Transfer function analysis of dynamic cerebral autoregulation: A white paper from the International Cerebral Autoregulation Research Network

Cerebral autoregulation is the intrinsic ability of the brain to maintain adequate cerebral perfusion in the presence of blood pressure changes. A large number of methods to assess the quality of cerebral autoregulation have been proposed over the last 30 years. However, no single method has been universally accepted as a gold standard. Therefore, the choice of which method to employ to quantify cerebral autoregulation remains a matter of personal choice. Nevertheless, given the concept that cerebral autoregulation represents the dynamic relationship between blood pressure (stimulus or input) and cerebral blood flow (response or output), transfer function analysis became the most popular approach adopted in studies based on spontaneous fluctuations of blood pressure. Despite its sound theoretical background, the literature shows considerable variation in implementation of transfer function analysis in practice, which has limited comparisons between studies and hindered progress towards clinical application. Therefore, the purpose of the present white paper is to improve standardisation of parameters and settings adopted for application of transfer function analysis in studies of dynamic cerebral autoregulation. The development of these recommendations was initiated by (but not confined to) the Cerebral Autoregulation Research Networ

Transfer function analysis of dynamic cerebral autoregulation: a CARNet white paper 2022 update

Cerebral autoregulation (CA) refers to the control of cerebral tissue blood flow (CBF) in response tochanges in perfusion pressure. Due to the challenges of measuring intracranial pressure, CA is oftendescribed as the relationship between mean arterial pressure (MAP) and CBF. Dynamic CA (dCA) canbe assessed using multiple techniques, with transfer function analysis (TFA) being the most common.A 2016 white paper by members of an international Cerebrovascular Research Network (CARNet)that is focused on CA strove to improve TFA standardization by way of introducing data acquisition,analysis, and reporting guidelines. Since then, additional evidence has allowed for the improvementand refinement of the original recommendations, as well as for the inclusion of new guidelines toreflect recent advances in the field. This second edition of the white paper contains more robust,evidence-based   recommendations,   which   have   been   expanded   to   address   current   streams   ofinquiry, including optimizing MAP variability, acquiring CBF estimates from alternative methods,estimating   alternative   dCA   metrics,   and   incorporating   dCA   quantification   into   clinical   trials.Implementation of these new and revised recommendations is important to improve the reliabilityand   reproducibility   of   dCA   studies,   and   to   facilitate   inter-institutional   collaboration   and   thecomparison of results between studies.</p

Transfer function analysis of dynamic cerebral autoregulation: A white paper from the International Cerebral Autoregulation Research Network

Cerebral autoregulation is the intrinsic ability of the brain to maintain adequate cerebral perfusion in the presence of blood pressure changes. A large number of methods to assess the quality of cerebral autoregulation have been proposed over the last 30 years. However, no single method has been universally accepted as a gold standard. Therefore, the choice of which method to employ to quantify cerebral autoregulation remains a matter of personal choice. Nevertheless, given the concept that cerebral autoregulation represents the dynamic relationship between blood pressure (stimulus or input) and cerebral blood flow (response or output), transfer function analysis became the most popular approach adopted in studies based on spontaneous fluctuations of blood pressure. Despite its sound theoretical background, the literature shows considerable variation in implementation of transfer function analysis in practice, which has limited comparisons between studies and hindered progress towards clinical application. Therefore, the purpose of the present white paper is to improve standardisation of parameters and settings adopted for application of transfer function analysis in studies of dynamic cerebral autoregulation. The development of these recommendations was initiated by (but not confined to) the Cerebral Autoregulation Research Network (CARNet - www.car-net.org)