Correlation of thermodilution-derived extravascular lung water and ventilation/perfusion-compartments in a porcine model

Abstract

Purpose

This study examines the correlation between the transpulmonary thermodilution derived extravascular lung water content (EVLW) and the ventilation/perfusion-distribution ($\dot{V}/\dot{Q}$) measured by multiple inert gas elimination (MIGET) in a porcine model.

Methods

$\dot{V}/\dot{Q}$ measured by micropore membrane inlet mass spectrometry-MIGET (MMIMS-MIGET) and EVLW were simultaneously measured in twelve pigs in the heathy state, with impaired gas exchange from repetitive lung lavage and after 3 h of ventilation. The relationship between $\dot{V}/\dot{Q}$ compartments and EVLW was analysed by linear correlation and regression.

Results

Considerable increases in EVLW and $\dot{V}/\dot{Q}$ mismatching were induced through the lavage procedure. Significant correlations between the EVLW and the $\dot{V}/\dot{Q}$ fractions representing pulmonary shunt and low $\dot{V}/\dot{Q}$ were found. Perfusion to the normal $\dot{V}/\dot{Q}$ regions was inversely correlated to the EVLW.

Conclusions

Increased EVLW is associated with increased low $\dot{V}/\dot{Q}$ and shunt, but not equal to pulmonary shunt alone. Beneath true shunt EVLW can also be associated with low $\dot{V}/\dot{Q}$ regions.