Background: Pleural effusion may be a result of a primary pulmonary illness. It also can be the pleural manifestation of numerous of diseases that primarily affect other organs. Quantification of pleural effusion is of great value in clinical practice, as it usually guides the plan of management. Chest ultrasound (U/S) is one of the helpful non-invasive means in estimating pleural fluid volume.
Objective: To correlate the U/S estimated volumes of pleural fluid calculated by studied formulae, with the actual effusion volume, and to identify the most accurate formula in quantifying the pleural fluid volume.
Patients and Methods: This prospective cross-sectional study was carried out in the department of Chest, Bab Al-sha'reia University Hospital, during the period from October 2019 to September 2020, and included forty patients with clinical and radiological diagnosis of pleural effusion. Ultrasound estimation of the amount of pleural effusion was done using 4 different formulae, followed by full pleural drainage through either simple aspiration or tube thoracostomy. Lastly, the ultrasonographically estimated fluid volumes were then compared to the actually drained fluid volume.
Results: The supine formulae showed excellent correlation with the drained pleural fluid volume, with Pearson correlation coefficient(r) = 0.9607 and 0.9602 for Eibenberger and Balik formulae respectively (p-value <0.0001). On the other side, the erect formulae were found to have reasonable correlations with the drained volume, with r= 0.4017 (p-value= 0.0102) and 0.5729 (p-value <0.0001) for Goecke1 and Goecke 2 respectively. All studied formulae failed to quantify the pleural effusion volume accurately when comparing its estimated volume to the actually drained fluid volume.
Conclusion: The 4 studied formulae had good correlations with the actually drained volume. However, supine formulae were better than erect formulae.