Abstract
Background: The hypoxic ventilatory response of individuals born prematurely appears blunted, sometimes leading to life-threatening conditions such as pulmonary oedema. It has already been shown (healthy subjects), that infra-clinical pulmonary oedema may rapidly appear in hypoxic conditions, especially after exercise and in real altitude. Our study was aimed to explore interstitial lung water accumulation during exercise in hypoxia (both hypobaric and normobaric) in a population of young adults born preterm.
Methods: Subjects underwent two sessions of 8 hours hypoxic exposure: The first one was conducted in normobaric hypoxia (NH; simulated altitude of 3840 m in hypoxic chamber, Planica, Slovenia), and the second one in hypobaric hypoxia (HH; real altitude of 3840 m, Aiguille du midi, Chamonix, France). Extravascular lung water (EVLW) was assessed by quantification of B-Lines (using LUS) at baseline, and before (Pre) and after (Post) exercise performed at 4 (H4) and 8 hours (H8) of hypoxic exposure.
Results: Eighteen and 16 subjects respectively performed the NH and HH evaluation. Neither baseline nor H4 evaluations showed any difference in the count of B-lines between NH and HH. Pre-H8 score was 2.0 ±1.1 in NH and 2.4 ±1.0 in HH (p=NS) while Post-H8 score was higher in HH (4.6 ± 1.6) than in NH (3.1 ± 1.4; p=0.0073). There were more subjects with a Post-H8 score of ≥5 B-lines in HH (7/16) than in NH (3/18; p=0.042).
Conclusions: In a population of adults born preterm, exercise induced a significant increase of lung B-lines after 8 hours of exposure in real altitude (HH) but not in simulated altitude of 3840 m. It suggests that HH is a more severe stimulus than NH.
- Copyright ©the authors 2017