Comparison of quantitative computed tomography analysis and single-indicator thermodilution to measure pulmonary edema in patients with acute respiratory distress syndrome

OBJECTIVE To compare quantitative computed tomography (CT) analysis and single-indicator thermodilution to measure pulmonary edema in patients with acute respiratory distress syndrome (ARDS). METHOD Ten patients with ARDS were included. All underwent spiral CT of the thorax for estimating gas content of lung (GVCT), tissue volume of lung (TVCT), tissue volume index (TVI), mean radiographic attenuation (CTmean) for the whole lung and gas-to-tissue ratio (g/t). Pulmonary thermal volume (PTV) and extravascular lung water index (ELWI) were determined by the PiCCO plus system. CT or single-indicator thermodilution variables were correlated with respiratory system compliance (Crs), PaO2/FiO2, and Acute Physiology And Chronic Health EvaluationII (APACHE II) and Sequential Organ Failure Assessment (SOFA) scores. RESULTS 1) TVCT and PTV were positively correlated (r =0.8878; P = 0.0006; equation of regression line: PTV = 1.0793 × TVCT + 179.8) as were TVI and ELWI (r =0.9459; P < 0.0001; equation of regression line: ELWI = 1.4506 × TVI-8.7792). The bias between TVCT and PTV as well as TVI and ELWI was -277 ± 217 and 0.62 ± 4.56, respectively. 2) ELWI and CT distribution of lung-tissue compartments were not correlated. 3) CT or single-indicator thermodilution variables were not correlated with Crs, PaO2/FiO2 or APACHE II or SOFA score. CONCLUSION Quantitative CT analysis and single-indicator thermodilution showed good agreement in measuring pulmonary edema.