ABSTRACT
Hemodynamic instability leading to shock is defined as a situation where oxygen transport is inadequate to meet oxygen requirements. An understanding of the mechanism(s) of reduced cardiac output (CO), a determinant of oxygen transport, is crucial in order to initiate appropriate therapy to manage shock. The concepts of venous return and the pressure-volume relationship, popularized by Guyton et al.,1 combined with bedside ultrasound (US) appears to be the most comprehensive way to understand the state of shock.2,3 If the patient in shock is unresponsive to general resuscitation measures, bedside US examination of the heart, lung, and abdomen, using either a transthoracic or a transesophageal approach, is performed. Ultrasound can
be useful to: (1) determine the mechanism(s) of shock, (2) establish the etiology, and (3) evaluate the response to therapy. This chapter provides a diagnostic approach to shock based on the integration of non-echocardiographic and echocardiographic variables.
