Objectives: The aim of this study was to analyze the time course of cardiovascular effects in glucocorticoid-treated premature infants with bronchopulmonary dysplasia (BPD).
Methods: In a retrospective case study, 63 ventilator-dependent very-low-birth-weight neonates (mean gestational age = 27.9 +/- 2 weeks and mean birth weight = 920 +/- 275 g) treated with dexamethasone (52%) or betamethasone (48%) were studied. The average value for each study day was calculated for systolic arterial blood pressure and heart rate.
Results: At initiation of treatment, blood pressures increased significantly from pre-treatment to day 1 and continued to increase during the first week: as a percentage of pre-treatment baseline the mean increase for systolic arterial blood pressure was 19% (95% confidence interval [CI] = 16, 22) on day 2 (P < 0.001). The maximum amplitude of variation was observed before day 2 for 75% of the study group. As a group as a whole, the heart rate value significantly decreased on day 1 (mean difference = -14.6 beats/min; 95% CI = -16.5, -12.6; P < 0.001), and then reached pre-treatment value within one week. Cardiovascular response was independent of gestational age, birth weight and postnatal age at the beginning of treatment.
Conclusion: During postnatal steroid therapy a rise in blood pressure is a common side effect, but bradycardia is mentioned very occasionally. The present study shows a marked increase in blood pressure during the first 48 hours concomitant with a decrease in heart rate. The inverse relationship between systolic arterial blood pressure and heart rate suggests a baroreflex response.