A Randomized Controlled Trial of Intrathecal 1% Chloroprocaine Versus 0.75% Hyperbaric Bupivacaine for Short Obstetric Procedures.

Background Intrathecal bupivacaine is commonly used for short obstetric procedures, including transvaginal cerclage placement, external cephalic version, and postpartum bilateral tubal ligation, despite evidence that chloroprocaine is associated with earlier postanesthesia care unit discharge after ambulatory surgery. We hypothesized that intrathecal chloroprocaine would shorten the duration of motor block after short obstetric procedures. Methods Single-center, randomized trial equally assigning 50 participants undergoing transvaginal cerclage placement, external cephalic version, or postpartum bilateral tubal ligation to 50 mg of 1% chloroprocaine or 10.5 mg of 0.75% hyperbaric bupivacaine. The primary endpoint was duration of motor block, defined by the count of assessments at five-minute intervals from study drug administration to knee flexion. Secondary endpoints included time to postanesthesia care unit discharge readiness, time to first ambulation, and rescue bladder catheterization. The study included an a priori halting rule to terminate if two chloroprocaine subjects failed to complete surgery under spinal anesthesia. Results The study was terminated at 27 subjects when a second spinal failure occurred in the chloroprocaine arm amongst patients undergoing tubal ligation surgery. Chloroprocaine was associated with decreased count of five-minute assessments until knee flexion (mean difference=7.6, 95% CI=2.9, 12.4; P=0.003), shorter time to postanesthesia care unit discharge readiness (mean difference=36.8 min, 95% CI=15.6, 58.0; P=0.001), and shorter time to first ambulation (mean difference 157 min, 95% CI=94.7, 219.3; P<0.001). Bupivacaine, relative to chloroprocaine, was associated with a 3.8-fold increased risk (95% CI=1.4, NA; P=0.02) of rescue bladder catheterization. Conclusion When utilized for transvaginal cerclage placement and external cephalic version, intrathecal chloroprocaine may shorten motor block, time to postanesthesia care unit discharge readiness, time to first ambulation, and reduce the frequency of bladder catheterization. Administration of 50 mg of 1% chloroprocaine intrathecally does not provide adequate anesthesia for bilateral tubal ligation surgery.