Assessment of dynamic cerebral autoregulation in humans: Is reproducibility dependent on blood pressure variability?

Jan Willem J Elting ,Martin Müller,Marcel Aries,David M Simpson,Bernardo Yelicich,Corina Puppo,Erik D Gommer,Takashi Tarumi,Alexander Caicedo,Stephen J Payne,Sabine Van Huffel,Adam Mahdi,Ricardo C Nogueira,Rong Zhang,Georgios D Mitsis,Kyriaki Kostoglou,Vasilis Z Marmarelis,Ronney B Panerai,José Luis Jara ,Dong-Joon Shin ,Máx Chacón ,Mark Sanders ,Dragana Nikolić ,Edson Bor‐Seng‐Shu ,Jurgen A.h.r Claassen

doi:10.1371/journal.pone.0227651

Abstract

We tested the influence of blood pressure variability on the reproducibility of dynamic cerebral autoregulation (DCA) estimates. Data were analyzed from the 2nd CARNet bootstrap initiative, where mean arterial blood pressure (MABP), cerebral blood flow velocity (CBFV) and end tidal CO2 were measured twice in 75 healthy subjects. DCA was analyzed by 14 different centers with a variety of different analysis methods. Intraclass Correlation (ICC) values increased significantly when subjects with low power spectral density MABP (PSD-MABP) values were removed from the analysis for all gain, phase and autoregulation index (ARI) parameters. Gain in the low frequency band (LF) had the highest ICC, followed by phase LF and gain in the very low frequency band. No significant differences were found between analysis methods for gain parameters, but for phase and ARI parameters, significant differences between the analysis methods were found. Alternatively, the Spearman-Brown prediction formula indicated that prolongation of the measurement duration up to 35 minutes may be needed to achieve good reproducibility for some DCA parameters. We conclude that poor DCA reproducibility (ICC<0.4) can improve to good (ICC > 0.6) values when cases with low PSD-MABP are removed, and probably also when measurement duration is increased.

Highlights

Dynamic cerebral autoregulation (DCA) is a key mechanism in cerebral homeostasis and protects the brain from alterations in blood pressure by arteriolar vasodilatation or constriction [1],[2]
For autoregulation index (ARI) and correlation like methods, no significant correlations were found. This means that the effect of any case removal based on power spectral density (PSD)-mean arterial blood pressure (MABP) levels on reproducibility can be expected to be higher in Transfer Function Analysis (TFA) like methods
Absence of significant correlations does not mean that there can be no benefit in reproducibility following case removals: if only a few outliers exist at low PSD-MABP power, there may not be a significant correlation, but reproducibility statistics such as Intraclass Correlation (ICC) values can still be significantly affected, as they are quite sensitive to even a few outliers

Summary

Introduction

Dynamic cerebral autoregulation (DCA) is a key mechanism in cerebral homeostasis and protects the brain from alterations in blood pressure by arteriolar vasodilatation or constriction [1],[2]. Through this process, cerebral blood flow is preserved at a relatively constant level. Distributions of patient and healthy subject groups overlap considerably which results in poor diagnostic properties. This hampers implementation of DCA measurements as a diagnostic or monitoring tool in clinical practice

Methods

Results

Conclusion