New in the MICU, coming off a telemetry floor and trying to learn some of the hemodynamic parameters that we use. I'm okay with CO and such, but I am having trouble with stroke volume variance. We use presep catheters -- not swans in this icu -- and then are in a subclavian vein like a central line.
The problem I am having is this: I know now that SVV is higher when the patient is drier. Okay, fine. I can roll with that, but I was wondering the whys and hows of this -- the pathopysiology so to speak. I can get that stroke volume would be less with an "empty tank", but why would the stroke volume vary from beat to beat . . . or is it from some "normalized" stroke volume . . . I don't know. I know how to read the number, but I like to know why. Anybody out there have some helpful explanations -- or point me in the right direction.