Ultrasound predictors of lung re-expansion following pleural effusion drainage

Abstract

<b>Background:</b> recent data have shown that the extent of displacement of collapsed lung inside effusion during breath-hold as seen by US predicts non-expandable lung (NEL) after drainage(1). This study aims to confirm this observation in patients undergoing medical thoracoscopy (MT) where full effusion drainage allows confident ascertainment of lung expandability. <b>Methods:</b> Patient undergoing MT were examined pre-procedure with US while sitting at the posterior axillary line. During breath-hold, US M-mode was used to quantify the displacement (D) of the collapsed lower lobe for several cardiac cycles. In addition, the echogenicity of collapsed lung and of the liver was quantified using US image with the help of a software (ImageJ). We hypothesised that the Lung/Liver echogenicity (LLE) can be a marker of lung stiffness (failure of lung de-aeration despite effusion) and hence predict NEL. Post procedure X ray was used to assess NEL. <b>Result:</b> 29 patients (59% females, mean age 49.6 years) were included; 52% right effusion. Median effusion volume drained was 2.1L.&nbsp; NEL was seen on post-MT X ray in 8/29 patients. The area under the curve (AUC) for using M-mode D to predict NEL was 0.48 (95% CI 0.25 to 0.71, p=0.86). A cut-off of &lt;1.7 mm had 62% sensitivity and 54% specificity. The AUC of LLE to predict NEL was 0.77 (95% CI 0.55 to 1, p=0.03). A cut-off of &gt;1.6 had 71% sensitivity and 83% specificity. <b>Conclusion:</b> Previously reported ability of M-mode D to predict NEL is exaggerated possibly due to reliance on data from procedures not achieving complete effusion drainage. The LLE is a potentially useful predictor of NEL that needs further validation. <b>Ref:</b> 1- Salamonsen et al. Novel use pleural Ultrasound. CHEST, 2014.