No influence of steady-state postural changes on cerebrovascular compliance in humans

• Published in: Applied physiology, nutrition, and metabolism nutrition, and metabolism, 2024-09, Vol.49 (9), p.1210-1216
• Main Authors: Kells, Alicia M, Moir, M Erin, Coombs, Geoff B, D'Souza, Andrew W, Klassen, Stephen A, Al-Khazraji, Baraa K, Shoemaker, J Kevin
• Format: Article
• Language: English
• Subjects: Adult; Arterial Pressure; Blood Flow Velocity - physiology; Blood Pressure - physiology; Brachial Artery - physiology; Cerebrovascular Circulation - physiology; Compliance; Female; Forearm - blood supply; Hemodynamics; Humans; Intracranial pressure; Male; Middle Cerebral Artery - physiology; Posture; Posture - physiology; Sitting Position; Standing Position; Supine Position - physiology; Vascular Resistance - physiology; Young Adult
• ISSN: 1715-5312; 1715-5320; 1715-5320
• DOI: 10.1139/apnm-2023-0447

The aim of this study was to determine the effect of posture changes on vascular compliance in intracranial (brain) versus extracranial vascular beds (forearm). Eighteen young adults (nine females) performed a supine-to-seated-to-standing protocol involving 5 min of rest in each position. Continuous blood pressure, middle cerebral artery (MCA) blood velocity, and brachial artery blood velocity were recorded at each posture. Three to five consecutive steady-state cardiac cycles at each posture were analyzed by a four-element lumped parameter modified Windkessel model to calculate vascular compliance. Mean arterial pressure (MAP) increased from supine to seated (76(9) vs. 81(12) mmHg;  = 0.006) and from supine to standing (76(9) vs. 82(13) mmHg;  = 0.034). Mean blood flow was greater in the MCA relative to the forearm (forearm: 40(5) mL·min , MCA: 224(17) mL·min ; main effect