Date of this Version
UCARE Poster session, University of Nebraska-Lincoln Research Fair, April 2016, Lincoln, NE.
Cerebrovascular reactivity (CVR) is a key factor in regulating blood flow into the brain, and a marker for vascular disease. If the brain's regulatory system is not working, a patient may be in serious trouble. Testing of CVR is one method of assessing the brain's regulatory capabilities. Transcranial Doppler ultrasound (TCD) is one tool to measure CVR. In this method, carbon dioxide in the blood is transiently increased (such as with the holding of breath), and the resulting blood flow in the brain is measured. In this study, we are going to measure the variability of the breathholding index.
Within the four subjects, the standard deviations of the CVR measurements are 0.27, 0.20, 0.15, and 0.61 respectively, with an overall standard deviation of 0.31 across the population. The standard deviation between the average CVR measurements of each subject is 0.09. The CVR measurement is usually higher after the first breathholding for each subject, with the following two CVR measurements being lower and less variable. There is no significant increase or decrease in the mean arterial blood pressure (MAP) before or after breath-holding. In conclusion, the breath-holding maneuver is a convenient and well-tolerated screening method for CVR. However, this experiment showed a high variability in this measurement. To obtain an accurate result, three breath-holding indices need to be taken and averaged for each subject.