Table 2.

Multiple linear regression analysis of cerebral hemodynamics

		Overall Model	Model Improvement		95% CI
Model	Variable	R2 (P Value)	ΔR2 (P Value)	β	Lower	Upper
Dependent variable: Mean cerebral blood flow velocity (cm/s)
1	Age	0.337 (<0.001)	0.337 (<0.001)	–0.450*	–0.46	–0.24
	Sex			–0.305*	–11.57	–4.37
	BMI			–0.108	–0.79	0.11
2	Z1	0.513 (<0.001)	0.176 (<0.001)	–0.469*	–27.94	–15.89
3	MAP	0.553 (<0.001)	0.041 (<0.001)	0.233*	0.15	0.51
Dependent variable: Systolic cerebral blood flow velocity (cm/sec)
1	Age	0.266 (<0.001)	0.266 (<0.001)	–0.353*	–0.54	–0.22
	Sex			–0.300*	–16.09	–5.60
	BMI			–0.132	–1.23	0.08
2	Z1	0.436 (<0.001)	0.171 (<0.001)	–0.462*	–38.82	–20.89
Dependent variable: Diastolic cerebral blood flow velocity (cm/sec)
1	Age	0.385 (<0.001)	0.385 (<0.001)	–0.556*	–0.41	–0.25
	Sex			–0.222*	–3.96	–1.78
	BMI			–0.076	–0.51	–0.15
2	Z1	0.524 (<0.001)	0.139 (<0.001)	–0.417*	–19.16	–10.18
3	Carotid PP	0.565 (<0.001)	0.056 (<0.001)	0.311*	0.14	0.38
Dependent variable: Pulsatile cerebral blood flow velocity (cm/sec)
1	Age	0.122 (<0.001)	0.122 (<0.001)	–0.078	–0.17	0.06
	Sex			–0.276*	–10.18	–2.75
	BMI			–0.139	–0.86	0.07
2	Z1	0.227 (<0.001)	0.105 (<0.001)	–0.363*	–21.98	–8.34
3	Brachial DBP	0.314 (<0.001)	0.087 (<0.001)	–0.315*	–0.65	–0.24

β, standardized coefficient; BMI, body mass index; CI, confidence interval; DBP, diastolic blood pressure; MAP, mean arterial pressure; PP, pulse pressure; R², coefficient of determination; Z₁, the averaged impedance modulus corresponding to the first harmonic oscillations of cerebral blood flow velocity and carotid arterial pressure. Age, sex, and BMI were forced to enter sequentially. Stepwise method was used to enter hemodynamic variables.