Emerging applications of clinical ultrasonography.

In this work, we introduce the numerous emerging areas and frontiers in the use of point-of-care ultrasonography. Of these, we review the following three: 1) the use of clinical ultrasonography in infectious and tropical diseases (we address its usefulness in the diagnosis and follow-up of the main syndromes, in tropical diseases, and in areas with scarce resources); 2) the usefulness of clinical ultrasonography in the assessment of response to volume infusion in severely ill patients (we review basic concepts and the main static and dynamic variables used for this evaluation); and 3) the use of clinical ultrasonography in the assessment of muscle mass in elderly patients with primary sarcopenia (we review the main muscles and measurements used for it).