PREVENTING HYPOTENSION FOLLOWING SPINAL ANAESTHESIA FOR CAESAREAN SECTION

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AM Cyna, PF Middleton, RS Emmett, SW Simmons
Women's and Children's Hospital, Adelaide, SA

Purpose of Study

To assess the effects of interventions to prevent maternal hypotension following spinal anaesthesia for caesarean section.

Method

We used standard Cochrane Collaboration methodology, comprehensive searching (to November 2005), explicit selection criteria; independent data extraction and assessment of study quality; and a random effects model for meta-analyses.

Result

The 69 included RCTs compared various ways of preventing hypotension. Major comparisons were:

• Fluids (colloids and crystalloids 14 studies)
• Colloids were more effective than crystalloids in preventing hypotension (RR 0.69 95% CI 0.55, 0.86, n=903 women). No differences were seen for nausea and vomiting or neonatal Apgar scores at 5 minutes (five studies each); neonatal acidosis (two studies) or maternal cardiac dysrhythmia (one study).

Ephedrine and phenylephrine

Ephedrine was more effective than no ephedrine in preventing hypotension (RR 0.55 95% CI 0.37, 0.83; 10 studies, 590 women). No differences were seen for nausea and vomiting or neonatal Apgar scores at 5 minutes (seven studies each); neonatal acidosis (six studies) or maternal hypertension (RR 1.52 95% CI 0.91,2.53; five studies) Ephedrine was more effective than crystalloid in six studies. No differences in hypotension incidence was seen when ephedrine was compared with phenylephrine in four studies (RR 0.71 95% CI 0.48, 1.03). Higher doses of ephedrine (30 mg) prevent more cases of hypotension but may increase the incidence of hypertension.

Physical methods/positioning

Lower limb compression was more effective than control in preventing hypotension (RR 0.69 95% 0.53, 0.90; seven studies, 399 women).

Conclusion

Colloid or crystalloid preloading, parenteral ephedrine administration and lower limb compression (bandages, stockings or inflatable boots) effectively reduce the incidence of hypotension requiring intervention. No conclusions regarding adverse effects (e.g. maternal heart rate; fetal acidosis) of the studied interventions can be drawn, probably due to their low incidence, the small number of women studied, and incomplete data reported.

Time of Presentation
Sunday 14 May 2006 - 1030-1200