DOSE REQUIREMENT OF INTRATHECAL BUPIVACAINE FOR CESAREAN DELIVERY IS SIMILAR IN OBESE AND NORMAL WEIGHT WOMEN Dose Requirement of Intrathecal Bupivacaine for Cesarean Delivery Is Similar in Obese and Normal Weight Women

The number of obese parturients seen in the practice of obstetric anesthesia is steadily increasing. Many of these women deliver by cesarean delivery under spinal anesthesia. The effect of weight and body mass index (BMI) on the spread of intrathecally administered local anesthetics is controversial. There are a limited number of studies that have correlated the weight or BMI with the spread of intrathecal local anesthetics. The majority of them investigated nonpregnant patients, and demonstrated conflicting results 1-3. In the obstetrical population, no correlation between the level of sensory block and the BMI has been found in term women undergoing cesarean delivery when fixed doses of hyperbaric bupivacaine were given 4,5. To our knowledge, there is no dose-response study of intrathecal hyperbaric bupivacaine comparing obese and normal-weight patients. The purpose of this study was to establish the effective dose 95% (ED95) of 0.75% hyperbaric bupivacaine co-administered with fentanyl and morphine for spinal anesthesia for elective cesarean delivery in obese and non-obese women. We hypothesized that obese and normal weight women would require the same dose of bupivacaine.