280 - Inhaled Nitric Oxide for Very Preterm Infants with Late-onset Acute Pulmonary Hypertension Crisis: Results from the Prospective Canadian National Preterm iNO Registry

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 280
Publication Number: 280.341

Michelle Baczynski, Mount Sinai Hospital, Toronto, ON, Canada; Dany Weisz, University of Toronto Temerty Faculty of Medicine, Toronto, ON, Canada; Laura Thomas, Mount Sinai Hospital, Toronto, Toronto, ON, Canada; Stephanie Fevrier, Sunnybrook, Toronto, ON, Canada; Michael P. Castaldo, BC Women's Hospital and Health Centre, Vancouver, BC, Canada; Amuchou S. Soraisham, University of Calgary, Calgary, AB, Canada; Abbas Hyderi, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Rula Agarushi, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Soume Bhattacharya, The University of Western Ontario - Schulich School of Medicine & Dentistry, London, ON, Canada; Renjini Lalitha, The University of Western Ontario - Schulich School of Medicine & Dentistry, London, ON, Canada; Amneet Sidhu, McMaster University Michael G. DeGroote School of Medicine, Hamilton, ON, Canada; Muzafar Gani Abdul Wahab, McMaster University Michael G. DeGroote School of Medicine, Hamilton, ON, Canada; Gabriel Altit, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Audrey Hebert, Faculty of Medicine Université Laval, Quebec city, PQ, Canada; Deepak Louis, Max Rady College of Medicine, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, MB, Canada; Souvik Mitra, Dalhousie University & IWK Health, Halifax, NS, Canada; Poorva Deshpande, Mount SInai Hospital, Toronto, ON, Canada; Ashraf Kharrat, Mount Sinai Hospital, Toronto, ON, Canada; Faith Zhu, University of Toronto Temerty Faculty of Medicine, Toronto, ON, Canada; Joseph Ting, University of Alberta, Edmonton, AB, Canada; Eugene Woojin Yoon, Mount Sinai Hospital, Toronto, ON, Canada; Prakesh S. Shah, Mount Sinai Hospital, Toronto, ON, Canada; Amish Jain, University of Toronto Temerty Faculty of Medicine, toronto, ON, Canada; YASSER ELSAYED, University of Mnaitoba, Winnipeg, MB, Canada

Presenting Author(s)

Amish Jain, MD PhD (he/him/his)

Staff Neonatologist
University of Toronto Temerty Faculty of Medicine
toronto, Ontario, Canada

Co-Author(s)

MB

Michelle Baczynski, BSc RRT

Respiratory Therapy NICU Practice Resource
Mount Sinai Hospital
Toronto, Ontario, Canada

Background: Owing to protracted hospital stay, very preterm neonates (gestational age, GA < 32 weeks) are at risk of acute pulmonary hypertension (aPH) crisis occurring beyond the transitional period (late aPH, >72 hours after birth). While inhaled nitric oxide (iNO) is often instituted to improve oxygenation, there is paucity of data on its utility and subsequent outcomes.

Objective: To delineate clinical characteristics and outcomes of very preterm infants treated with iNO for late aPH episodes in Canadian tertiary neonatal intensive care units (NICUs) and examine factors associated with pre-discharge mortality.

Design/Methods: In this prospective observational cohort study conducted across 12 Canadian tertiary NICUs over 3 years, granular clinical data for very preterm neonates treated with iNO during hospital stay was collected. For this study, infants with treatment indication coded as late aPH by participating sites were included. Patients with congenital anomalies were excluded. Only the first late aPH episode/infant was included. Characteristics examined included demographics, given primary diagnosis, pre-iNO cardio-pulmonary illness severity, diagnosis confirmed on echocardiography (vs. presumed), iNO dose and positive response rate (defined as FiO₂ reduction ≥0.2 at 4 hours post-iNO), and outcomes. Neonates who survived to discharge were compared to those who died. Logistic regression analysis was conducted to identify factors associated with mortality, including variables selected a priori: GA, small for GA, sex, age at treatment, primary diagnosis, confirmed aPH, positive response to iNO, and additional variables identified on univariate analysis.

Results: A total of 116 neonates who received iNO for late aPH with a mean (SD) GA 25.0 (1.8) weeks and birth weight of 742 (221) grams, were included; 12 had >1 late aPH episode. Overall a positive response to iNO was classified in 39%. The cohort had a high mortality and morbidity rate (Table 1). On intergroup comparison, while both groups had high illness severity, those who died were relatively younger and had worse pre-iNO cardio-pulmonary illness severity (Table 2). On adjusted analysis, only pre-iNO FiO₂ and pH, and not response to iNO, were associated with mortality (Table 3).

Conclusion(s):

Late aPH crisis is associated with high mortality among very preterm neonates. While ~40% demonstrate improvement in FiO₂ after iNO, mortality is related to pre-treatment illness severity and not iNO responsiveness. Further research is required to identify underlying pathophysiology and effective therapies for late aPH in preterm neonates.