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.