Pulse pressure analysis: to make a long story short

Pulse pressure analysis algorithms are commonly used to measure cardiac output and to allow for the rational titration of therapy in critically ill patients. The ability of these algorithms to accurately track changes in stroke volume (and cardiac output) is thus very important. Most of the currently available algorithms can provide robust data so long as there is no fundamental change in the vasomotor tone (arterial compliance or impedance). If the tone changes significantly, for instance with vasodilatation or vasoconstriction, then the data become less robust. For this reason, unless there is a mechanism for compensating for changes in vasomotor tone, these algorithms are best used only over short time periods in order to get the most accurate and precise data on changes in cardiac output.