Key result
A 1.66 mg dose of spinal bupivacaine resulted in significantly fewer hypotensive episodes at 10 minutes compared to a 2.5 mg dose (18.4% vs 42.2%, p=0.019) while providing equivalent labor analgesia.
Why the study?
Maternal hypotension and fetal bradycardia complicate combined spinal epidural, prompting evaluation of which spinal bupivacaine dose provides optimal analgesia with minimal side effects.
Does a lower dose of spinal bupivacaine (1.25 mg or 1.66 mg) reduce maternal hypotension and fetal bradycardia compared to 2.5 mg in parturients undergoing combined spinal epidural for labor analgesia?
RCT (n=159)
Double-blind
Machine level (daily fixed dose)
No
Does a lower dose of spinal bupivacaine (1.25 mg or 1.66 mg) reduce maternal hypotension and fetal bradycardia compared to 2.5 mg in parturients undergoing combined spinal epidural for labor analgesia?
Absolute Event Rate: 18.4% vs 42.2%
p-value: p=0.019
Lower doses of spinal bupivacaine (1.25 mg and 1.66 mg) combined with fentanyl provide equivalent labor analgesia to 2.5 mg while significantly reducing the incidence of maternal hypotension.
1.66 mg bupivacaine reduces hypotensive episodes versus 2.5 mg with equivalent analgesia; supports lower-dose CSE optimization in labor.
Study Objectives: Maternal hypotension and fetal bradycardia (FB) are recognized complications of combined spinal epidural. Our purpose was to ascertain which of 3 common doses of spinal bupivacaine results in optimal analgesia with minimal side effects, assuming the lowest dose fills all criteria. Design: Prospective, randomized clinical trial. Setting: Labor and Delivery Unit of 514-bed urban teaching hospital. Patients, Interventions and Measurements: Patients were assigned to receive an intrathecal dose of 20 mcg of fentanyl with either 2.5 mg, 1.66 mg, or 1.25 mg of isobaric bupivacaine. Visual Analog Scale (VAS) Pain Score, fetal heart rate (FHR), maternal blood pressure (BP), number of hypotensive episodes, doses of vasopressors, nitroglycerin and mode of delivery were recorded at various time points. Main results: 164 patients were enrolled: 66 receiving 1.25 mg, 50 in the 1.66 mg group and 48 in the 2.5 mg. At 6 and 10 minutes, we recorded in the 1.66 mg group: 4.7% and 4.6%, 18.9% and 23.9% fewer hypotensive episodes compared with the 1.25 mg and the 2.5 mg groups respectively and significantly more hypotensive episodes in the 2.5 mg group (p = 0.025 and 0.019 respectively). There was no statistical difference in vasopressors use, mode of delivery or FB. The VAS decreased equally by an average of 7–10 points among all groups. Conclusion: The 1.66 mg spinal dose was associated with the least hypotensive episodes and equivalent pain relief as the 2.5 mg. The 1.25 mg and 1.66 mg doses allowed for adequate BP and FHR stability. Clinical Trial: Study registered on the ClinicalTrial.gov website under the NCT number NCT02159807.
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Orlando et al. (2023) conducted an RCT in Labor pain (n=159). Spinal bupivacaine vs. 2.5 mg spinal bupivacaine (with 20 mcg fentanyl) was evaluated on Hypotensive episodes at 10 minutes (p=0.019). A 1.66 mg dose of spinal bupivacaine resulted in significantly fewer hypotensive episodes at 10 minutes compared to a 2.5 mg dose (18.4% vs 42.2%, p=0.019) while providing equivalent labor analgesia.