Breathing heliox reduces expiratory flow limitation and improves exercise performance in adult survivors of extreme preterm birth (882.4)

Abstract

Extreme preterm birth (<32 weeks gestational age) results in arrested development of the lung characterized by abnormal alveologenesis and pulmonary vasculogenesis causing obstructive lung disease that persists into adulthood. We have recently shown that adults with a history of extreme preterm birth (PRE) have reduced aerobic exercise capacity relative to full term controls (CONT) that is not explained by pulmonary gas exchange inefficiency during exercise. These PRE subjects also have significant exercise‐induced flow limitation (EIFL), which has been suggested to be associated with a reduction in exercise capacity in healthy humans and in COPD subjects. Therefore, we hypothesized that reducing EIFL by breathing heliox (21% O2, 79% He) would improve exercise performance. Both PRE (n = 4) and CONT (n = 4) subjects performed two cycle ergometer exercise tests to exhaustion at 80% of their maximum power output; one breathing room air and one breathing heliox. Measurements breathing heliox were compared to those breathing room air at iso‐time. Flow‐volume loops were measured at rest and during both exercise tests to quantify EIFL. EIFL significantly decreased in PRE from room air (57% of tidal volume; VT) to heliox (9% VT), while CONT did not exhibit EIFL in either condition. Time to exhaustion significantly increased in PRE (38%), but not CONT (9%), breathing heliox compared to room air. These data suggest that excessive EIFL, may lead to an excessive work of breathing and/or mechanical constraints to increasing tidal volume during exercise, thereby significantly limiting exercise performance in PRE subjects.Grant Funding Source: Supported by AHA Scientist Development Grant and OHSU Early Clinical Investigator Grant