Clinical applicability of functional hemodynamic monitoring

Recently, increased interest in a more proactive use of monitoring technologies has emerged, using the response to the measured variables to a defined stress to unveil the physiological state of the subject. This entire field when applied to the assessment of cardiovascular state is referred to as functional hemodynamic monitoring. Within this context, we can define functional hemodynamic monitoring as the assessment of the dynamic interactions of hemodynamic variables in response to a defined perturbation [1]. Such dynamic responses result in emergent parameters of these commonly reported variables that greatly increase the ability of these measures to define cardiovascular state and predict response to therapy. At the present time, the primary types of functional hemodynamic monitoring for which clinical trials have shown clinical usefulness are related to predicting volume responsiveness and identifying occult cardiovascular insufficiency (compensated shock). The primary form of this approach, predicting volume responsiveness, was reviewed recently in this journal, so will only be briefly described in this article. However, like any form of monitoring parameter, its sensitivity and specificity improves if its pretest probability is higher. Thus, a fundamental concept often ignored by proponents of functional hemodynamic monitoring approaches is the integration of other clinical variables, such as the clinical condition, serum lactate levels, etc., a priori into the decision analysis of cardiovascular instability and its response to therapy. In essence, functional hemodynamic monitoring, though profoundly insightful in its values, is only another parameter that needs to be integrated into the greater view of patient care if its use is to realize its full potential.A primary resuscitation question is whether the patient will increase their cardiac output in response to intravascular volume infusion. Volume responsiveness has been arbitrarily defined as ≥15% in card