Table 4 Results of the linear regression between parameters of inferior vena cava and invasively measured central venous pressure

Inferior vena cava systolic velocity

0.051

Inferior vena cava systolic velocity time integral

0.344

Inferior vena cava diastolic velocity

0.061

Inferior vena cava diastolic velocity time integral

0.203

Inferior vena cava reversal velocity

0.774

Inferior vena cava reversal velocity time integral

0.643

Inferior vena cava systolic to diastolic velocity ratio

Inferior vena cava minimum size

0.0702

Inferior vena cava maximum size

0.031

Central venous pressure = 9.04 + 0.23 × IVC max

Body surface area-indexed inferior vena cava minimum size

0.812

Body surface area-indexed inferior vena cava maximum size

0.602

Inferior vena cava collapsibility index

0.702

Inferior vena cava distensibility index

0.612

Inferior vena cava minimum size to descending aorta minimum size ratio \(\left( {\frac{{{\text{IVC}}_{\min } }}{{{\text{DAO}}_{\min } }}} \right)\)

0.004

Central venous pressure = 8.51 + 2.39 × \(\frac{{{\text{IVC}}_{\min } }}{{{\text{DAO}}_{\min } }}\)

Inferior vena cava maximum size to descending aorta maximum size minimal dimension ratio \(\left( {\frac{{{\text{IVC}}_{\max } }}{{{\text{DAO}}_{\max } }}} \right)\)

 < 0.001

Central venous pressure = 7.92 + 2.82 × \(\frac{{{\text{IVC}}_{\max } }}{{{\text{DAO}}_{\max } }}\)