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Analysis of dynamic autoregulation assessed by the cuff deflation method.
Roman Hlatky1, Alex B Valadka, Claudia S Robertson
1Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA. hlatky@uthscsa.edu
Neurocritical Care
|April 22, 2006
Summary
Dynamic testing of cerebral pressure autoregulation using cuff deflation is safe for head-injured patients. Mean arterial pressure (MAP) can substitute for cerebral perfusion pressure (CPP) in autoregulatory index (ARI) calculations.
Area of Science:
- Neuroscience
- Critical Care Medicine
- Physiology
Background:
- Dynamic testing of cerebral pressure autoregulation is practical for critically ill patients.
- Systemic and cerebral effects of cuff deflation in head-injured patients require study.
- Cuff deflation is generally safe in healthy individuals.
Purpose of the Study:
- To examine the physiological effects of cuff deflation in severely head-injured patients.
- To assess the impact of cuff deflation on autoregulatory index (ARI) calculations.
Main Methods:
- Analyzed 388 thigh cuff deflations in 24 severely head-injured patients.
- Recorded physiological parameters before, during, and after transient blood pressure decrease.
- Calculated autoregulation using the autoregulatory index (ARI) from 0 to 9.
Main Results:
- Mean arterial blood pressure (MAP) decreased by 19 mmHg, with nadir at 8 seconds post-deflation.
- Early MAP and cerebral perfusion pressure (CPP) tracings were nearly identical.
- ARI calculations using MAP or CPP showed minimal differences (≤1 in >93% of studies).
Conclusions:
- Dynamic testing of cerebral pressure autoregulation causes minor physiological perturbations.
- Early MAP and CPP changes after cuff deflation are comparable.
- MAP can reliably substitute for CPP in ARI calculations for brain-injured patients.