Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America.
Department of Physical Medicine and Rehabilitation, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America.
PLoS One. 2020 Mar 2;15(3):e0229049. doi: 10.1371/journal.pone.0229049. eCollection 2020.
Cerebrovascular reactivity and cerebral autoregulation are two major mechanisms that regulate cerebral blood flow. Both mechanisms are typically assessed in either supine or seated postures, but the effects of body position and sex differences remain unclear. This study examined the effects of body posture (supine vs. seated vs. standing) on cerebrovascular reactivity during hyper and hypocapnia and on cerebral autoregulation during spontaneous and slow-paced breathing in healthy men and women using transcranial Doppler ultrasonography of the middle cerebral artery. Results indicated significantly improved cerebrovascular reactivity in the supine compared with seated and standing postures (supine = 3.45±0.67, seated = 2.72±0.53, standing = 2.91±0.62%/mmHg, P<0.0167). Similarly, cerebral autoregulatory measures showed significant improvement in the supine posture during slow-paced breathing. Transfer function measures of gain significantly decreased and phase significantly increased in the supine posture compared with seated and standing postures (gain: supine = 1.98±0.56, seated = 2.37±0.53, standing = 2.36±0.71%/mmHg; phase: supine = 59.3±21.7, seated = 39.8±12.5, standing = 36.5±9.7°; all P<0.0167). In contrast, body posture had no effect on cerebral autoregulatory measures during spontaneous breathing. Men and women had similar cerebrovascular reactivity and similar cerebral autoregulation during both spontaneous and slow-paced breathing. These data highlight the importance of making comparisons within the same body position to ensure there is not a confounding effect of posture.
脑血管反应性和脑自动调节是调节脑血流的两个主要机制。这两种机制通常在仰卧或坐姿下进行评估，但体位和性别差异的影响仍不清楚。本研究使用经颅多普勒超声检查大脑中动脉，在健康男性和女性中，研究了体位（仰卧、坐姿和站立）对高碳酸血症和低碳酸血症期间脑血管反应性以及自主呼吸和慢呼吸期间脑自动调节的影响。结果表明，与坐姿和站立相比，仰卧位时脑血管反应性显著改善（仰卧位=3.45±0.67，坐姿=2.72±0.53，站立位=2.91±0.62%/mmHg，P<0.0167）。同样，在慢呼吸期间，仰卧位时脑自动调节措施也有显著改善。与坐姿和站立相比，仰卧位时传递函数的增益显著降低，相位显著增加（增益：仰卧位=1.98±0.56，坐姿=2.37±0.53，站立位=2.36±0.71%/mmHg；相位：仰卧位=59.3±21.7，坐姿=39.8±12.5，站立位=36.5±9.7°；所有 P<0.0167）。相比之下，体位对自主呼吸期间的脑自动调节措施没有影响。男性和女性在自主呼吸和慢呼吸期间均具有相似的脑血管反应性和脑自动调节。这些数据强调了在同一体位内进行比较的重要性，以确保没有体位的混杂影响。
