. 2022 Sep 2;323(4):H782–H796. doi: 10.1152/ajpheart.00300.2022

Table 3.

Peak cardiovascular and cerebrovascular responses to hypercapnia

	Model 1: Age			Model 2: Age and Sex					Model 3: Interaction (Age × Sex)
	Model 1: Age			Age		Sex			Model 3: Interaction (Age × Sex)
	P value	R ²	β	P value	β	P value	β	Combined R²	P value	R ²	β Males	β Females
Intracranial cerebrovascular parameters
MCAv, cm/s	0.03	0.07	−0.30 ± 0.13	0.007	−0.35 ± 0.13	0.002	14.0 ± 4.4	0.18	0.28	0.20	−0.49 ± 0.18	−0.21 ± 0.18
CVR, cm⁻¹/mmHg	0.59	0.004	−0.003 ± 0.006	0.45	−0.004 ± 0.006	0.09	0.34 ± 0.20	0.05	0.90	0.05	−0.005 ± 0.008	−0.004 ± 0.008
PI, AU	0.45	0.008	0.003 ± 0.004	0.47	0.003 ± 0.004	0.74	0.046 ± 0.14	0.01	0.72	0.01	0.001 ± 0.005	0.004 ± 0.006
CVCi, cm/s/mmHg	<0.001	0.26	−0.007 ± 0.001	<0.001	−0.007 ± 0.001	0.01	0.11 ± 0.05	0.32	0.83	0.32	−0.007 ± 0.002	−0.007 ± 0.002
CVRi, mmHg/cm/s	<0.001	0.24	0.012 ± 0.003	<0.001	0.013 ± 0.003	0.07	0.16 ± 0.09	0.27	0.43	0.28	0.015 ± 0.004	0.011 ± 0.004
Cardiovascular parameters
MAP, mmHg	<0.001	0.31	0.48 ± 0.10	<0.001	0.47 ± 0.12	0.34	3.24 ± 3.32	0.32	0.30	0.33	0.36 ± 0.14	0.57 ± 0.13
$P {ET}_{C O_{2}}$ , mmHg	0.32	0.01	−0.14 ± 0.13	0.28	−0.15 ± 0.14	0.43	−3.9 ± 4.8	0.02	0.77	0.02	−0.12 ± 0.20	−0.19 ± 0.19
V̇e, L/min	0.74	0.002	−0.017 ± 0.05	0.93	−0.005 ± 0.05	0.04	−3.8 ± 1.8	0.06	0.99	0.06	−0.005 ± 0.05	−0.004 ± 0.08
Extracranial internal carotid artery parameters
ICA diameter dilation, %	0.07	0.06	0.043 ± 0.02	0.06	0.044 ± 0.02	0.56	−0.47 ± 0.79	0.07	0.24	0.09	0.018 ± 0.032	0.072 ± 0.033
Peak velocity, cm/s	0.09	0.05	0.21 ± 0.12	0.13	0.19 ± 0.12	0.14	6.43 ± 4.29	0.09	0.41	0.10	0.29 ± 0.17	0.09 ± 0.17
Peak velocity, Δ%	0.21	0.03	0.27 ± 0.21	0.18	0.27 ± 0.21	0.43	−6.0 ± 7.5	0.04	0.02	0.13	0.78 ± 0.29	−0.20 ± 0.29
Mean blood flow, mL/min	0.02	0.11	7.1 ± 2.8	0.01	7.4 ± 2.8	0.20	−128.7 ± 98.0	0.13	0.86	0.13	6.9 ± 3.9	8.0 ± 4.1
Mean blood flow, Δ%	0.03	0.08	0.50 ± 0.23	0.03	0.51 ± 0.23	0.56	−4.8 ± 8.2	0.09	0.10	0.13	0.87 ± 0.32	0.11 ± 0.34
Shear rate, s⁻¹	0.97	0.00	−0.036 ± 1.02	0.80	−0.24 ± 0.96	0.008	91.82 ± 33.17	0.13	0.11	0.17	1.30 ± 1.33	−1.82 ± 1.35
Shear rate, Δ%	0.10	0.05	0.38 ± 0.23	0.10	0.39 ± 0.23	0.57	−4.5 ± 7.9	0.05	0.01	0.17	0.96 ± 0.31	−1.91 ± 0.31
SR_AUC, s⁻¹	0.17	0.03	−140.7 ± 101.5	0.14	−152.5 ± 101.7	0.25	4136.7 ± 3563.9	0.06	0.53	0.07	−90.37 ± 141.33	−220.80 ± 148.18
SR_{AUC initial}, s⁻¹	0.83	0.001	−2.74 ± 12.93	0.68	−5.29 ± 12.63	0.05	894.89 ± 442.92	0.07	0.07	0.13	16.34 ± 17.09	−29.07 ± 17.92

Values are means ± SD. Boldface indicates significant relationship (P < 0.05). Model 1 presents the relationship between age and the indicated variable. Model 2 presents the addition of sex to the model and the relationship between age and sex with the indicated variable. Model 3 indicates if sex moderates the relationship between age and the indicated variable, with individual β coefficients shown for males and females. In models 1–3, R² value reflects the full model. In models 1 and 3, β represents the unstandardized β coefficient representing the change in variable units for every year increase in age. In model 2, the Δ β coefficient provides the difference in females vs. males in the variable units. CVCi, cerebrovascular conductance index; CVR, cerebrovascular reactivity; CVRi; cerebrovascular resistance index; ICA, internal carotid artery; MAP, mean arterial pressure; MCAv, middle cerebral artery velocity; $P {ET}_{C O_{2}}$ , end-tidal carbon dioxide; PI, pulsatility index; SR_AUC, shear rate area under the curve; V̇e, minute ventilation.