Fig. 2.
Effect of hypercapnia on cerebral autoregulation. Autoregulation curves are in black at normocapnia and red at hypercapnia. Cerebral resistance vessels are illustrated in red/pink. The bold solid blue arrows indicate the dynamic shift of the maximally dilated and constricted cerebral resistance vessels at hypercapnia. The dashed black and blue lines/arrows indicate the lower and upper limits at normocapnia and hypercapnia, respectively. A = the curve below the lower limit; B = the plateau at normocapnia (B0), mild hypercapnia (B1), and severe hypercapnia (B2); C = the curve above the upper limit at normocapnia (C0), mild hypercapnia (C1), and severe hypercapnia (C2); CBF = cerebral blood flow; CPP = cerebral perfusion pressure; LL = the lower limit at normocapnia (LL0), mild hypercapnia (LL1), and severe hypercapnia (LL2); R = calibers of cerebral resistance vessels at normocapnia (R0), mild hypercapnia (R1), and severe hypercapnia (R2); UL = the upper limit at normocapnia (UL0), mild hypercapnia (UL1), and severe hypercapnia (UL2).