Short- and long-term consequences of hypotension in ELBW infants

Abstract

Background: Hypotension affects close to half of all ELBW infants, yet an agreement on its definition is still lacking. Despite the fact that neonatal hypotension may be a risk factor for neurologic impairment, there is a paucity of data on the impact of low blood pressure (BP) in extremely low birth weight (ELBW) infants weighing below 1000 g on neuro-developmental outcome.

Objectives: Explore the relationship between blood pressure in the first 72 hours of life, perinatal factors, morbidity, and mortality in ELBW infants. Compare neuro-sensory outcome in ELBW infants with and without symptomatic hypotension.

Methods: We reviewed the outcome for all 156 infants with a birth weight <1000 g admitted to the neonatal intensive care unit covering the time period 1998 to 1999. Infants who received fluid pushes and/or pressors during the first 72 hours of life in an attempt to increase blood pressure were regarded as "symptomatic" or "treated infants"; the others were designated "non-treated infants." Follow-up at 20 months corrected age included neurologic status, Bayley motor/mental evaluation, plus tests of vision and hearing. Statistical analysis was by SPSS 11.0. Univariate and multivariate analyses were conducted to determine morbidities associated with symptomatic hypotension.

Results: A total of 59 infants (mean BW 714 +/- 154 g; GA 24.9 +/- 1.7 weeks) required BP support; 97 infants (mean BW 768 +/- 141 g; GA 26.1 +/- 1.9 weeks) received no BP support. The groups had similar race, gender, delivery mode, and maternal socioeconomic status. Thirty-five (22%) infants died, including 20 who received BP support. There were more infants with severe IVH (grade III/IV), 19% versus 2%, and the mortality was greater, 34% versus 16%, in those infants who received BP support. Of the 121 survivors, 110 (91%) had complete follow-up evaluations. Multivariate analysis controlling for SES and neonatal morbidity revealed that symptomatic hypotension is associated with delayed motor development (-6.0; SE 3.1) and hearing loss (O.R. 8.9; CI 0.92-86.3).

Conclusions: Symptomatic hypotension in ELBW infants in the first 72 hours of life is associated with significant short-term and long-term morbidity. Infants with symptomatic hypotension are more likely to have delayed motor development, hearing loss, and death.