Simplified lung ultrasound protocol shows excellent prediction of extravascular lung water in ventilated intensive care patients

IntroductionUltrasound of the lung and quantification of B-Lines was recently introduced as a novel tool to detect overhydration. In the present study we aimed to evaluate a four region protocol of lung ultrasound to determine the pulmonary fluid status in ventilated patients in the intensive care unit.

Methods: Fifty patients underwent both lung ultrasound and transpulmonary thermodilution measurement using the PiCCO-System.

An ultrasound score based on number of single and confluent B-Lines per intercostal space was used to quantify pulmonary overhydration.To check for reproducibility the ultrasound pictures were blinded and reassessed by two different intensivists and classified using the same scoring system. Results were compared to other methods of evaluating hydration status, including extravascular lung water index (EVLWI) and intrathoracic blood volume index calculated from transpulmonary thermodilution measurements.

Moreover, chest radiographs were assessed regarding signs for pulmonary overhydration and categorized based on a numeric rating scale.

Results: Lung water assessment by ultrasound using a simplified protocol showed excellent correlation with EVLWI over a broad range of lung hydration grades and ventilator settings. Correlation of chest radiography and EVLWI was less accurate.

No correlation whatsoever was found with central venous pressure measurement.

Conclusion: Lung ultrasound is a useful non-invasive tool to predict hydration status in mechanically ventilated patients. The four region protocol is time saving, correlates well to transpulmonary thermodilution measurements and performs markedly better than chest radiography.