الفهرس | Only 14 pages are availabe for public view |
Abstract There has been a several modifications in the management of septic shock. Studies such as the early goal-directed therapy (EGDT) advocated for aggressive fluid management guided by static measures such as the central venous pressure (CVP). Recently, several studies have demonstrated that aggressive resuscitation of septic shock patients as well as an overall positive fluid balance can be harmful and can lead to worst outcomes. So, it is important to avoid excessive fluid administration in such cases. Depending on static measurements such as CVP to predict volume responsiveness has been unreliable by several studies. In order to predict the response of cardiac output to fluid infusion, the passive leg raising (PLR) test has been validated. It consists of lifting the legs passively at 45°and moving the trunk down horizontally, starting from a semi-recumbent position. By transferring a consistent amount of venous blood from the legs and the splanchnic compartment towards the intra-thoracic compartment, it increases the mean systemic pressure, the cardiac preload and consequently cardiac output in the case of preload responsiveness of both ventricles. However, it must be coupled with a direct and real-time measurement of cardiac output, which is often invasive. The decision to give fluids must be guided by a reliable prediction of fluid responsiveness as around 50% of patients respond to fluid administration by increasing cardiac output. So, recent research started to study non-invasive maneuvers for assessing volume responsiveness such as the inferior vena cava (IVC) ultrasound evaluation, as well as more advanced Doppler applications such as esophageal Doppler monitoring looking at changes in aortic flow time to guide fluid therapy. Moreover, some studies have looked at the left ventricular outflow tract (LVOT) velocity time integral (VTI) change with either a passive leg raise or a fluid bolus as a measure of volume responsiveness and found it to be specific in predicting fluid responsiveness. Acquiring an appropriate apical five-chamber view and getting an adequate window of the LVOT can be challenging. Novice emergency physicians (EP) are taught to identify the apical 4-chamber and then tilt the ultrasound upward and slightly counterclockwise to open the 5th chamber, the aorta. The inability of getting an adequate apical-5 chamber can underestimate patients’ VTI values. Given that the majority of EPs are comfortable with apical-4 views and carotid duplex, we sought to investigate the sensitivity and specificity of mitral valve (MV) velocity time integral (VTI) as a non-invasive marker of volume responsiveness. |