Intrathecal 2-Chloroprocaine 3% Versus Hyperbaric Bupivacaine 0.75% for Cervical Cerclage: A Double-Blind Randomized Controlled Trial

A narrative review of the literature relevant to obstetric anesthesiologists: the 2023 Gerard W. Ostheimer lecture

This narrative review of the 2023 Gerard W. Ostheimer lecture presented at the Society for Obstetric Anesthesia and Perinatology 2023 annual meeting summarizes 2022 literature relevant to obstetric anesthesiologists.

ANTENATAL STUDIES

Neonatal morbidity is reduced with antenatal maternal buprenorphine compared with methadone for treatment of opioid use disorder. Antenatal pregnancy allergy testing is safe and feasible.

ANALGESIA AND ANESTHESIA STUDIES

Intrathecal (IT) 3% chloroprocaine for cervical cerclage results in faster sensory block resolution and discharge readiness compared with bupivacaine. The ED90 of 3% chloroprocaine (with IT fentanyl 10 µg) is 49.5 mg. Dural puncture epidural technique does not improve the quality of labor analgesia in obese parturients compared with epidural analgesia. Low- (>0.08 to ≤0.1%) and ultra-low (<0.08%) concentrations of bupivacaine for epidural analgesia maintenance result in similar maternal and neonatal outcomes. Lower doses of first line uterotonic agents are non-inferior to higher doses (oxytocin 0.5 IU vs. 5 IU and carbetocin 20 vs. 100 µg) in patients at low risk for postpartum hemorrhage. Supplemental analgesia or conversion to general anesthesia is necessary in approximately 15% of elective cesarean deliveries. Intravenous dexamethasone improves analgesia outcomes, however optimal dosing and timing remain unclear; it may induce neonatal hypoglycemia in the setting of gestational diabetes.

POSTPARTUM STUDIES

A core outcome set may help evaluate enhanced recovery protocol implementation. History of migraine and accidental dural puncture (ADP) above the L3 level are associated with epidural blood patch (EBP) failure and ADP at or below L3 and >48 h interval between ADP and EBP are associated with success.

Beta-blocker carteolol and oxprenolol produce cutaneous analgesia in response to needle pinpricks in the rat

BACKGROUND

This present study was undertaken to determine whether beta-blockers produce the cutaneous analgesic effect, comparing them with the long-acting local anesthetic bupivacaine.

METHODS

Using a rat model of infiltrative cutaneous analgesia, the effect of 5 beta-blockers (oxprenolol, carteolol, butaxamine, metoprolol, and acebutolol) and bupivacaine was compared and eventually combined with epinephrine.

RESULTS

Among 5 beta-blockers, oxprenolol exhibited the most potent and the longest duration of cutaneous analgesia. In dose-response studies, the rank order of efficacy (ED₅₀ [50% effective dose]) was bupivacaine (0.40 [0.35-0.47] μmol) > oxprenolol (2.33 [2.06-2.64] μmol) > carteolol (4.86 [4.27-5.53] μmol) (p< 0.01). Carteolol provoked a longer duration of analgesia (p< 0.01) than oxprenolol or bupivacaine on an equipotent basis (ED₂₅, ED₅₀, and ED₇₅). Adding epinephrine 1:200,000 to drug preparations (carteolol, oxprenolol, and bupivacaine) at ED₉₅ had a peripheral action in prolonging the duration of action.

CONCLUSIONS

Oxprenolol and carteolol had greater potencies and longer durations of cutaneous analgesia than butaxamine, metoprolol, and acebutolol. Oxprenolol produced a similar duration of action when compared to bupivacaine, while carteolol had a greater duration of action than bupivacaine. Cutaneous analgesia of oxprenolol (or carteolol) plus adrenaline was greater than that of bupivacaine plus adrenaline.

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.

Prenatal anesthetic exposure and offspring neurodevelopmental outcomes—A narrative review

While it is common for pregnant women to take anesthesia during surgery, the effects of prenatal anesthesia exposure (PAE) on the long-term neurodevelopment of the offspring remain to be clarified. Preclinical animal research has shown that in utero anesthetic exposure causes neurotoxicity in newborns, which is mainly characterized by histomorphological changes and altered learning and memory abilities. Regional birth cohort studies that are based on databases are currently the most convenient and popular types of clinical studies. Specialized questionnaires and scales are usually employed in these studies for the screening and diagnosis of neurodevelopmental disorders in the offspring. The time intervals between the intrauterine exposure and the onset of developmental outcomes often vary over several years and accommodate a large number of confounding factors, which have an even greater impact on the neurodevelopment of the offspring than prenatal anesthesia itself. This narrative review summarized the progress in prenatal anesthetic exposure and neurodevelopmental outcomes in the offspring from animal experimental research and clinical studies and provided a brief introduction to assess the neurodevelopment in children and potential confounding factors.

ED 90 of Intrathecal Chloroprocaine With Fentanyl for Prophylactic Cervical Cerclage: A Sequential Allocation Biased-Coin Design

BACKGROUND

Chloroprocaine is a short-acting local anesthetic that has been used for spinal anesthesia in outpatient surgery. There is limited experience with spinal chloroprocaine for prophylactic cervical cerclage placement. We sought to determine the effective dose of intrathecal chloroprocaine for 90% of patients (ED90) undergoing prophylactic cervical cerclage placement. We hypothesized that the ED90 of intrathecal chloroprocaine when combined with 10-ug fentanyl would be between 33 and 54 mg.

METHODS

In this prospective 2-center double-blinded study, we enrolled women undergoing prophylactic cervical cerclage placement under combined spinal-epidural anesthesia. A predetermined dose of intrathecal 3% chloroprocaine with fentanyl 10 ug was administered. The initial dose was 45-mg intrathecal chloroprocaine. Subsequent dose adjustments were determined based on the response of the previous subject using an up-down sequential allocation with a biased-coin design. A dose was considered effective if at least a T12 block was achieved, and there was no requirement for epidural activation or intraoperative analgesic supplementation during the procedure. The primary outcome was the ED90 of intrathecal chloroprocaine with fentanyl 10 ug. Secondary outcomes included duration of surgery, anesthetic side effects, time to resolution of motor and sensory block, time to achieve recovery room discharge criteria, and patient satisfaction with anesthetic care. Isotonic regression was used to estimate the ED90.

RESULTS

Forty-seven patients were enrolled into the study. Two patients were excluded (1 protocol violation and 1 failed block). In total, 45 patients completed the study. The estimated ED90 (95% confidence interval) for intrathecal chloroprocaine combined with fentanyl 10 ug was 49.5 mg (45.0-50.1 mg). The median (interquartile range [IQR]) duration of surgery was 15 (10-24) minutes. Resolution of the motor (Bromage 0) and sensory block took a median time of 60 (45-90) minutes and 90 (75-105) minutes, respectively. The median time to achieve recovery room discharge criteria was 150 (139-186) minutes. Satisfaction with anesthetic management was high in all patients. There were no reports of postdural puncture headache or transient neurological symptoms postoperatively.

CONCLUSIONS

The ED90 of intrathecal chloroprocaine combined with fentanyl 10 ug was 49.5 mg. Intrathecal chloroprocaine was associated with rapid block recovery and high patient satisfaction, which makes it well suited for outpatient obstetric procedures.