Table 1. Outcomes of comparison of BRS estimation methods by ordinary least products regression.

	supine				60° upright
parameters	Oxford-Phe	Oxford-Nitro	Oxford-Phe	Oxford-Nitro	Oxford-Phe	Oxford-Nitro	Oxford-Phe	Oxford-Nitro
	vs.	vs.	vs.	vs.	vs.	vs.	vs.	vs.
	TRS-BRS	TRS-BRS	TRS-Phe	TRS-Nitro	TRS-BRS	TRS-BRS	TRS-Phe	TRS-Nitro
a' (95% CI)	−3.9	−2.7	−4.1	−4.4	−0.5	0.4	−0.5	0.9
	(−10.3–0.3)	(−13.8–2.4)	(−8.7–2.3)	(−16.0–2.0)	(−4.2–2.2)	(−2.5–2.6)	(−3.5–1.7)	(−1.9–3.1)
b' (95% CI)	2.0	1.3	0.9	1.2	1.9	1.5	1.2	1.1
	(1.7–2.7)	(0.9–2.3)	(0.7–1.2)	(0.7–2.0)	(1.4–2.5)	(1.1–2.0)	(0.9–1.5)	(0.8–1.4)
proportional bias	yes	no	no	no	yes	yes	no	no
fixed bias	no	no	no	no	no	no	no	no

a',b' - coefficients in ordinary least products regression model y  =  a' + b'x; a' – (y axis) intercept, b’ – slope; proportional bias, if 95% confidence interval (CI) for b' does not include 1; fixed bias, if 95% CI for a' does not include 0.

Abbreviations: TRS-BRS, spontaneous baroreflex sensitivity (BRS) determined by trigonometric spectral analysis (TRS); TRS-Phe/TRS-Nitro, BRS determination during phenylephrine/nitroprusside infusion using TRS; Oxford-Phe/Oxford-Nitro, BRS determination by phenylephrine/nitroprusside infusion (modified Oxford method).