Stroke Volume Determination by Echocardiography

Abstract

Basic critical care echocardiography emphasizes two-dimensional (2D) findings, such as ventricular function, inferior vena cava size, and pericardial assessment, while generally excluding quantitative findings and Doppler-based techniques. Although this approach offers advantages, including efficiency and expedited training, it complicates attempts to understand the hemodynamic importance of any 2D abnormalities detected. Stroke volume (SV), as the summative event of the cardiac cycle, is the most pragmatic available indicator through which a clinician can rapidly determine, no matter the 2D findings, whether aberrant cardiac physiology is contributing to the state of shock. An estimate of SV allows 2D findings to be placed into better context in terms of both hemodynamic significance and acuity. This article describes the technique of SV determination, reviews common confounding factors and pitfalls, and suggests a systematic approach for using SV measurements to help integrate important 2D findings into the clinical context.

Keywords: critical care echocardiography; left ventricular outflow tract; pulsed-wave Doppler; stroke volume; ultrasound; velocity-time integral.