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Very low birthweight (VLBW) infants, who weigh less than 3.3 pounds, are vulnerable to hypotension (very low blood pressure) and its associated clinical complications, such as intraventricular hemorrhage (IVH). Neonatal intensive care units (NICUs) often use vasopressor medications to raise blood pressure and increase cardiac contractility among hypotensive infants.
Despite the potentially severe consequences of low blood pressure, no widely accepted neonatal blood pressure standard has been defined. A new study that was supported by the Agency for Healthcare Research and Quality (HS07015) found that six NICUs in Massachusetts and Rhode Island cared for VLBW babies with varied prevalence of hypotension and hypertension and differed in their use of vasopressors to stabilize these infants.
The researchers evaluated differences in the prevalence of hypotension and hypertension among 1,288 VLBW infants admitted to six NICUs as part of an ongoing study of variations in outcomes of VLBW newborns. They recorded the lowest and highest mean blood pressures within the first 12 hours and the use of vasopressors within the first 24 hours of NICU admission, as well as the occurrence of IVH.
Two of the six NICUs had significantly higher percentages of infants with at least one hypotensive blood pressure, with prevalences of 24 to 45 percent. Hypotensive infants were significantly smaller, younger, and sicker than other infants. NICUs varied nine-fold in their use of vasopressors to treat infants, ranging from 4 percent at one NICU to 39 percent at another, a range that could not be explained by inter-NICU differences in birthweight, illness severity, or rates of hypotension. This may reflect specific NICU preferences for proactive versus reactive strategies (that is, treating before rather than after development of hypotension). Finally, the researchers found a borderline association between severe IVH and hypotension but not between severe IVH and hypertension.
See "Variations in prevalence of hypotension, hypertension, and vasopressor use in NICUs," by Issa Al-Aweel, B.S., DeWayne M. Pursley, M.D., M.P.H., Lewis P. Rubin, M.D., and others, in the Journal of Perinatology 21, pp. 272-278, 2001.
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