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BackgroundExtreme preterm birth confers risk of long-term impairments in lung function and exercise capacity. There are limited data on the factors contributing to exercise limitation following extreme preterm birth. This study examined respiratory mechanics and ventilatory response during exercise in a large cohort of children born extremely preterm (EP).MethodsThis cohort study included children 8–12 years of age who were born EP (≤28 weeks gestation) between 1997 and 2004 and treated in a large regionalised neonatal intensive care unit in western Canada. EP children were divided into no/mild bronchopulmonary dysplasia (BPD) (ie, supplementary oxygen or ventilation ceased before 36 weeks gestational age; n=53) and moderate/severe BPD (ie, continued supplementary oxygen or ventilation at 36 weeks gestational age; n=50). Age-matched control children (n=65) were born at full term. All children attempted lung function and cardiopulmonary exercise testing measurements.ResultsCompared with control children, EP children had lower airway flows and diffusion capacity but preserved total lung capacity. Children with moderate/severe BPD had evidence of gas trapping relative to other groups. The mean difference in exercise capacity (as measured by oxygen uptake (VO2)% predicted) in children with moderate/severe BPD was −18±5% and −14±5.0% below children with no/mild BPD and control children, respectively. Children with moderate/severe BPD demonstrated a potentiated ventilatory response and greater prevalence of expiratory flow limitation during exercise compared with other groups. Resting lung function did not correlate with exercise capacity.ConclusionsExpiratory flow limitation and an exaggerated ventilatory response contribute to respiratory limitation to exercise in children born EP with moderate/severe BPD.

Background: Despite being an experimental therapy in preterm neonates, inhaled nitric oxide (iNO) is used as a rescue therapy when high-frequency oscillatory ventilation (HFOV) and other conventional therapies fail. Objective: We aimed to determine the outcomes of very-low-birth-weight (VLBW) neonates with hypoxemic respiratory failure (HRF) who had received iNO after maximal conventional therapies. Methods: We retrospectively reviewed preterm neonates (<33 weeks of gestation with a birth weight <1,500 g) who had all received HFOV and then iNO from March 1, 2009 to April 1, 2014 at the Royal Alexandra Hospital. We collected demographic and clinical parameters, doses, duration and response to iNO, survival to neonatal intensive care unit (NICU) discharge, major complications, and neurodevelopmental outcome at 18-24 months of corrected age. Results: During the study period, 1,168 eligible preterm neonates were admitted; 155 (13%) had HRF treated with HFOV, of whom 47 (30%) received iNO. The baseline characteristics between the 24 survivors and 23 nonsurvivors were not different. Survivors had a greater decrease in oxygenation index than nonsurvivors (61 vs. 33%) after 6 h of iNO (p = 0.003). The causes of death were refractory hypoxemia (8), multi-organ failure (7), treatment withdrawal (6), and others (2). During the NICU stay, 23 survivors (96%) developed complications. At 18-24 months, 7 (29%) had significant disabilities. Conclusions: Of the VLBW neonates with severe HRF rescued by HFOV and iNO, many survived without neurodevelopmental disability at early childhood, despite multiple short-term complications. Further research is necessary to understand the clinical course and risk factors of adverse outcomes and to improve the management care of these critically ill neonates.

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