PMID: 17021466

Issn Print: 0952-7907

Publication Date: 2003/06/01


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Management of hypotension in obstetric anesthesia: is it time to rewrite the textbooks?

Ferne Sevarino

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Excerpt

Hypotension is one of the most common complications of regional anesthesia in obstetric patients. This hypotension, often defined as a decrease in systolic blood pressure of 20% or to less than 100 mmHg, is a result of decreased intravascular resistance and venous capacitance secondary to the pooling of blood in the lower extremities and abdomen. Its prophylaxis and treatment is primarily directed towards concern that hypotension may result in decreased uteroplacental perfusion, and thus a compromised fetus.
Traditional teaching [1,2] is that hypotension can be minimized or prevented by the administration of intravenous fluids, positioning of the patient using left uterine displacement, and by the prophylactic and therapeutic use of vasopressors, in particular ephedrine. The recommendation for the preferential use of ephedrine in this population is based on animal studies [3,4], which suggested a more selective constriction of systematic vessels with ephedrine than with metaraminol. Other research suggested that alpha-adrenergic agents reduce uteroplacental perfusion by increasing uterine vascular resistance [5]. Ephedrine, however, readily crosses the placenta and may cause fetal tachycardia, which may be misinterpreted as fetal distress.
To date, there have been hundreds of articles debating the type and amount of fluid preload, whether or not prophylactic vasopressor use is more efficacious than therapeutic use, and which vasopressor is the preferred agent in this setting. Of the three ‘traditionally taught’ measures, only the use of left uterine displacement appears to be a supported and accepted practice utilized by all obstetric anesthesiologists [6,7].

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