Rebecca H Clough, Ronney B Panerai, Kannaphob Ladthavorlaphatt, Thompson G Robinson, Jatinder S Minhas
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引用次数: 0
Abstract
Arterial carbon dioxide (PaCO2) and posture influence the middle (MCAv) and posterior (PCAv) cerebral artery blood velocitiesbut there is paucity of data about their interaction and need for an integrated model of their effects, including dynamic cerebral autoregulation (dCA). In 22 participants (11 male, age 30.2 ± 14.3 years), blood pressure (BP, Finometer), dominant MCAv and non-dominant PCAv (transcranial Doppler ultrasound), end-tidal CO2 (EtCO2, capnography) and heart rate (HR, ECG) were recorded continuously. Two recordings (R) were taken when the participant was supine (R1, R2), two taken when the participant was sitting (R3, R4), and two taken when the participant was standing (R5, R6). R1, R3 and R5 consisted of 3 minutes of 5% CO2 through a mask and R2, R4 and R6 consisted of 3 minutes of paced hyperventilation. The effects of PaCO2 were expressed with a logistic curve model (LCM) for each parameter. dCA was expressed by the autoregulation index (ARI), dervived by transfer function analysis. Standing shifted LCM to the left for MCAv (p<0.001), PCAv (p<0.001), BP (p=0.03) and ARI (p=0.001); downwards for MCAv and PCAv (both p<0.001), and upwards for HR (p<0.001). For BP, LCM was shifted downwards by sitting and standing (p=0.024). For ARI, the hypercapnic range of LCM was shifted upwards during standing (p<0.001). A more complete mapping of the combined effects of posture and arterial CO2 on the cerebral circulation and peripheral variables can be obtained with the LCM over a broad physiological range of EtCO2 values.
期刊介绍:
The Journal of Applied Physiology publishes the highest quality original research and reviews that examine novel adaptive and integrative physiological mechanisms in humans and animals that advance the field. The journal encourages the submission of manuscripts that examine the acute and adaptive responses of various organs, tissues, cells and/or molecular pathways to environmental, physiological and/or pathophysiological stressors. As an applied physiology journal, topics of interest are not limited to a particular organ system. The journal, therefore, considers a wide array of integrative and translational research topics examining the mechanisms involved in disease processes and mitigation strategies, as well as the promotion of health and well-being throughout the lifespan. Priority is given to manuscripts that provide mechanistic insight deemed to exert an impact on the field.