Reduced cerebrovascular and cardioventilatory responses to intermittent hypoxia in elderly

Xiaoli Liu; Xiaoan Chen; Geoffrey Kline; Sarah E Ross; James R Hall; Yanfeng Ding; Robert T Mallet; Xiangrong Shi

doi:10.1016/j.resp.2019.103306

Reduced cerebrovascular and cardioventilatory responses to intermittent hypoxia in elderly

Respir Physiol Neurobiol. 2020 Jan:271:103306. doi: 10.1016/j.resp.2019.103306. Epub 2019 Sep 23.

Authors

Xiaoli Liu¹, Xiaoan Chen², Geoffrey Kline³, Sarah E Ross⁴, James R Hall⁵, Yanfeng Ding³, Robert T Mallet⁶, Xiangrong Shi⁷

Affiliations

¹ Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Hubei University for Nationalities, Enshi, Hubei, China.
² Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Jishou University, Jishou, Hunan, China.
³ Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, Texas, United States.
⁴ Department of Internal Medicine, University of North Texas Health Science Center, Fort Worth, Texas, United States; Institutes for Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas, United States.
⁵ Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Institutes for Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas, United States.
⁶ Department of Physiology & Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, United States.
⁷ Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Institutes for Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas, United States. Electronic address: Xiangrong.shi@unthsc.edu.

PMID: 31557538
DOI: 10.1016/j.resp.2019.103306

Abstract

Background: The impact of aging on cerebrovascular function and tissue oxygenation during graded hypoxemia is incompletely known. This study compared the age effect on these variables during cyclic hypoxemia-reoxygenation.

Methods: Hypoxia-induced changes in arterial (SaO₂) and cerebral tissue (ScO₂) O₂ saturation, middle cerebral arterial flow velocity (V_MCA), estimated cerebral vascular conductance (CVC), heart rate (HR) and ventilation were compared between 12 elderly (71 ± 2 yr, 7 women) and 13 young (24 ± 3 yr, 5 women) adults during the first and fifth 5-min exposures to 10% O₂.

Results: Although pre-hypoxia SaO₂ did not differ between the groups, ScO₂ was lower (P < 0.05) in the elderly (68.4 ± 1.2%) than young (73.8 ± 0.9%) adults, commensurate with a lower resting V_MCA (P < 0.05). SaO₂ fell less sharply (P < 0.05) in the elderly subjects during the first and fifth hypoxia exposures. Moreover, the responses of ScO₂, V_MCA, CVC, HR and breathing frequency to hypoxia were attenuated in the elderly subjects. Systolic and diastolic arterial pressures fell by 2-6 mmHg during hypoxia in both young and elderly. Thus, hypoxemia developed more gradually in elderly than young adults during normobaric hypoxia, concordant with a reduced metabolic demand in the elderly.

Conclusions: The elderly adults safely tolerated cyclic, moderate hypoxemia which lowered SaO₂ by 20-25%, despite dampening of cerebrovascular and cardiac responses to hypoxemia.

Keywords: Aging; Arterial oxygen saturation; Cerebral blood flow; Cerebral tissue oxygenation; Heart rate; Hypoxemia; Ventilation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Aged
Aging / physiology*
Blood Pressure / physiology*
Brain / blood supply
Brain / diagnostic imaging
Brain / physiology*
Cerebrovascular Circulation / physiology*
Female
Heart Rate / physiology*
Humans
Hypoxia / diagnostic imaging
Hypoxia / physiopathology*
Male
Pulmonary Ventilation / physiology*
Ultrasonography, Doppler, Transcranial / methods
Young Adult