The use of vasopressors during spinal anaesthesia for caesarean section.

PURPOSE OF REVIEW: Hypotension remains one of the most researched subjects in obstetric anaesthesia. The purpose of this study is to review the most recent published articles on the use of vasopressors during spinal anaesthesia for caesarean section.

RECENT FINDINGS: Despite continued research indicating advantages of phenylephrine over ephedrine, practitioners in some countries continue to favour ephedrine. Recent research has continued to compare the two drugs with some work emerging on high-risk patients. Concern about reflexive bradycardia during phenylephrine use has led to consideration of alternatives. Norepinephrine which has mild β-adrenergic activity has been shown to have equivalent pressor activity but with less depressant effect on heart rate and cardiac output versus phenylephrine. Research continues to focus on methods of vasopressor administration. Prophylactic infusions of phenylephrine have been shown to be effective and may require less physician intervention compared with intermittent boluses. Automated computer-controlled systems have been further investigated using multiple agents and continuous noninvasive blood pressure monitoring.

SUMMARY: Evidence continues to support phenylephrine as the first-line vasopressor in obstetrics. However, recent research is emerging to suggest that low-dose norepinephrine may be a better alternative. Prophylactic infusions are effective and automated systems have potential for the future.