196 - Impact of low dose dexamethasone for lung disease in preterm infants on ductal shunting and cardiac indices: A prospective echocardiographic study

Poster Number: 196
Publication Number: 196.219

Arvind Sehgal, Monash Children’s Hospital, Melbourne, Victoria, Australia; Calum T. Roberts, Monash University, Melbourne, Victoria, Australia; Marcel Nold, Monash University, Melbourne, Victoria, Australia; Samuel Menahem, Monash University, Caulfield North, Victoria, Australia

Background: Corticosteroid therapy dexamethasone (DEX) is frequently used in preterm infants’ to facilitate extubation or reduce respiratory support requirements. Effects of DEX on cardiac indices have not been studied systematically. Literature from studies using larger dosages has exclusively focussed on the ‘systemic’ constructs such as left ventricular (LV) hypertrophy and elevated blood pressure (BP).

Objective: To ascertain the impact of first course DEX on ductal and cardiac indices when administered to preterm infants for lung disease.

Design/Methods: Preterm infants administered DEX were prospectively studied by pre-post echocardiography (ECHO 1&2), before and within 24 hours after DEX therapy. Parameters studied included ductal indices, measures of pulmonary vascular resistance (PVR), right ventricular systolic performance, fractional shortening and septal/free wall thickening and LV mass. ECHO data was indexed to body surface area (BSA) and cumulative DEX dose. DEX was adminstered per DART regimen.

Results: Thirty preterm infants with gestational age and birthweight 24.6±1.1 weeks and 612±125g respectively, were studied. The age at DEX administration was (median [interquartile range, IQR]) 16.5 (14, 24) days. Oxygen requirements improved significantly, median [IQR], (68% [52, 91] vs 30 [27, 40], p < 0.001). A patent ductus arteriosus was noted in 20 infants at ECHO1, the trans-ductal diameter reduced form 2.16±0.8 vs 1.1±0.8mm, p=0.0003. Complete closure was noted in 7/20 (35%) infants at ECHO2. Significant reduction in left pulmonary artery end-diastolic velocity was noted, (median [IQR], 26 [22, 29] vs 19 [0, 20], p < 0.001). PVR decreased (increased time to peak velocity/ right ventricular ejection time ratio, median [IQR], 0.21 [0.17, 0.22] vs 0.23 [0.21, 0.27], p=0.0001) and right ventricular systolic performance improved (Tricuspid Annular Plane Systolic Excursion, 4.9±0.8 vs 5.5±0.9 mm, p=0.02). No significant changes in fractional shortening, myocardial wall or septal thickness or LV mass were noted including after indexing for BSA or cumulative DEX. Significant ventriculo-arterial coupling between right ventricular systolic performance and measures of PVR was noted (r= 0.43, p=0.018). No signficant correlation was noted between 'change' in ECHO parameters to cumulative DEX dose. A significant though transient rise in systolic BP was noted.Conclusion(s): Low dose DEX, alongside improving respiratory status, significantly influences cardiovascular parameters related to the pulmonary circulation. Systemic effects were noted in the form of higher BP but no effect on LV morphology was detected.
Demographic and clinical data of the study cohortData presented as *median (interquartile range), rest data as mean ± standard deviation
^high frequency oscillation in 16/28 (57%), MAP-mean airway pressure,
^^four infants could not be extubated and two were already on non-invasive ventilation
at start of steroids
Comparison of echocardiographic (ECHO) parameters after dexamethasone (DEX) therapy (n=30).*median (interquartile range)