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

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.