Vasopressors for the Treatment and Prophylaxis of Spinal Induced Hypotension during Caesarean Section.

Vasopressors have currently become the mainstay therapy for the management of spinal-induced hypotension (SIH) as the major mechanism of hypotension after spinal anaesthesia is the loss of arteriolar tone produced by sympathetic block. Vasopressors for the prophylaxis and treatment of SIH have been the subject of a significant amount of research, yet remain an attractive and important clinical problem. This review will highlight controversies and recent research on the use of vasopressors for both prophylaxis and treatment of SIH. For decades, ephedrine was considered to be the best vasopressor for the management of maternal hypotension. However, its use has been reported to be associated with a 5-fold increased risk of foetal acidosis than phenylephrine. At present, phenylephrine is the vasopressor of choice for preventing and treating SIH at caesarean section. However, its use is often associated with a decreased heart rate and low cardiac output state owing to the lack of β-mimetic activity. Norepinephrine has been introduced as an alternative vasopressor for preventing and treating SIH because of its additional β-mimetic activity. However before its routine clinical use, a further series of studies are needed to establish its efficacy and safety for both the mother and foetus.