I am trying to understand why should anyone use Flotrac/Vigileo at all ? From what i understand, it calculates stroke volume based on arterial pressure wave contour analysis. All other variables including CO/CI/SVR are derived from stroke volume, HR, CVP and MAP. The basic assumption is that pulse pressure is a poor man's stroke volume. Is pulse pressure or PPV already not enough to guess about hypovolemic/vasodilatory/cardiogenic shock, if we are going to believe in the CO/CI based on these assumptions. We can argue that it also provides SVV and global EF. I can get global EF in a much more reliable way from a bedside ECHO.
Also, most of the patients come to the unit having gotten already 3-4 liters of iv fluids. How does fluid responsiveness matter at that time ? How can we say fluid responsiveness means fluid tolerant and that we shouldn't be starting vasopressors early, in which case the flotrac is not reliable anyways. Even if SVV is more than 13%, How can we say that we shouldn't be using vasopressors/inotropes to improve cardiac output, if the absolute CO/CI numbers matter at all. Its frustrating to see people using these monitors to give more fluids based on SVV, even when they are in 30-40 liters positive fluids balance. The most frequent argument that i hear is that those patients are intravascularly depleted, which makes me laugh, mad and depressed about the standard of care that these patients are getting. Of course, not everybody is the same though.
Whats your experience with other monitors ? Any other thoughts would be highly appreciated.