15-1 
15 Monitoring Cardiac Output 
(for uMEC12/uMEC15) 
 
15.1 Introduction 
The cardiac output (C.O.) measurement invasively measures cardiac output and other 
hemodynamic parameters using the right heart (atria) thermodilution method. A cold solution 
of known volume and temperature is injected into the right atrium through the proximal port 
of a pulmonary artery (PA) catheter. The cold solution mixes with the blood in the right 
ventricle and the change in blood temperature is measured with a thermistor at the distal end 
of the catheter in the pulmonary artery. The temperature change is displayed as a curve in the 
C.O. split screen, and the monitor calculates the C.O. value from this curve. The C.O. value 
is inversely proportional to the area under the curve. As cardiac output varies continuously, a 
series of measurements must be carried out to achieve a reliable C.O. average value. Always 
use the average of multiple thermodilution measurements for therapy decisions. The monitor 
is capable of storing 6 measurements. 
 
 WARNING 
z  C.O. monitoring is restricted to adult patients only. 
 
 
15.2 Understanding the C.O. Display 
The C.O. measurement is displayed on the monitor as numeric C.O., C.I. and TB in the C.O. 
parameter window as shown below. To enter the [C.O. Setup] menu, select the C.O. 
parameter window. 
 
 
(1) Cardiac output 
(2)  Time at which the C.O. average is calculated 
(3) Cardiac index 
(4) Blood temperature 
 
(1) 
(3) 
(4) 
(2)