Pulmonary consolidation alters the ultrasound estimate of pleural fluid volume when considering chest drainage in patients on ECMO
Abstract
The estimation of pleural fluid volume evaluated by bedside chest ultrasound (CUS) helps to decide on pleural drainage. The method of multiplying the maximum transverse pleural separation at the base of the lung in millimetres by 20 has been formulated and independently verified in mechanically ventilated patients.
The method presumes an aerated lung floating in pleural fluid with expected compression of the basal segments and largest pleural separation at the lung base. The calculation may fail in extensively consolidated and less buoyant lungs encircled by pleural fluid which may be found in severe ARDS treated, in addition to IPPV, with the extracorporeal membrane oxygenation (ECMO).
The degree of lung consolidation evaluated as alveolo-interstitial syndrome can also be diagnosed and quantified by a bedside ultrasound. We tested the hypothesis that in patients with extensive lung consolidation with scores 3 (coalescent B lines) to 4 (consolidation) in all lung regions, the established method of estimating pleural fluid volume may produce a large prediction error.
Multiple pleural separation measurements may be more useful to provide an accurate quantification of pleural fluid.