The Correlation between Body Mass Index and Vasopressor Need after Spinal Anaesthesia for Cesarean Section UC05-UC09
Dr. Eissa Bilehjani,
Daneshgah ave. no. 31, Tabriz, East Azerbaijan, Iran.
Introduction: Hypotension is one of the common complications of spinal anaesthesia in mothers undergoing cesarean delivery. Vasopressor such as ephedrine or phenylephrine are the most common drugs employed to treat hypotension induced by spinal anaesthesia. Obese women have a limited physiological reserve and usually show remarkably greater complications of pregnancy and anaesthesia.
Aim: To compare the requirement of vasopressor therapy for spinal anaesthesia-induced hypotension, between parturients with BMI =30 kg/m2 and those with BMI <30 kg/m2 in cesarean section.
Materials and Methods: The study population included 160 healthy singleton pregnant women aged between 18 and 40 years of age with term pregnancy who underwent elective cesarean section with spinal anaesthesia. Spinal anaesthesia was performed, using 10 mg of hyperbaric bupivacaine 0.5% plus 10 µg of fentanyl. Any fall of >20% in Mean Arterial Pressure (MAP) or reduction of systolic blood pressure below 100 mmHg was considered as hypotension; it was treated with intravascular fluid, ephedrine, or phenylephrine. At the end of the study, the participants were divided, based on their Body Mass Index (BMI), into normal and obese groups (BMI <30 kg/m2 or =30 kg/m2, respectively). Using SPSS statistical software, authors compared numbers of hypotension episode, need for vasopressor, and newborn status between the two groups.
Results: The mean±SD BMI of all patients was 33.24±5.73 kg/m2. In 51 mothers (31.9%), the BMI was below 30 kg/m2 and mean±SD BMI was 27.24±2.24 kg/m2. In 109 mothers (68.1%), the BMI was =30 kg/m2 and mean±SD BMI was 36.11±4.54 kg/m2. In 126 (79.7%) cases, the main indication for cesarean section was a previous experience of cesarean child-birth. Spinal anaesthesia failed in two cases (with BMI =30 kg/m2) and was changed to general anaesthesia. These mothers were excluded from the study, and the data were obtained from 158 cases. Intraoperative fluid requirement and blood loss were similar in normal and obese mothers. Hypotension rate was similar; however, in the majority of the cases, MAP was low in obese mothers. Ephedrine was administered more frequently and with high doses in obese mothers. Phenylephrine was employed in the similar manner. The newborn Apgar scores and umbilical cord acidosis rate were similar in both the groups.
Conclusion: It was found that the fall in arterial blood pressure was more severe in obese mothers after spinal anaesthesia. Vasopressor was required more frequently and in high doses in these obese mothers. Furthermore, a good newborn outcome can be delivered with appropriate haemodynamic management.