Using ultrasound lung comets in the diagnosis of high altitude pulmonary edema: fact or fiction?

High altitude pulmonary edema is a life-threatening condition that remains a concern for climbers and clinicians alike. Within the last decade, studies have shown ultrasonography to be valuable in the accurate diagnosis of a variety of lung pathologies, including cardiogenic pulmonary edema, pleural effusion, pneumothorax, and lung consolidation. Recently, studies conducted in remote areas have demonstrated that ultrasound lung comets can be used as a measure of subacute pulmonary edema and high altitude pulmonary edema in climbers ascending to altitude. This clinical review article provides an overview of lung ultrasonography and its relevance as a diagnostic aid to respiratory pathology. In addition, we describe a standardized technique for identifying ultrasound lung comets and its utility in recognizing the presence of extravascular lung water, as well as the results of studies that have used this approach at sea level and high altitude.