Fluke Biomedical MPS450 - Manual (Page 68)

MPS450
Operators Manual
2-36
Cardiac Output
Cardiac output is a term encompassing blood flow, pulse rate, and other vascular-related
elements. Of the entire circulatory system, cardiac output is arguably the most important
single factor for health since it controls the degree of blood being received by every other
tissue in the body. Diseases of the heart can cause a decrease of cardiac output, leading to
a condition of insufficient nutrition for the body cells. Cardiac output is expressed as the
measure of blood pumped out of the heart each minute, also called the heart-minute
volume (HMV).
One method of determining cardiac output is to measure the transference of heat in the
blood through a method called thermodilution. Thermodilution is the measurement of the
temperature change caused by the injection into the heart of a series of cold or room-
temperature solutions (such as a saline solution) into the heart. A thermistor (as integrated
into the distal lumen port of a Swan-Ganz catheter) measures the average change in blood
temperature. From this information, a determination can be made as to ventricular blood
volume and cardiac output.
The MPS450 simulates blood cooling, as the result of an injectate, to below-normal
temperatures. On most monitors, the blood temperature curve is in the positive direction,
even though the blood is cooling. Following the simulated cardiac-output test, ECG
reverts to normal sinus rhythm at 80 BPM.
To simulate cardiac output, use the cardiac-output adapter box, which is supplied as part
of the cardiac-output option. (See the section in the “Setting Up for a Cardiac-Output
Test” section later in this chapter.)
Setting Up For a Cardiac-Output Test
Action
1. Configure the cardiac-output monitor to the settings listed in Table 2-28, which are
compatible with the MPS450 simulation:
Table 2-28. Cardiac-Output Monitor Settings
Variable Setting
CATHETER TYPE / SIZE: Baxter Edwards, 93a-131-7f
CALIBRATION COEFFICIENT: 0.542 for 0 ° C injectate; 0.595 for 24 ° C injectate
INJECTATE VOLUME: 10 cc
INJECTATE TEMPERATURE: 0 ° C or 24 ° C
2. Connect the cardiac-output adapter box to the CO/TEMP connector on the right-side
panel of the MPS450.
3. Connect the BT thermistor cable from the cardiac-output monitor to the smaller 4-pin
connector on the cardiac-output adapter box. This is the blood-temperature-
simulation line directly wired to the MPS450.
4. Connect the injectate-temperature cable from the cardiac-output monitor to the bigger
4-pin switchcraft connector on the cardiac-output adapter box. This line is wired to
the trimpot on the front panel of the CO adapter box, enabling the resistance to be set
correctly to either 0 ° C or 24 ° C, as displayed on the CO monitor.
5. With the MPS450 turned on, the blood-temperature indicator on the CO monitor
should read approximately 37 ° C.
6. Turn the trimpot on the CO adapter box until the injectate-temperature (IT) sensor