Phenylephrine boluses vs continuous infusion for preventing post spinal hypotension in low risk parturients undergoing elective caesarean section- A prospective observational study

Hypotension remains the most common complication following spinal anaesthesia, potentially leading to adverse maternal and foetal outcomes. Intravenous vasopressors such as Phenylephrine, Ephedrine and Mephenteramine are widely used to manage this. Prospective observational study at Al- Azhar Medical College and Superspecialty Hospital with a duration of 6 months. Study population include low risk parturients undergoing elective caesarean section. Sample size is 90.The study will be started after getting permission. Informed consent will be obtained from the patient prior to study participation. Patients will be divided into two groups A and B. Group A includes patients receiving Phenylephrine continous infusion. Group B includes patients receiving Phenylephrine intermittent boluses.All patients in our study undergoing caesarean section will be receiving spinal anaesthesia in sitting position using 25G whitacre/ Quincke needle. The drug administered intrathecally will be 0.5% Bupivacaine Heavy 2.2 mls. A sensory level of T5 will be ensured before the start of surgery. Group A will receive iv continuous infusion of phenylephrine at 0.5-0.6mcg/kg/min started immediately after spinal anesthesia and continued until Pitocin bolus is given after baby delivery. BP will be measured every minute.iv bolus of 50 mcgphenylephrine will be given if bp drops to less than 80 percentage of base line values. If HR falls below 50/min or if the SBP goes above 20% of baseline, the infusion of Phenylephrine will be held until it recovers. Patients in Group B will receive intermittent boluses of Phenylephrine 25 mcg iv every 3rd minute after spinal anaesthesia and this will be continued until Pitocin bolus is given after baby delivery and BP will be recorded every minute. iv bolus of 50 mcg phenylephrine will be givenwhen bp falls less than 80% baseline. If HR falls below 50/min or if the SBP goes above 20% of baseline, the next dose of intermittent bolus will be held until it recovers. After 1 minute of spinal anesthesia, heart rate, SBP and DBP are recorded every minute until baby delivery. After baby delivery, apgar score will be measured at 1 minute and 5 minutes.Primary outcome isIncidence of hypotension during the procedure (BP drops to less than 80 percentage of base line).Secondary outcomes is maternal and fetal complications , adverse effects of phenylephrine, maternal satisfaction and recovery time