Fluctuations in Cerebral Hemodynamics [report]

Miroslaw Latka, Dariusz Latka
2003 unpublished
Introduction The statistical properties of physiological fluctuations, such as found in the time series for heartbeat dynamics (1), respiration (2) , human locomotion (3; 4) and posture control (5), have been the focus of interdisciplinary research for more than two decades (6) . The rationale for this persistent interest has been twofold: to better understand complex self-regulatory control systems that produce such fluctuations (7) and to describe their dynamics with tools capable of
more » ... their nonlinear and/or non-stationary character (7). One outcome of this research has been a profound change in our understanding of the significance of homeostasis. Homeostasis -an organism's tendency to maintain approximately constant values of vital biological parameters, such as heart rate or blood pressure, has been the cornerstone of modern physiology since the turn of the twentieth century. However, the discovery of fractal and multifractal properties in physiological time series has lead to the conclusion that the intrinsic variability of many physiological phenomena reflects the adaptability of the underlying motorcontrol systems (8; 9). This change of paradigm, associated with how we view the dynamics of physiologic phenomena, has not, to date, significantly influenced the studies of fluctuations in cerebral hemodynamics. In particular, the interpretation of the fluctuations in either intracranial pressure (ICP) or blood flow velocity in major arteries, remains unaltered. The slow adoption of ideas implemented earlier, for example, in cardiac dynamics, is to some extent surprising, taking into account that ICP monitoring has long been the fundamental component of critical care management of patients with severe brain injury. Moreover, transcranial Doppler ultrasonography (TCD), which allows physicians to noninvasively study cerebral blood flow velocities, is by now routinely employed in clinical practice.
doi:10.21236/ada425143 fatcat:j4royupdkfgfvc5eym2lsry4xu