Is dynamic cerebral autoregulation measurement using transcranial Doppler ultrasound reproducible in the presence of high concentration oxygen and carbon dioxide?
Reliability of cerebral blood flow velocity (CBFV) and dynamic cerebral autoregulation estimates (expressed as autoregulation index: ARI) using spontaneous fluctuations in blood pressure (BP) has been demonstrated. However, reliability during co-administration of O2 and CO2 is unknown. Bilateral CBFV (using transcranial Doppler), BP and RR interval recordings were performed in healthy volunteers (seven males, four females, age: 54  ±  10 years) on two occasions over 9  ±  4 d. Four 5 min recordings were made whilst breathing air (A), then 5%CO2 (C), 80%O2 (O) and mixed O2  +  CO2 (M), in random order. CBFV was recorded; ARI was calculated using transfer function analysis. Precision was quantified as within-visit standard error of measurement (SEM) and the coefficient of variation (CV). CBFV and ARI estimates with A (SEM: 3.85 & 0.87; CV: 7.5% & 17.8%, respectively) were comparable to a previous reproducibility study. The SEM and CV with C and O were similar, though higher values were noted with M; Bland-Altman plots indicated no significant bias across all gases for CBFV and ARI (bias  <0.06 cm s(-1) and  <0.05, respectively). Thus, transcranial-Doppler-ultrasound-estimated CBFV and ARI during inhalation of O2 and CO2 have acceptable levels of reproducibility and can be used to study the effect of these gases on cerebral haemodynamics.
Ageing and Stroke Medicine, Department of Cardiovascular Sciences, University of Leicester, Stroke Research Office, Victoria Building, Leicester Royal Infirmary, Leicester LE1 5WW, UK. NIHR Leicester Cardiovascular Biomedical Research Unit, University of Leicester, Leicester, UK. Department of Stroke Medicine, University Hospitals of Leicester NHS Trust, Leicester, UK.
Jatinder S
JS
Minhas
Nazia F
NF
Syed
Victoria J
VJ
Haunton
Ronney B
RB
Panerai
Thompson G
TG
Robinson
Amit K
AK
Mistri
D000328:Adult; D000368:Aged; D000388:Air; D002245:Carbon Dioxide / Q000008:administration & dosage*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003935:Diagnostic Techniques, Cardiovascular; D005260:Female; D005385:Fingers; D006339:Heart Rate / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D064926:Neurophysiological Monitoring / Q000379:methods; D010100:Oxygen / Q000008:administration & dosage*; D015203:Reproducibility of Results; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
D002245:Carbon Dioxide; D010100:Oxygen