method for linear quantification of the dynamic pressure-flow relation: The CARNet study

Editor’s comment: This paper is a laudable joint initiative by a group of researchers in the Cerebral Autoregulation Research Network (CARNnet -http://www.car-net.org/) to assess one of the most commonly used techniques for the measurement of autoregulation (Transfer Function Analysis). Different groups internationally use slightly different variants of the methods, and this paper addresses the justified concern that small differences in analysis technique may be a confounding factor in comparing results of different studies. Considerable dispersion was indeed observed in results of analysing identical datasets in different groups (though inferences as to impairment of autoregulation were generally consistent). Of additional concern is the observation that even when all groups were using supposedly identical methods, results differed considerably. This highlights the need for quality control, more training and multidisciplinary collaboration to improve robustness of results and compatibility between studies, a lesson one hopes might be taken up by the wider research community.