User's Manual

Contents
19-3
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Setup Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Display Detail. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Entering the Computational Constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Entering Patient Height/Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Measuring Cardiac Output. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Averaging Cardiac Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Clearing Cardiac Output Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Storing Cardiac Output Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Stopping Curve Drawing and Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Selecting Index Normalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Displaying Cardiac Index and Cardiac Output Values. . . . . . . . . . . . . . . . . . . . 8
Displaying Calculations Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Editing Vital Sign Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
View Additional Table Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Recording Cardiac Output Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Cables and Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Cardiac Output Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Cardiac Output
Overview
Cardiac output (CO) monitoring enables you to evaluate the patient’s fluid status
and the pumping ability of the heart, as well as calculate and display various
hemodynamic values.
Cardiac output is calculated by the thermodilution technique using a variation of
the Stewart-Hamilton formula. Thermodilution involves injecting a cooled fluid
(injectate) through a flow-through housing into an intravascular catheter. The
catheter delivers the injectate directly to the right atrium and monitors the
temperature downstream from the delivery site at the pulmonary artery.
Cardiac output is determined by measuring the change in blood temperature
downstream from the delivery site with respect to time. The change in
temperature is inversely proportional to the flow of blood through the right heart. If
the flow is large, the volume of blood that the injectate mixes with is large as well,
so the monitor detects a small change in temperature. When a smaller flow of
blood is diluted by the same volume of injectate, the change in temperature is
larger. The injectate has a larger influence on the temperature as measured in the
pulmonary artery.
The system displays cardiac output by plotting a curve for each injection. The
vertical axis of the curve represents temperature and the horizontal axis
represents time.
Spacelabs Medical’s cardiac output monitoring automatically captures vital sign
values at the moment each CO curve is completed. This data is used to produce
hemodynamic calculations.