Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Hubei University for Nationalities, Enshi, Hubei, China.
Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States; Jishou University, Jishou, Hunan, China.
Respir Physiol Neurobiol. 2020 Jan;271:103306. doi: 10.1016/j.resp.2019.103306. Epub 2019 Sep 23.
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.
Hypoxia-induced changes in arterial (SaO) and cerebral tissue (ScO) O saturation, middle cerebral arterial flow velocity (V), 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% O.
Although pre-hypoxia SaO did not differ between the groups, ScO 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 (P < 0.05). SaO fell less sharply (P < 0.05) in the elderly subjects during the first and fifth hypoxia exposures. Moreover, the responses of ScO, V, 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.
The elderly adults safely tolerated cyclic, moderate hypoxemia which lowered SaO by 20-25%, despite dampening of cerebrovascular and cardiac responses to hypoxemia.
衰老对分级低氧血症期间脑血管功能和组织氧合的影响尚不完全清楚。本研究比较了周期性低氧-复氧过程中这些变量的年龄效应。
比较了 12 名老年（71±2 岁，7 名女性）和 13 名年轻（24±3 岁，5 名女性）成年人在第一次和第五次暴露于 10%O 时的动脉（SaO）和脑组织（ScO）O 饱和度、大脑中动脉血流速度（V）、估计的脑血管导纳（CVC）、心率（HR）和通气的缺氧诱导变化。
尽管两组预缺氧 SaO 无差异，但老年组（68.4±1.2%）的 ScO 低于年轻组（73.8±0.9%），与静息 V 较低有关（P<0.05）。在第一次和第五次低氧暴露期间，老年组 SaO 下降幅度较小（P<0.05）。此外，老年组 ScO、V、CVC、HR 和呼吸频率对低氧的反应减弱。在年轻和老年受试者中，动脉收缩压和舒张压在低氧期间下降 2-6mmHg。因此，与年轻人相比，在常压低氧期间，老年人的低氧发展得更缓慢，这与老年人代谢需求减少一致。
尽管对低氧的脑血管和心脏反应减弱，但老年成年人安全耐受周期性中度低氧，SaO 降低 20-25%。
