. 2023 Jan 9;324(2):R207–R215. doi: 10.1152/ajpregu.00228.2022

Table 2.

Hemodynamic and gas exchange variables during stepped hypercapnia

	Room Air	2% CO₂	4% CO₂	6% CO₂	ANOVA P Values
	Room Air	2% CO₂	4% CO₂	6% CO₂	Group	Condition	Interaction
ETCO₂, mmHg
Early	44 ± 3	44 ± 3	48 ± 3	51 ± 3	0.82	<0.01	0.62
Late	43 ± 4	44 ± 3	47 ± 3	51 ± 3	0.82	<0.01	0.62
MAP, mmHg
Early	109 ± 14	113 ± 15	116 ± 15	119 ± 18	0.28	<0.01	0.27
Late	105 ± 17	106 ± 16	110 ± 16	112 ± 16	0.28	<0.01	0.27
MCAv, cm/s
Early	62 ± 14	62 ± 15	68 ± 17	77 ± 19	0.47	<0.01	0.23
Late	63 ± 10	65 ± 11	73 ± 12	81 ± 11	0.47	<0.01	0.23
CVCi, cm/s/mmHg
Early	0.58 ± 0.14	0.56 ± 0.15	0.60 ± 0.17	0.66 ± 0.18	0.20	<0.01	0.09
Late	0.61 ± 0.11	0.62 ± 0.11	0.67 ± 0.13	0.73 ± 0.13	0.20	<0.01	0.09
PI, AU
Early	0.80 ± 0.10	0.81 ± 0.11	0.77 ± 0.09	0.73 ± 0.09	0.88	<0.01	0.42
Late	0.80 ± 0.09	0.79 ± 0.11	0.77 ± 0.11	0.74 ± 0.11	0.88	<0.01	0.42

Values are presented as means ± SD. CO₂, carbon dioxide; CVCi, cerebrovascular conductance index; ETCO₂, end-tidal carbon dioxide partial pressure; MAP, mean arterial pressure; MCAv, mean middle cerebral artery blood velocity; PI, pulsatility index. Boldface terms represent significant P values.