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

Table 4.

Intracranial responses to hypercapnia

Model 1: Age
 Model 2: Age and Sex
 Model 3: Interaction (Age × Sex)
Age
 Sex
P value R 2 β P value β P value β Combined R2 P value R 2 β Males β Females
Kinetic parameters (n = 71, females = 38)
MCAv τ, s 0.013 0.09 0.28 ± 0.11 0.023 0.25 ± 0.11 0.13 5.79 ± 3.77 0.12 0.77 0.12 0.28 ± 0.15 0.22 ± 0.15
MCAv ΔAmp, cm/s 0.49 0.007 0.035 ± 0.05 0.72 0.018 ± 0.05 0.03 3.87 ± 1.74 0.08 0.31 0.09 −0.033 ± 0.071 0.07 ± 0.07
MCAv TD, s 0.05 0.05 0.095 ± 0.048 0.05 0.10 ± 0.049 0.52 −1.12 ± 1.71 0.06 0.13 0.09 0.18 ± 0.07 0.026 ± 0.07
MCAv MRT, s 0.002 0.13 0.37 ± 0.12 0.004 0.35 ± 0.12 0.26 4.67 ± 4.10 0.15 0.37 0.16 0.46 ± 0.17 0.25 ± 0.17
PETCO2 τ, s 0.81 0.001 0.018 ± 0.08 0.79 0.021 ± 0.08 0.84 −0.54 ± 2.63 0.001 0.52 0.008 −0.03 ± 0.11 0.07 ± 0.11
PETCO2 ΔAmp, mmHg 0.004 0.11 0.042 ± 0.01 0.003 0.044 ± 0.01 0.41 −0.42 ± 0.50 0.12 0.64 0.12 0.05 ± 0.02 0.04 ± 0.02
PETCO2 TD, s 0.77 0.001 0.014 ± 0.05 0.81 0.012 ± 0.05 0.71 0.63 ± 1.69 0.003 0.13 0.04 0.086 ± 0.07 −0.062 ± 0.07
PETCO2 MRT, s 0.69 0.002 0.033 ± 0.08 0.70 0.032 ± 0.05 0.97 −0.09 ± 2.80 0.002 0.76 0.004 0.06 ± 0.12 0.007 ± 0.12

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, the R2 value reflects the full model. In model 2, the β coefficient provides the difference in females vs. males in the variable units. Amp, amplitude; MCAv, middle cerebral artery velocity; MRT, mean response time; PETCO2, end-tidal carbon dioxide; τ, time constant; TD, time delay.