Using ventilation-induced aortic pressure and flow variation to diagnose preload responsiveness

Abstract

The recent literature has documented that both arterial pulse pressure [1] and left ventricular stroke volume variations [2] induced by positive-pressure ventilation are sensitive and specific markers of preload responsiveness. The greater the degree of flow or pressure variation over the course of the respiratory cycle for a fixed tidal volume, the more likely the subject is to increase their cardiac output in response to a volume challenge and the greater that increase may be. Slama et al. [3] report in this issue that in a rabbit model of graded hemorrhage measuresof aortic flow variation during positive-pressureventilation cardiac output will increase in response to volume expansion. Furthermore