Reduced Cerebrovascular Response to CO2Rebreathing in Spinal Cord Injury

Individuals with spinal cord injury (SCI) are at increased risk for an array of health problems during the chronic stages of injury. Among these is a greater risk of stroke. One potential culprit is impairment in cerebrovascular responses to changes in arterial blood gases. In able-bodied individuals, the cerebral vasculature dilates in response to elevated arterial carbon dioxide (i.e. cerebrovascular reactivity), and impairment in cerebrovascular reactivity has been linked to increased risk of stroke. Therefore we examined the cerebral blood flow response to progressive increases in arterial CO2 via rebreathing in individuals with SCI (n = 7, from C5 to T8) and able-bodied individuals (n = 6). We measured end-tidal CO2, cerebral blood flow velocity (Doppler ultrasound), arterial pressure (photoplethysmography) and derived cerebrovascular reactivity as the slope between end-tidal CO2 and cerebrovascular conductance. We found a significantly reduced cerebrovascular reactivity in subjects with SCI (0.0791±...