Noninvasive Monitoring of Dynamic Cerebrovascular Autoregulation and ‘Optimal Blood Pressure’ in Normal Adult Subjects
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Cerebrovascular autoregulation can be continuously monitored from slow fluctuations of arterial blood pressure (ABP) and regional cerebral oxygen saturation (rSO2). The purpose of this study was to evaluate the index of dynamic cerebrovascular autoregulation (TOx) and the associated ‘optimal’ ABP in normal adult healthy subjects.
Twenty-eight healthy volunteers were studied. TOx was calculated as the moving correlation coefficient between spontaneous fluctuations of ABP and rSO2. ABP was measured with the Finometer photoplethysmograph. The ABP with optimal autoregulation (ABPOPT) was also determined as the ABP level with the lowest associated TOx (opt-TOx).
Average rSO2 and TOx was 72.3 ± 2.9% and 0.05 ± 0.18, respectively. Two subjects had impaired autoregulation with a TOx > 0.3. The opt-TOx was − 0.1 ± 0.26. ABPOPT was 87.0 ± 16.7 mmHg. The difference between ABP and ABPOPT was − 0.3 ± 7.5 mmHg. In total, 44% of subjects had a deviation of ABP from ABPOPT exceeding 5 mmHg. ABPOPT ranged from 57 to 117 mmHg.
TOx in healthy volunteers on average displays intact autoregulation and ABP close to ABPOPT. However, some subjects have possible autoregulatory dysfunction or a significant deviation of ABP from ABPOPT, which may confer a susceptibility to neurological injury.
KeywordsCerebral autoregulation Optimal cerebral perfusion pressure Near-infrared spectroscopy Neuromonitoring
PP, JB, and AA performed the experiments and data collection. AA, AC, JMW, and MJ planned and designed the study and obtained funding. PP, JB, AA, and MJ analysed the data. PP, JB, AA, AC, JMW, and MJ interpreted the results, drafted and finalized the manuscript.
Source of support
This study was supported by an infrastructure grant from the University of New South Wales.
Compliance with Ethical Standards
Conflict of interest
The authors declare they have no conflict of interest.
The Human Research Ethics Committee of South Western Sydney Local Health District approved this study (HREC/14/LPOOL/135). Written informed consent was obtained from each participating subject.
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