Welch Allyn 1500 Patient Monitor v.1.4.X - User Manual User Manual
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Monitoring and Measurements
Welch Allyn 1500 Patient Monitor
The default settings are in bold.
Parameter
Description
Mode
Auto
, manual. In auto mode the unit monitors the blood temperature and
indicates that a measurement can be commenced only when the temperature
is stable.
In manual mode, the user monitors starts the measurement at any time.
Computation constant
Between 000 and 999 (starting figure 400). This is a constant based on the
temperature coefficient of the catheter, temperature and volume of the
injectate, and catheter dimensions.
The formula used is as follows:
Where:
1.08
= density times specific heat (5% dextrose / blood)
C
t
= catheter thermal loss coefficient (specified by the catheter
manufacturer)
60 =
seconds
V
I
= volume of the injectate
1000
= conversion factor (cubic centimeters to liter)
Note: The C
t
value specified by the manufacturer, will differ according the
temperature of the injectate solution and separate C
t
values will be stated for
different temperature ranges, for example 0
o
to 5
o
, 19
o
to 22
o
, and 23
o
to 25
o
.
Since all factors are constants except the injection volume and the injection
temperature, many manufactures will specify the computation constant CC for
specific volumes and temperature range instead of the thermal loss coefficient
C
t
in their instruction leaflet. This can be entered directly.
Display parameter
CO
, CI. Measurement shown as cardiac output (liters per minute) or cardiac
index (cardiac output / body surface area (m
2
)). For CI the patient data must
have been entered.
Caution
It is essential that the computation constant is entered correctly so
that the monitor knows the volume and temperature range of the injectate, and
the thermal loss of the catheter. Inaccurate results will be obtained if the
computation constant is not correct.
CC =
1.08 * C
t
* 60 * V
I
1000