Cerebrovascular response to valsalva maneuver: methodology, normal values, and retest reliability

To provide reference values of cerebrovascular reactivity measured with transcranial Doppler ultrasonography in response to rapid changes in blood pressure during the late straining phase (IIb) of a Valsalva maneuver (VM).

Middle cerebral artery blood flow velocity, arterial blood pressure changes, and end-tidal partial carbon dioxide pressure (pCO(2) ) concentrations were simultaneously and noninvasively measured in 60 healthy subjects. Centro-peripheral Valsalva ratio was calculated by the quotient of cerebrovascular reactivity and peripheral arterial blood pressure response to VM during phase IIb. Age dependency and short- and long-term reliability of indices were evaluated. Correlation between the autonomic response and changes of pCO(2) was calculated.

Centro-peripheral Valsalva ratio was higher in younger healthy subjects, whereas peripheral autonomic reactivity appeared age-independent. There was no correlation between dynamic autoregulatory response and pCO(2) . Short- and long-term measurements of autoregulatory indices showed excellent reliability.

VM is a suitable maneuver to evaluate dynamic autonomic response using transcranial Doppler ultrasonography and noninvasive arterial blood pressure monitoring. Autonomic response during VM does not depend on pCO(2) . Normal human subjects show age-dependent centro-peripheral autoregulatory response.