhibited increased incidence of hypotension and need for ephedrine than women in the early second trimester.