Table 1 Pulse pressure-derived algorithms tested

Windkessel

(Erlanger and Hooker [31], 1904)

k * (SBP-DBP) * HR

Windkessel with RC decay

(Bourgeois et al. [32], 1976)

k * (MAP/T) * ln(SBP/DBP) * HR

Liljestrand-Zander

(Liljestrand and Zander [33], 1928)

k * (SBP-DBP)/(SBP + DBP) * HR

Herd

(Herd et al. [34], 1966)

k * (MAP-DBP) * HR

Pressure root-mean-square

(Jonas and Tanser [35], 2002)

$\mathsf{\text{k}}*\sqrt{{\int }_{\mathsf{\text{T}}}{\left(\mathsf{\text{ABP}}\left(\mathsf{\text{t}}\right)-\mathsf{\text{MAP}}\right)}^2\mathsf{\text{dt}}}*\mathsf{\text{HR}}$

Systolic area

(Jones et al. [36], 1959; Verdouw et al. [37], 1975)

$\mathsf{\text{k}}*{\int }_{\text{sys}}\mathsf{\text{ABP}}\left(\mathsf{\text{dt}}\right)*\mathsf{\text{HR}}$

Systolic area with correction

(Warner et al. [38], 1953; Kouchoukos et al. [39], 1970)

$\mathsf{\text{k}}*{\int }_{\text{sys}}\mathsf{\text{ABP(dt)}}*\left(1+\frac{\text{Tsys}}{\text{Tdia}}\right)*\mathsf{\text{HR}}$

Corrected impedance

(Wesseling et al. [40], 1983; Rauch et al. [41], 2002)

$\text{k}*(163+\text{HR}-0.48*\text{MAP)*}{\displaystyle {\int }_{\text{sys}}\text{ABP}(\text{dt})*\text{HR}}$