Moderate correlation between breath-holding and CO(2) inhalation/hyperventilation methods for transcranial doppler evaluation of cerebral vasoreactivity

J Clin Ultrasound. Nov-Dec 2012;40(9):554-8. doi: 10.1002/jcu.21944. Epub 2012 May 25.


Background: Both CO(2) inhalation followed by hyperventilation and breath-holding have been utilized to measure cerebral vasomotor reactivity (VMR) but their correlation has been poorly studied and understood.

Methods: A retrospective study was conducted in 143 subjects (62.6 ± 15.8 years old, 64% men) with transcranial Doppler ultrasonography measurement of mean flow velocity (MFV) at baseline, after 30 seconds of breath-holding, and after CO(2) inhalation followed by hyperventilation, in the left and right middle cerebral artery. Breath-holding index (BHI) was calculated as the percentage of MFV increase from baseline per second of apnea. CO(2) inhalation/hyperventilation index (CO(2) /HV) was calculated as the percentage of MFV difference between CO(2) inhalation and hyperventilation.

Results: There were 75 carotid arteries with >70% stenosis or occlusion, and 18 middle cerebral arteries with >50% stenosis or occlusion. The mean BHI was 0.93 ± 0.7 and 0.89 ± 0.6, whereas the mean CO(2) /HV was 61 ± 26% and 60 ± 26%, respectively, on the right and left sides. The correlation between BHI and CO(2) /HV was moderate on the right (r = 0.33; p < 0.01) and left sides (r = 0.38; p < 0.01). Multivariate linear regression analysis indicated that age (p = 0.01) and history of stroke (p = 0.007) were associated independently with an impaired VMR on the right as measured by CO(2) /HV. No predictors for impaired VMR by CO(2) /HV on the left and by BHI on either side were found.

Conclusions: CO(2) /HV and BHI are only moderately correlated. Further studies are necessary to determine which method more accurately predicts clinical morbidity. © 2012 Wiley Periodicals, Inc. J Clin Ultrasound 2012; Published online in Wiley Online Library.

MeSH terms

  • Blood Flow Velocity
  • Breath Holding*
  • Carbon Dioxide
  • Cerebrovascular Circulation*
  • Cerebrovascular Disorders / diagnostic imaging*
  • Cerebrovascular Disorders / physiopathology
  • Female
  • Hemodynamics
  • Humans
  • Hyperventilation*
  • Inhalation / physiology*
  • Male
  • Middle Aged
  • Middle Cerebral Artery / diagnostic imaging
  • Retrospective Studies
  • Ultrasonography, Doppler, Transcranial / methods*


  • Carbon Dioxide