Prophylactic Phenylephrine and Fluid Co-administration to Reduce Spinal Hypotension During Elective Caesarean Section in a Resource-limited Setting: a Prospective Alternating Intervention Study

Spinal anaesthesia is currently standard of care for patients undergoing caesarean section. Obstetric spinal hypotension is a common and important problem, related to important maternal and foetal outcomes. The prevention and treatment of spinal hypotension has been well researched in resource-rich settings, a context different from that encountered in the South African setting. It has been previously shown that a prophylactic phenylephrine infusion is effective in resource-limited settings, but this method is still dependent on the availability of an infusion pump.The ideal dose offering the best risk to benefit profile is 25 to 50 mcg/min. It has recently been shown that a prophylactic phenylephrine infusion, administered by an infusion pump, appears safe and effective in resource-constrained environments. However, some institutions in South Africa are limited by a lack of available infusion pumps. There is an urgent need to translate these research findings into a pragmatic management strategy that is safe and effective where this equipment is lacking. A 18g Jelco allows flow of approximately 100 ml/min in the absence of a pressure bag: therefore with 500 mcg in 1000 ml of ringers lactate and a fully opened line, a maximum dose of 50 mcg.min-1 will be achieved. If the rate is 50 ml/min (20 minutes for the first litre) the dose will be 25 mcg.min-1. This dose range will offer maximum benefit with low risk of side effects.

This exploratory study will establish if a phenylephrine (500 mcg) bolus, added to the first litre of Ringers lactate given as a co-load, is an effective and safe means to prevent post obstetric spinal hypotension. This regime will be compared to the existing South African national protocol of the management of obstetric spinal hypotension. The findings of this study will provide valuable information regarding a safe and potentially effective means to prevent obstetric spinal hypotension.