Differential cerebrovascular CO2 reactivity in anterior and posterior cerebral circulations

Morphometric evaluation of the delayed cerebral arteries response to acetazolamide test in patients with chronic carotid artery stenosis using computed tomography angiography

“…Therefore, our study supports earlier physiological reports suggesting regional differences in CO 2 reactivity [16,17]. Nevertheless, both Sato et al [16] and Skow et al [17] used Doppler ultrasound and measured CBF velocity as a surrogate of CBF in healthy subjects.…”

“…Therefore, our study supports earlier physiological reports suggesting regional differences in CO 2 reactivity [16,17]. Nevertheless, both Sato et al [16] and Skow et al [17] used Doppler ultrasound and measured CBF velocity as a surrogate of CBF in healthy subjects. Doppler ultrasound as a method to estimate CBF is even more questionable in patients with chronic artery stenosis due to turbulent blood flow in the area of stenosis [7,11,14].…”

“…Physiological studies suggest regional differences in CO 2 regulation of blood flow between the internal carotid artery (ICA) and vertebrobasilar circulation. Lower CO 2 reactivity in the vertebrobasilar system may be beneficial for preserving blood flow to the medulla oblongata to maintain vital systemic functions, while higher CO 2 reactivity in the ICA system may imply a larger tolerance for varied blood flow in the cerebral cortex [16,17].…”

Comparing and characterizing transient and steady‐state tests of the peripheral chemoreflex in humans

“…This is expected, as the cerebrovasculature is more reactive to small fluctuations in CO 2 compared with O 2 within the physiological range (Willie et al 2012). Additionally, absolute MCA reactivity was nearly double that of the PCA for both tests, another well-described phenomenon that is consistent with other reports (Willie et al 2012;Skow et al 2013). Despite the statistical significance of these cardiovascular and cerebrovascular changes, they were all very small in magnitude and short in duration, and therefore were unlikely to confound the ventilatory responses to the transient tests.…”

“…Bilateral transcranial Doppler ultrasound was employed using a 2 MHz pulsed Doppler ultrasound system (PMD150B; Spencer Technologies, Redmond, WA, USA) to insonate and measure the cerebral blood velocity of the middle cerebral artery (MCA) and posterior cerebral artery (PCA). To ensure that these vessels were accurately located, previously described verification techniques were used (Willie et al 2011;Skow et al 2013). Mean cerebral blood velocity was calculated as a weighted mean from the envelope of the velocity trace using LabChart.…”