The influence of age and sex on cerebrovascular reactivity and ventilatory response to hypercapnia in children and adults.

NEW FINDINGS: What is the central question of this study? This study investigated intracranial cerebrovascular and ventilatory reactivity to 6% CO2 in children and adults and explored dynamic ventilatory and cerebrovascular onset responses. What is the main finding and its importance? We show cerebrovascular reactivity is similar in children and adults, but the intracranial blood velocity onset response was markedly attenuated in children. Sex differences were apparent, with greater increases in intracranial blood velocity in females, and lower ventilatory reactivity in adult females. Our study confirms the importance of investigating dynamic onset responses when assessing the influence of development on cerebrovascular regulation. ABSTRACT: The purpose of this study was to compare the integrated intracranial cerebrovascular reactivity (CVR) and hypercapnic ventilatory response (HCVR) between children and adults, as well as explore the dynamic response of the middle cerebral artery mean velocity (MCAV ). Children (n = 20; 9.9 +/- 0.7 years) and adults (n = 21; 24.4 +/- 2.0 years) completed assessment of CVR over 240s using a fixed concentration of inspired CO2 (FI CO2 , 0.06). Baseline MCAV was higher in the adult females compared to the males (p