Anesthesia Complications During Scheduled Cesarean Delivery for Morbidly Obese Women

A number of studies have demonstrated that obesity increases the difficulty of placing regional anesthesia in nonpregnant women. Some investigators reported an increased need of conversion to general anesthesia during cesarean delivery among morbidly obese women, whereas others reported no difference in rates of regional anesthesia failure between obese and nonobese women. It is unclear whether the likelihood of regional anesthesia failure at nonemergent scheduled cesarean delivery is increased in morbidly obese women. The aim of this retrospective cohort study was to determine the incidence of complications of regional anesthesia among morbidly obese women undergoing scheduled cesarean delivery. Between 2004 and 2006, 578 singleton women undergoing scheduled cesarean delivery at an academic tertiary care center were identified using a perinatal database. The women included in the study were divided into the following 3 groups based on maternal pregravid body mass index (BMI): morbidly obese (BMI ≥40 kg/m2, n = 142), overweight and obese (BMI, 25–39 kg/m2, n = 251), and normal weight (BMI <25 kg/m2, n = 185). Receiver operating characteristic analyses were performed to determine factors predictive of composite regional anesthesia complications. The composite morbidity of anesthesia complications was the primary outcome measure. Complicated placement of regional anesthesia occurred in 5.8% of morbidly obese women, 2.8% of obese/overweight women, and none of the normal weight women (P < 0.001 for difference between morbidly obese and normal weight; the difference in complicated placement between the morbidly obese and obese/overweight groups was not significant [P = 0.17]). There were no anesthesia complications in the obese/overweight or the normal weight groups. In contrast, the following complications of anesthesia were found in the morbidly obese group: failure to establish a regional block (1.4%), insufficient duration of a regional block (2.8%), cephalad spread of regional block (1.4%), prolonged refractory severe hypotension (2.1%), and postdural puncture headache (0.7%); the overall rate of anesthetic complications in this group was 8.5%. All P values for comparison of complications between the morbidly obese and the other 2 groups were statistically significant (P < 0.05). Receiver operating characteristic curve analysis showed that prepregnancy BMI (area under the curve, 0.856) and delivery BMI (area under the curve, 0.877) were highly predictive of anesthesia complications. These findings show that, in comparison to lower-weight women, morbidly obese women undergoing scheduled cesarean delivery have significantly more anesthesia complications.