Surgery>>>>>Physiologic Monitoring of the Surgical Patient
Question 10#

Noninvasive methods of measuring cardiac output:

A. Allow for continuous measurement of Q_T
B. Show excellent correlation with Q_T as measured by thermodilution
C. Have rarely been adopted into clinical practice due to the increased training burden
D. Have similar complication rates as the use of a pulmonary artery catheter

Correct Answer is A

Comment:

Noninvasive methods of monitoring cardiac output include impedance cardiography and pulse contour analysis among others. Impedance cardiography is attractive because it is noninvasive, provides a continuous readout of Q_T, and does not require extensive training. However, measurements of Q_T obtained by impedance cardiography are not sufficiently reliable to be used for clinical decision-making and have poor correlation with thermodilution. Measurements of Q_T based on pulse contour monitoring are comparable in accuracy to standard PAC thermodilution methods, but are less invasive since transcardiac catheterization is not needed. The use of pulse contour analysis has been applied using noninvasive photoplethysmographic measurements of arterial pressure. However, the accuracy of this technique has been questioned and its clinical utility remains to be determined.