Comparison of Double Indicator Thermodilution Measurements of Extravascular Lung Water (EVLW) with Radiographic Estimation of Lung Water in Trauma Patients

The availability for clinical use of a simple reliable method of determining extravascular lung water (EVLW) provided us with the opportunity to evaluate the accuracy of the plain chest roentgenogram in estimating EVLW in patients with severe trauma. Twelve patients who sustained blunt trauma in motor vehicular accidents were studied. Interval measurements of EVLW were made utilizing the thermal-green dye, double-indicator dilution technique and the results compared in a blind manner to estimation of lung water content on standard chest roentgenograms. The results indicate a significant correlation was present when EVLW was compared to roentgenographic density grade. Considerable overlap existed in quantitative EVLW content between radiographic grades except when extensive consolidation was present on the chest radiograph which was associated with EVLW measurements of greater than 10 ml/kg. The random comparison of a change in measured EVLW with a change in radiographic density indicated that there were opposite changes in 23% of the comparisons. However, in selected patients with progressive improvement (decrease) in EVLW or gradual deterioration (increase) in EVLW over time there was good correlation between improvement or deterioration in the chest radiographic appearance with the decrease or increase in EVLW. There is some ability to ascertain in trauma patients interstitial fluid accumulation from chest radiographs, but attempts at quantitation would be fraught with considerable error.