Format

Send to

Choose Destination
J Neurotrauma. 2018 Dec 1;35(23):2803-2811. doi: 10.1089/neu.2017.5603. Epub 2018 Oct 4.

Validation of Pressure Reactivity and Pulse Amplitude Indices against the Lower Limit of Autoregulation, Part I: Experimental Intracranial Hypertension.

Author information

1
1 Division of Anaesthesia, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom .
2
2 Section of Surgery, Rady Faculty of Health Sciences, University of Manitoba , Winnipeg, Canada .
3
3 Clinician Investigator Program, Rady Faculty of Health Sciences, University of Manitoba , Winnipeg, Canada .
4
4 Section of Brain Physics, Division of Neurosurgery, Addenbrooke's Hospital, University of Cambridge , Cambridge, United Kingdom .
5
5 Department of Anesthesiology and Critical Care Medicine, Johns Hopkins , Baltimore, Maryland.
6
6 Pediatric Cardiology, Texas Children's Hospital , Baylor College of Medicine, Houston, Texas.
7
7 Department of Brain and Cognitive Engineering, Korea University , Seoul, South Korea .
8
8 Institute of Electronic Systems, Warsaw University of Technology , Warsaw, Poland .

Abstract

The purpose of this study was to provide validation of intracranial pressure (ICP) derived continuous indices of cerebrovascular reactivity against the lower limit of autoregulation (LLA). Utilizing an intracranial hypertension model within white New Zealand rabbits, ICP, transcranial Doppler (TCD), laser Doppler flowmetry (LDF), and arterial blood pressure were recorded. Data were retrospectively analyzed in a cohort of 12 rabbits with adequate signals for interrogating the LLA. We derived continuous indices of cerebrovascular reactivity: PRx (correlation between ICP and mean arterial pressure [MAP]), PAx (correlation between pulse amplitude of ICP [AMP] and MAP), and Lx (correlation between LDF-based cerebral blood flow [CBF] and cerebral perfusion pressure [CPP]). LLA was derived via piecewise linear regression of CPP versus LDF or CPP versus systolic flow velocity (FVs) plots. We then produced error bar plots for PRx, PAx, and Lx against 2.5 mm Hg bins of CPP, to display the relationship between these indices and the LLA. We compared the CPP values at clinically relevant thresholds of PRx and PAx, to the CPP defined at the LLA. Receiver operating curve (ROC) analysis was performed for each index across the LLA using 2.5 mm Hg bins for CPP. The mean LLA was 51.5 ± 8.2 mm Hg. PRx and PAx error bar plots demonstrate that each index correlates with the LLA, becoming progressively more positive below the LLA. Similarly, CPP values at clinically relevant thresholds of PRx and PAx were not statistically different from the CPP derived at the LLA. Finally, ROC analysis indicated that PRx and PAx predicted the LAA, with areas under the curve (AUCs) of 0.795 (95% confidence interval [CI]: 0.731-0.857, p < 0.0001) and 0.703 (95% CI: 0.631-0.775, p < 0.0001), respectively. Both PRx and PAx generally agree with LLA within this experimental model of intracranial hypertension. Further analysis of clinically used indices of autoregulation across the LLA within pure arterial hypotension models is required.

KEYWORDS:

LLA; autoregulation; continuous indices; experimental; validation

PMID:
29978744
DOI:
10.1089/neu.2017.5603

Supplemental Content

Full text links

Icon for Atypon
Loading ...
Support Center