In a randomized double-blinded prospective study, the 1.66 mg dosage of Bupivacaine demonstrated the least number of hypotensive episodes while offering similar pain relief to the 2.5 mg dosage in parturients undergoing combined technique for labor analgesia. Barbara S. Orlando et al. aimed to determine the most effective dose of spinal Bupivacaine among the three commonly used doses, considering the lowest dose as the one that meets all criteria for optimal analgesia while minimizing adverse effects.

At various time points, the researchers noted the number of hypotensive episodes, maternal blood pressure, fetal heart rate, visual analog scale (VAS) pain score, doses of vasopressors, nitroglycerin, and mode of delivery for subjects who were given a 20 mcg intrathecal dosage of Fentanyl along with either 2.5 mg, 1.66 mg, or 1.25 mg of isobaric Bupivacaine. A total of 164 individuals were included in the study, with 66 patients in the 1.25 mg group, 50 patients in the 1.66 mg group, and 48 patients in the 2.5 mg group.

At the 6 and 10-minute marks, the 1.66 mg group had 4.7% and 4.6% fewer hypotensive episodes contrasted to the 1.25 mg group, and 18.9% and 23.9% fewer hypotensive episodes as opposed to the 2.5 mg group, respectively. On the other hand, the 2.5 mg group had a substantially higher number of hypotensive episodes. There were no statistically significant differences observed in the utilization of vasopressors, mode of delivery, or fetal bradycardia among the groups. Across all groups, VAS scores declined by an average of 7-10 points.

To achieve both effective analgesia and minimize complications, it is recommended to utilize lower doses of Bupivacaine (1.25 mg and 1.66 mg) in combination with 20 mcg of Fentanyl. Both the 1.25 mg and 1.66 mg doses maintained satisfactory stability in blood pressure and fetal heart rate. This research provides valuable insights for healthcare professionals in choosing the appropriate dose of spinal bupivacaine to enhance patient care during labor and delivery, ultimately reducing potential complications.