Which condition can cause a false low measurement when using a pulmonary artery catheter for cardiac output monitoring?

The presence of tricuspid regurgitation can lead to inaccuracies in the measurement of cardiac output when using a pulmonary artery catheter. In this condition, the backward flow of blood from the right ventricle into the right atrium during systole can cause an apparent decrease in the effective stroke volume. This results in altered hemodynamics and can create a situation where the calculated cardiac output appears lower than the actual value.

When the blood flow is disrupted due to tricuspid regurgitation, the thermodilution method used for measuring cardiac output can yield misleadingly low results. The falsely low measurement occurs because the regurgitant flow can reduce the volume of blood that effectively reaches the pulmonary artery, thus diminishing the amount of thermal indicator seen by the catheter.

Understanding the effects of tricuspid regurgitation is crucial for clinicians, as recognizing this potential for false readings can prompt them to consider other factors or reevaluate the patient's hemodynamic status.