Cardiorespiratory adaptation to low-dose dexamethasone for lung disease in extremely preterm infants: A prospective echocardiographic study

The cardiovascular impact of dexamethasone (Dex) is not well understood. Most data are obtained from a 6 week, high-dose regimen, and are limited to findings of hypertension and cardiac hypertrophy. The present study ascertained the impact of low-dose Dex on cardiac indices when administered to extremely preterm infants for lung disease. A pre-post intervention prospective echocardiographic (Echo) study was undertaken, with cardiac assessments performed before and within 24 h after completion of first course of therapy (10 day regimen, cumulative 0.89 mg kg(-1)). Thirty infants with a gestational age of 24.6 +/- 1.1 weeks and birthweight of 612 +/- 125 g, respectively, were studied. The age at Dex administration was 20 +/- 9 days. Fractional inspired oxygen decreased from 0.7 +/- 0.23 to 0.35 +/- 0.14 (P < 0.001). Patent ductus arteriosus was noted in 20 infants at Echo1. At Echo2, the ductal diameter decreased from 2.16 +/- 0.8 to 1.1 +/- 0.8 mm (P = 0.0003), with complete closure in 7/20 (35%). A reduction in left pulmonary artery end-diastolic velocity was noted (17 +/- 12 to 9 +/- 10 cm s(-1), P < 0.001). Pulmonary vascular resistance decreased (increased time to peak velocity/right ventricular ejection time, 0.2 +/- 0.03 to 0.23 +/- 0.03, P = 0.0001) and right ventricular systolic performance improved (tricuspid annular plane systolic excursion, 4.9 +/- 0.8 to 5.5 +/- 0.9 mm, P = 0.02). No significant changes in fractional shortening and left ventricular mass were noted. A significant increase in blood pressure was noted. As a percentage of pre-treatment baseline, the mean increase for systolic blood pressure was 20.3% (95% confidence interval = 14-26) on day 2 (P = 0.008). Low-dose Dex influenced cardiovascular parameters related to pulmonary circulation. Key points center dot Corticosteroid therapy is frequently used in preterm infants who are dependent on ventilator support. center dot Echocardiographic studies in infants administered a 6 week course of steroids have noted left ventricular hypertrophy, outlet obstruction and hypertension, but no information is available on right heart indices. center dot The cardiopulmonary effects of the current, significantly lesser cumulative dose (10 day regimen, commonly described as 'DART') have not been evaluated. center dot The present study noted a significant influence on ductal and pulmonary circulation indices. Left heart architecture and function was maintained, whereas a significant but transient increase in blood pressure was noted.

Automated summary

This study investigated the impact of low-dose dexamethasone on cardiac indices in extremely preterm infants. The results showed that low-dose dexamethasone influenced cardiovascular parameters related to pulmonary circulation, such as ductal diameter and left pulmonary artery end-diastolic velocity. Left heart architecture and function were maintained, but there was a transient increase in blood pressure.