correlation of body mass index and spread of spinal block in herniorrhaphy patients under spinal anesthesia

Background: the level and time block in patients undergoing spinal anesthesia are affected by a variety of demographic factors (e.g., age, gender, height, weight, body mass index [bmi] and the amount of cerebrospinal fluid). although the influence of bmi in spinal anesthesia is still a matter of controversy, the aim of this study was to determine the relationship between bmi and time of spinal block anesthesia in herniorrhaphy patients.methods: one hundred and eighty patients, who had undergone an inguinal herniorrhaphy operation, were divided into two groups-obese (bmi ≥30kg/m²) and nonobese (bmi<30kg/m²). demographic characteristics, operation time, anesthesia time, time sensory and motor block and changes in hemodynamics were compared between the two groups. the evaluation of spinal block height was recorded with the help of a pinprick test and bromage scale after the administration of bupivacaine.results: body weight, height and bmi showed significant differences in the two groups and the time to reach sensory block t10 was significantly shorter in the group of obese patients. the time for recovery of sensory and motor block was longer in the obese group than in the nonobese group. moreover, there were differences in the pattern of blood pressure of the two groups during surgery.conclusion: the results of this study showed a correlation between bmi and the time of spinal block anesthesia. furthermore, the maximum motor and sensory block specified in obese patients happens faster and the analgesic duration could be prolonged in patients with a higher bmi.