046 - Can Echocardiographic Parameters Predict iNO Wean Success in Neonates with Acute Pulmonary Hypertension?

Publication Number: 46.4452

Piyawat Arichai, Children's Hospital Los Angeles, Pasadena, CA, United States; Srikumar Nair, Children's Hospital Los Angeles, Los Angeles, CA, United States; Julian E. Cameron, Children's Hospital Los Angeles, Los Angeles, CA, United States; Pierre Wong, Children's Hospital Los Angeles, Los Angeles, CA, United States; Shahab Noori, CHLA, USC, Los Angeles, CA, United States

Background: Echocardiography (ECHO) is the gold standard to confirm the diagnosis and evaluate response to therapy in acute pulmonary hypertension (aPH) in neonates. While some ECHO measures have been associated with clinical outcomes, ECHO correlation with successful weaning of inhaled nitric oxide (iNO) has not been reported.

Objective: To assess ECHO parameters of neonates with iNO wean failure compared to controls with successful iNO wean.

Design/Methods: This was a retrospective single-center study from January 1, 2013, to December 31, 2022, on neonates with aPH who received iNO and had iNO wean initiated within 30 days of life. Exclusion criteria included complex congenital heart disease, congenital diaphragmatic hernia, major congenital malformations, and extracorporeal membrane oxygenation. ECHO taken within 24 hours of wean initiation were evaluated for parameters related to pulmonary arterial pressure, pulmonary vascular resistance, myocardial performance, and interatrial and/or patent ductus arteriosus (PDA) shunting pattern. Demographics, diagnosis, medications, and oxygenation data were extracted from electronic medical record (EMR). Successful weaning from iNO was defined as the ability to reduce iNO without an increase in FiO₂ of more than 5% at each iNO level. Bivariate comparisons of clinical and ECHO parameters were conducted using chi-square, t-tests, and Wilcoxon Rank-Sum test as appropriate.

Results: Of 356 neonates screened, 104 were included in the study (Figure 1). Of these neonates, 86 (83%) successfully weaned off iNO, while 18 (17%) experienced weaning failure (Table 1). The median birth weight was lower in the failure group (2,800 vs 3,308 g, p=0.0275). The primary diagnosis was different between the two groups (p=0.043). No differences in pulmonary vasodilator use were observed. ECHO parameters, including ventricular septal geometry, eccentricity index, pulmonary artery flow profile, and shunt directionality, did not correlate with the outcome. Tricuspid regurgitation velocity trended higher in the failure group (383 vs 330 cm/s, p=0.115), and fractional shortening was lower in the failure group (38.7% vs 41.7%, p=0.147), but neither reached statistical significance.

Conclusion(s): In this retrospective study, we did not find associations between common ECHO parameters and successful iNO wean. Further analysis is needed to evaluate for other clinically significant outcome definitions, ECHO parameters, and adjust for confounders.

Figure 1: Flow Diagram of the Study Population
EMR – electronic medical record; ICD – International Classification of Diseases; CPT – Current Procedural Terminology; CHD – congenital heart disease; CDH – congenital diaphragmatic hernia; ECMO – extracorporeal membrane oxygenation

Table 1: Demographics and Echocardiographic Measurements by iNO Wean Outcomes
iNO – inhaled nitric oxide; MAS – meconium aspiration syndrome; HIE – hypoxic ischemic encephalopathy; RDS – respiratory distress syndrome; EI – eccentricity index; PDA – patent ductus arteriosus; PFO – patent foramen ovale; ASD – atrial septal defect; TRmax – Tricuspid regurgitation max velocity; LV FAC - Fractional area change (left ventricle); Fractional shortening (left ventricle); TAPSE - Tricuspid Annulus Plane Systolic Excursion