Positive and Quantitative Diagnosis of Pleural Effusions by Thoracic Ultrasonography in Patients With Acute Respiratory Failure in the Emergency Department

Acute respiratory failure (ARF) is a frequent reason for consulting in the Emergency Department (ED) and one of the major clinical problems prompting admission in intensive care unit. In the ED, evaluation of an ARF is mainly based on clinical examination and frontal chest x-ray performed to the patient bedside. This practice has a limited diagnostic capacity due to a lack of specificity of clinical and radiological semiology, especially in the polypathological patient. Thoracic ultrasonography provides morphological information regrouped as a syndrome (interstitial syndrome, alveolar condensation, pneumothorax) and allows the identification of pleural effusions (PE). The PE diagnosis is easy, quick, and relies on two-dimensional ultrasound imaging. Compared to CT scan, which remains the reference examination although ill-suited in the context of emergency, thoracic ultrasonography has a sensitivity and specificity greater than 90% for pleural liquid (PL) diagnosis. In addition, thoracic ultrasonography is used to assess the volume of PL, determine its nature and guide the pleural puncture with higher performance than chest x-ray. The semi-quantitative evaluation of PEs has been validated in patients with mechanical ventilation hospitalized in intensive care unit. On the other hand, few data on the prevalence and quantification of PL for hospitalized patients in ED for an ARF are currently available. Thus, the objective of this study is to evaluate the prevalence and severity of the PL identified by thoracic ultrasonography in patients admitted to the ED for an ARF by emergency physicians with ultrasound skills recommended by the French Society of Emergency Medicine.