Table 2. Linear regression analyses for factors associated with the cerebrovascular compliance markers.

MCA PI a	B (95% CI)	β	P
	0.343 (0.169–0.516)		<0.001**
Age (year)	0.007 (0.004–0.009)	0.480	<0.001**
MRIR b	B (95% CI)	β	P
	1.002 (0.984–1.020)		<0.001**
Stage N3 (%)	-0.001 (-0.002–0.000)	-0.210	0.030*
Respiratory distress index (/h)	0.003 (0.001–0.005)	0.226	0.021*

^aR² = 0.230 and P<0.001 and

^bR² = 0.247 and P<0.001 for the linear regression equation.

B: unstandardized coefficient, β: standardized coefficient, CI: confidence interval, MCA: middle cerebral artery, PI: pulsatility index, and MRIR: mean middle cerebral artery resistance index ratio.

*P<0.05 and

**P<0.01.