Can the passive leg raise test predict spinal hypotension during cesarean delivery? An observational pilot study

It was hypothesized that patients who are preload dependent, as demonstrated by a >12% increase in cardiac output in response to a passive leg raise test, would be more likely to exhibit hypotension during spinal anesthesia for cesarean delivery.

Cardiac output response to the passive leg raise test was measured in 40 women before spinal anesthesia with a noninvasive, continuous cardiac output monitor (NICOM®). Patients were divided into two groups based on their performance on the passive leg raise test; those who increased cardiac output >12% following passive leg raise test were considered fluid responsive. NICOM® hemodynamic values were collected from the onset of spinal anesthesia until 10min after delivery of the fetus. The incidence of hypotension, defined as mean arterial blood pressure <70% of the patient's baseline value was compared between the two groups. Vasopressor use, umbilical cord blood gases and Apgar scores were also compared between the groups.

Nine patients were fluid responsive and 31 were fluid non-responsive. The groups had similar demographics and baseline hemodynamic parameters. No significant differences were seen between the groups in the incidence of spinal hypotension, vasopressor use, or neonatal outcome. At the time of delivery, fluid responsive patients had larger cardiac outputs compared to fluid non-responsive patients.

In this pilot study, non-invasive assessment of the hemodynamic response to a volume load was not predictive of hypotension or vasopressor use during cesarean delivery under spinal anesthesia. Fluid responsiveness was related to hemodynamic responses at delivery.