EDAN elite V5 - O 2 Compensations; Effects of Humidity

Patient Monitor User Manual Monitoring AG
- 162 -
Blinking green light Zeroing in progress
Steady blue light Anesthetic agent present
Steady red light Sensor error
Blinking red light Check adapter
17.7 O
2
Compensations
The following models need O
2
compensation: IRMA AX+, ISA AX+. For the compensation
details, please refer to the following table.
O
2
Range Set O
2
Range
0 to 30 vol% Low
30 to 70 vol% Med.
70 to 100 vol% High
After settings, the interface will display a dialog box: Confirm to change the settings? And the
detailed settings are displayed under the warning. Click
Yes to confirm, and click No to cancel
the settings.
17.8 Effects of Humidity
The partial pressure and the volume percentage of CO
2
, N
2
O, O
2
and anesthetic agents depend on
the amount of water vapor in the measured gas. The O
2
measurement will be calibrated to show
20.8 vol% at actual ambient temperature and humidity level, instead of showing actual partial
pressure. 20.8 vol% O
2
corresponds to the actual O
2
concentration in room air with 0.7 vol% H
2
O
concentration (at 1013 hPa this equals for example 25 °C and 23% RH). The measurement of
CO
2
, N
2
O, and anesthetic agents (e.g. all gases measured by the IR-bench) will always show the
actual partial pressure at the current humidity level.
In the alveoli of the patient, the breathing gas is saturated with water vapor at body temperature
(BTPS).
When the breathing gas flows through the sampling line, the gas temperature will adapt to ambient
before reaching the gas analyzer. As the NOMO section removes all condensed water, no water will
reach the ISA gas analyzer. The relative humidity of the sampled gas will be about 95%.
If CO
2
values at BTPS are required, the following equation can be used:
where:
EtCO
2
= EtCO
2
value sent from ISA [vol %]
Pamb = Ambient pressure sent from ISA [kPa]
3.8 = Typical partial pressure of water vapor condensed between patient circuit and ISA [kPa]
EtCO
2
(BTPS) = EtCO
2
gas concentration at BTPS [vol%]
O
2
is assumed to be room air calibrated at a humidity level of 0.7 vol% H
2
O.