Techniques for preventing hypotension during spinal anaesthesia for caesarean section

Cyna AM, Andrew M, Emmett RS, Middleton P, Simmons SW

Published Online:

November 10, 2010

The incidence of hypotension during spinal anaesthesia for caesarean section is reduced by administering intravenous fluids, the drugs ephedrine or phenylephrine, or by leg compression.

Spinal anaesthesia is commonly used for caesarean section. Advantages for the mother include remaining awake for the birth, avoiding risks of general anaesthesia and facilitating effective postoperative pain relief. The commonest side-effect of spinal anaesthesia is hypotension, which is often accompanied by nausea or vomiting, or both. Severe hypotension poses serious risks to mother (such as loss of consciousness) and baby (such as lack of oxygen and brain damage). The review of 75 trials (4624 women) found that no single method completely prevents hypotension, but the incidence is reduced by administering intravenous fluids, the drugs ephedrine or phenylephrine, and by compressing the legs with bandages, stockings or inflatable boots.

Abstract (click to read)

Background:

Maternal hypotension, the most frequent complication of spinal anaesthesia for caesarean section, can be associated with severe nausea or vomiting which can pose serious risks to the mother (unconsciousness, pulmonary aspiration) and baby (hypoxia, acidosis and neurological injury).

Objectives:

To assess the effects of prophylactic interventions for hypotension following spinal anaesthesia for caesarean section.

Search strategy:

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2005). We updated this search on 30 June 2010 and added the results to the awaiting classification section of the review.

Selection criteria:

Randomised controlled trials comparing interventions to prevent hypotension with placebo or alternative treatment in women having spinal anaesthesia for caesarean section.

Data collection and analysis:

Three review authors independently assessed eligibility and methodological quality of studies, and extracted data.

Main results:

We included 75 trials (a total of 4624 women). Crystalloids were more effective than no fluids (relative risk (RR) 0.78, 95% confidence interval (CI) 0.60 to 1.00; one trial, 140 women, sequential analysis) and colloids were more effective than crystalloids (RR 0.68, 95% CI 0.52 to 0.89; 11 trials, 698 women) in preventing hypotension following spinal anaesthesia at caesarean section. No differences were detected for different doses, rates or methods of administering colloids or crystalloids. Ephedrine was significantly more effective than control (RR 0.51, 95% CI 0.33 to 0.78; seven trials, 470 women) or crystalloid (RR 0.70, 95% CI 0.50 to 0.96; four trials, 293 women) in preventing hypotension. No significant differences in hypotension were seen between ephedrine and phenylephrine (RR 0.95, 95% CI 0.37 to 2.44; three trials, 97 women) and phenylephrine was more effective than controls (RR 0.27, 95% CI 0.16 to 0.45; two trials, 110 women). High rates or doses of ephedrine may increase hypertension and tachycardia incidence. Lower limb compression was more effective than control (no leg compression) (RR 0.69, 95% CI 0.53 to 0.90; seven trials, 399 women) in preventing hypotension, although different methods of compression appeared to vary in their effectiveness. No other comparisons between different physical methods such as position were shown to be effective, but these trials were often small and thus underpowered to detect true effects should they exist.

Authors' conclusions:

While interventions such as colloids, ephedrine, phenylephrine or lower leg compression can reduce the incidence of hypotension, none have been shown to eliminate the need to treat maternal hypotension during spinal anaesthesia for caesarean section. No conclusions can be drawn regarding rare adverse effects due to the relatively small numbers of women studied.

[Note: The 89 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

This record should be cited as:

Cyna AM, Andrew M, Emmett RS, Middleton P, Simmons SW. Techniques for preventing hypotension during spinal anaesthesia for caesarean section. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD002251. DOI: 10.1002/14651858.CD002251.pub2

Assessed as up to date:

June 6, 2006

Find the research

Get full text at The Cochrane Library

Primary Review Group:

Pregnancy and Childbirth Group

Health topics:

Pregnancy & childbirth > Caesarian section > Anaesthesia

Cochrane Summaries^beta

Independent high-quality evidence for health care decision making

Techniques for preventing hypotension during spinal anaesthesia for caesarean section

More like this

Copyright © 2012 - The Cochrane Collaboration