Role and importance of ultrasound lung comets in acute cardiac care

Lung ultrasonography is an emerging, user-friendly and easy-to-use technique that can be performed quickly at the patient's bedside to evaluate several pathologic conditions affecting the lung. Ultrasound lung comets (ULCs) are an echographic sign of uncertain biophysical characterisation mostly attributed to water-thickened subpleural interlobular septa, but invariably associated with increased extravascular lung water. ULCs have thus been proposed as a complementary tool for the assessment and monitoring of acute heart failure and are now entering into statements in international recommendation documents. Adding lung ultrasonography to conventional echocardiography allows for performing an integrated cardiopulmonary ultrasound examination, and this is an important opportunity for the cardiologist. The technique allows the simultaneous gathering of considerable information about the heart and the lungs to investigate acute and chronic cardio-pulmonary conditions within a non-invasive, radiation-free, single-probe, all-in-one examination. We have here reviewed the pertinent literature on the physical origin of ULCs and on their role and importance in intensive and acute cardiac care settings. We also here propose a new algorithm aimed at implementing evaluation in the diagnostic work-up of patients with suspected acute heart failure.