Khawaja Kamal Nasir, Erum Shahid, Arshad Saleem Shahani.
To compare the height of block during elective Cesarean Section in obstetric patients using hyperbaric and isobaric bupivacaine keeping the space and volume constant.
Ann Pak Inst Med Sci Jan ;1(3):146-9.

Background: Regional anesthesia is the technique of choice for caesarean section. Caesarean section requires a T4 sensory level block for optimum condition for surgery. Out of the regional techniques spinal anesthesia is more popular as compared to epidural anesthesia for various reasons. Bupivacaine is the drug most commonly employed to achieve spinal anesthesia. Bupivacaine is available in isobaric and hyperbaric forms. The height of block achieved after injection of the local anesthetic in the subarachnoid space depends mainly on the baricity of the local anesthetic employed. In this study we tried to observe the height of block achieved by using isobaric and hyperbaric bupivacaine in obstetric patients undergoing elective caesarean section keeping the space and volume constant. Methods: This study was conducted in maternal child health center of Pakistan institute of medical sciences. Sixty patients selected according to inclusion criteria were divided into two groups of 30 each. Patients were preloaded with 1000 milliliters of lactated ringer solution within ten minutes with a 16 G intravenous line prior to the injection of local anaesthetic in subarachnoid space. Standard monitoring was attached to the patients. Two milliliters of hyperbaric bupivacaine 0.75% was injected to group H patients and two milliliters of 0.5% isobaric bupivacaine was injected to group I patients. Patients were given supine position with ten-degree head tilt and left lateral table tilt. For the first 10 min the block was assessed after every two minutes by loss of temperature sensation to ice. Result: There was a statistically significant difference in the height of block achieved in the two groups, that is hyperbaric bupivacaine group and isobaric bupivacaine group (P value <0.05). Conclusion: The height of block achieved with hyperbaric bupivacaine is more reliable and predictable than isobaric bupivacaine, in obstetric patient scheduled for caesarean sections.

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