Ventilatory responses to independent and combined hypoxia, hypercapnia and hypobaria in healthy pre-term-born adults.

Details

Ressource 1Download: 425. Narang JPhysiol23 Ventilatory responses independent combined hypoxia hypercapnia hypobaria Preterm.pdf (1977.95 [Ko])
State: Public
Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_3D11575E235F
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Ventilatory responses to independent and combined hypoxia, hypercapnia and hypobaria in healthy pre-term-born adults.
Journal
The Journal of physiology
Author(s)
Narang B.J., Manferdelli G., Bourdillon N., Millet G.P., Debevec T.
ISSN
1469-7793 (Electronic)
ISSN-L
0022-3751
Publication state
In Press
Peer-reviewed
Oui
Language
english
Notes
Publication types: Journal Article
Publication Status: aheadofprint
Abstract
Pre-term birth is associated with physiological sequelae that persist into adulthood. In particular, modulated ventilatory responsiveness to hypoxia and hypercapnia has been observed in this population. Whether pre-term birth per se causes these effects remains unclear. Therefore, we aimed to assess pulmonary ventilation and blood gases under various environmental conditions, comparing 17 healthy prematurely born individuals (mean ± SD; gestational age, 28 ± 2 weeks; age, 21 ± 4 years; peak oxygen uptake, 48.1 ± 11.2 ml kg <sup>-1</sup> min <sup>-1</sup> ) with 16 well-matched adults born at term (gestational age, 40 ± 1 weeks; age, 22 ± 2 years; peak oxygen uptake, 51.2 ± 7.7 ml kg <sup>-1</sup> min <sup>-1</sup> ). Participants were exposed to seven combinations of hypoxia/hypobaria (equivalent to ∼3375 m) and/or hypercapnia (3% CO <sub>2</sub> ), at rest for 6 min. Pulmonary ventilation, pulse oxygen saturation and the arterial partial pressures of O <sub>2</sub> and CO <sub>2</sub> were similar in pre-term and full-term individuals under all conditions. Higher ventilation in hypoxia compared to normoxia was only observed at terrestrial altitude, despite an equivalent (normobaric) hypoxic stimulus administered at sea level (0.138 ). Assessment of oscillations in key variables revealed that combined hypoxic hypercapnia induced greater underlying fluctuations in ventilation in pre-term individuals only. In general, higher pulse oxygen saturation fluctuations were observed with hypoxia, and lower fluctuations in end-tidal CO <sub>2</sub> with hypercapnia, despite similar ventilatory oscillations observed between conditions. These findings suggest that healthy prematurely born adults display similar overall ventilation to their term-born counterparts under various environmental stressors, but that combined ventilatory stimuli could induce an irregular underlying ventilatory pattern. Moreover, barometric pressure may be an important factor when assessing ventilatory responsiveness to moderate hypoxic stimuli. KEY POINTS: Evidence exists for unique pulmonary and respiratory function under hypoxic conditions in adult survivors of pre-term birth. Whether pre-term birth per se causes these differences requires a comparison of conventionally healthy prematurely born adults with an appropriately matched sample of term-born individuals. According to the present data, there is no difference between healthy pre-term and well-matched term-born individuals in the magnitude of pulmonary ventilation or arterial blood gases during independent and combined hypobaria, hypoxia and hypercapnia. Terrestrial altitude (hypobaria) was necessary to induce differences in ventilation between normoxia and a hypoxic stimulus equivalent to ∼3375 m of altitude. Furthermore, peak power in pulse oxygen saturation was similar between hypobaric normoxia and normobaric hypoxia. The observed similarities between groups suggest that ventilatory regulation under various environmental stimuli is not impaired by pre-term birth per se. Instead, an integrated combination of neonatal treatment strategies and cardiorespiratory fitness/disease status might underlie previously observed chemosensitivity impairments.
Keywords
altitude, chemosensitivity, hypercapnia, hypobaria, hypoxia, prematurity, ventilation
Pubmed
Open Access
Yes
Create date
09/10/2023 12:47
Last modification date
23/01/2024 7:14
Usage data