Velocity-Time Integral: A Bedside Echocardiography Technique Finding a Place in the Emergency Department

Background: Point-of-care ultrasound is a fundamental tool in the emergency department when managing the critically ill patient. Determining a patient's hemodynamic status at the bedside can better guide resuscitation efforts. The left ventricular outflow tract velocity-time integral (VTI) is a validated, noninvasive, and rapidly acquired echocardiographic measurement that is analogous to stroke volume.

Discussion: VTI can be used to determine fluid responsiveness and to risk stratify patients, particularly in pulmonary embolism, heart failure, and sepsis. Emergency physicians with limited experience can successfully measure VTI in a timely and accurate manner. However, VTI measurement is not commonly taught in emergency medicine residency and, as a result, it is an underused tool.

Conclusions: VTI is an objective tool for clinicians to assess the hemodynamic status of critically ill patients. Understanding the acquisition of VTI and proper application in the context of the patient's history, clinical examination, and other bedside ultrasound findings, should be reviewed within the emergency medicine residency ultrasound curriculum. This article provides a simple four-step protocol, as well as bedside applications and potential limitations for VTI in the ED.