Variations in prevalence of hypotension, hypertension, and vasopressor use in NICUs.

Abstract

Very low birth weight infants are vulnerable to hypotension and its associated complications. Vasopressors are used to raise blood pressure (BP), but indications for use are uncertain. Our objectives were (1) to study variations in BP stability among NICUs, (2) to investigate inter-NICU differences in vasopressor use, and (3) to address the association between intraventricular hemorrhage (IVH) and abnormal BPs. A total of 1288 infants with birth weight <1500 g were admitted to six NICUs in Massachusetts and Rhode Island over 21 months. The lowest and highest mean BPs were collected within the first 12 hours. Also recorded were the use of vasopressors within the first 24 hours and the occurrence of IVH. Logistic regressions were used to model outcomes, controlling for gestational age and illness severity using the Score for Neonatal Acute Physiology. Two of the six NICUs had significantly higher percentages of infants with at least one hypotensive BP, with prevalences of 24% to 45%. Percentages of infants treated with vasopressors ranged from 4% to 39%. This range of vasopressor use could not be explained by inter-NICU differences in birth weight, illness severity, or rates of hypotension. We found a borderline association between severe IVH and hypotension (odds ratio 1.6, p=0.055), but not between severe IVH and hypertension. Wide differences exist in the prevalence of hypotension, hypertension, and vasopressor use among NICUs. We also found an association between hypotension and IVH, but not between hypertension and IVH.