In:
Frontiers in Physiology, Frontiers Media SA, Vol. 14 ( 2023-10-10)
Abstract:
Introduction: This prospective cohort study assessed the effects of chronic hypoxaemia due to high-altitude residency on the cerebral tissue oxygenation (CTO) and cerebrovascular reactivity. Methods: Highlanders, born, raised, and currently living above 2,500 m, without cardiopulmonary disease, participated in a prospective cohort study from 2012 until 2017. The measurements were performed at 3,250 m. After 20 min of rest in supine position while breathing ambient air (FiO 2 0.21) or oxygen (FiO 2 1.0) in random order, guided hyperventilation followed under the corresponding gas mixture. Finger pulse oximetry (SpO 2 ) and cerebral near-infrared spectroscopy assessing CTO and change in cerebral haemoglobin concentration (cHb), a surrogate of cerebral blood volume changes and cerebrovascular reactivity, were applied. Arterial blood gases were obtained during ambient air breathing. Results: Fifty three highlanders, aged 50 ± 2 years, participated in 2017 and 2012. While breathing air in 2017 vs. 2012, P aO 2 was reduced, mean ± SE, 7.40 ± 0.13 vs. 7.84 ± 0.13 kPa; heart rate was increased 77 ± 1 vs. 70 ± 1 bpm ( p & lt; 0.05) but CTO remained unchanged, 67.2% ± 0.7% vs. 67.4% ± 0.7%. With oxygen, SpO 2 and CTO increased similarly in 2017 and 2012, by a mean (95% CI) of 8.3% (7.5–9.1) vs. 8.5% (7.7–9.3) in SpO 2 , and 5.5% (4.1–7.0) vs. 4.5% (3.0–6.0) in CTO, respectively. Hyperventilation resulted in less reduction of cHb in 2017 vs. 2012, mean difference (95% CI) in change with air 2.0 U/L (0.3–3.6); with oxygen, 2.1 U/L (0.5–3.7). Conclusion: Within 5 years, CTO in highlanders was preserved despite a decreased P aO 2 . As this was associated with a reduced response of cerebral blood volume to hypocapnia, adaptation of cerebrovascular reactivity might have occurred.
Type of Medium:
Online Resource
ISSN:
1664-042X
DOI:
10.3389/fphys.2023.1160050
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2023
detail.hit.zdb_id:
2564217-0
