Hypotension and Adverse Outcomes in Prematurity: Comparing Definitions.

BACKGROUND

In the premature neonate, there is no consensus regarding normal blood pressure (BP). The most common definition used is a mean arterial BP (MAP) less than the gestational age (GA); however, studies indicate that the neuroprotective mechanism of autoregulation is lost below a MAP of 30 mm Hg.

OBJECTIVE

To determine whether hypotension defined as MAP <30 mm Hg or MAP less than the infant's GA better predicts adverse outcomes of intraventricular hemorrhage (IVH) and death.

STUDY DESIGN

For this retrospective study, demographic, clinical, and BP data in epochs of 12 h were collected during the first 72 h of life in 188 subjects 24-28 weeks of gestation. For each definition, outcomes of severe IVH (grade 3 or 4), death, or the composite outcome of either were evaluated using bivariate testing. Logistic regression determined independent predictors of composite outcome of death and/or grade 3 or 4 IVH.

RESULTS

Hypotension by either definition was significant for death and the composite outcome (p < 0.0001). Only the MAP <30 mm Hg definition was associated with severe IVH (p = 0.02). On logistic regression, significant predictors of the composite outcome were GA (OR 0.59, 95% CI 0.39-0.89) and vasopressor therapy (OR 5.5, 95% CI 2-17).

CONCLUSIONS

Neither definition of hypotension independently predicts adverse outcome in multivariate logistic regression. Vasopressor therapy, however, is an independent predictor of IVH and death in premature infants.