Rapid assessment of cerebral autoregulation by near-infrared spectroscopy and a single dose of phenylephrine.
Rapid bedside determination of cerebral blood pressure autoregulation (AR) may improve clinical utility. We tested the hypothesis that cerebral Hb oxygenation (HbDiff) and cerebral Hb volume (HbTotal) measured by near-infrared spectroscopy (NIRS) would correlate with cerebral blood flow (CBF) after single dose phenylephrine (PE). Critically ill patients requiring artificial ventilation and arterial lines were eligible. During rapid blood pressure rise induced by i.v. PE bolus, ΔHbDiff and ΔHbTotal were calculated by subtracting values at baseline (normotension) from values at peak blood pressure elevation (hypertension). With the aid of NIRS and bolus injection of indocyanine green, relative measures of CBF, called blood flow index (BFI), were determined during normotension and during hypertension. BFI during hypertension was expressed as percentage from BFI during normotension (BFI%). Autoregulation indices (ARIs) were calculated by dividing BFI%, ΔHbDiff, and ΔHbTotal by the concomitant change in blood pressure. In 24 patients (11 newborns and 13 children), significant correlations between BFI% and ΔHbDiff (or ΔHbTotal) were found. In addition, the associations between Hb-based ARI and BFI%-based ARI were significant with correlation coefficients of 0.73 (or 0.72). Rapid determination of dynamic AR with the aid of cerebral Hb signals and PE bolus seems to be reliable.
Department of Pediatrics, University of Berne, Inselspital, 3010 Berne, Switzerland. bendicht.wagner@insel.ch
Bendicht P
BP
Wagner
Roland A
RA
Ammann
Denis C G
DC
Bachmann
Susanne
S
Born
Andreas
A
Schibler
D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D004396:Coloring Agents; D005260:Female; D006706:Homeostasis; D006801:Humans; D007208:Indocyanine Green; D007223:Infant; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D015278:Intensive Care Units, Pediatric; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D010108:Oxyhemoglobins / Q000378:metabolism; D010656:Phenylephrine; D019095:Point-of-Care Systems; D012039:Regional Blood Flow / Q000187:drug effects; D019265:Spectroscopy, Near-Infrared; D013557:Switzerland; D013997:Time Factors; D014662:Vasoconstrictor Agents
D015415:Biomarkers; D004396:Coloring Agents; D010108:Oxyhemoglobins; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D007208:Indocyanine Green