Arterial pressure and cerebral blood flow variability: friend or foe? A review.
Variability in arterial pressure and cerebral blood flow has traditionally been interpreted as a marker of cardiovascular decompensation, and has been associated with negative clinical outcomes across varying time scales, from impending orthostatic syncope to an increased risk of stroke. Emerging evidence, however, suggests that increased hemodynamic variability may, in fact, be protective in the face of acute challenges to perfusion, including significant central hypovolemia and hypotension (including hemorrhage), and during cardiac bypass surgery. This review presents the dichotomous views on the role of hemodynamic variability on clinical outcome, including the physiological mechanisms underlying these patterns, and the potential impact of increased and decreased variability on cerebral perfusion and oxygenation. We suggest that reconciliation of these two apparently discrepant views may lie in the time scale of hemodynamic variability; short time scale variability appears to be cerebroprotective, while mid to longer term fluctuations are associated with primary and secondary end-organ dysfunction.
Department of Integrative Physiology, Cardiovascular Research Institute, University of North Texas Health Science Center Fort Worth, TX, USA.
Caroline A
CA
Rickards
Cardiovascular Systems Laboratory, Centre for Translational Physiology, University of Otago Wellington, New Zealand.
Yu-Chieh
YC
Tzeng
blood pressure variability; cerebral blood flow (CBF); cerebral blood flow variability; end organ damage; hemodynamic oscillations