Mindray PM-9000, Operation Manual

Page: 279 / 378

CO
2
Monitoring
17-3
17.2 Mindray CO
2
Module
NOTE
z
This section is only applicable to a monitor equipped with a Mindray CO
2
module.
17.2.1 Principles of Operation
WARNING
z
The CO
2
module should be protected against crash and vibration.
z
Our CO
2
module is only applicable to pediatric and adult patients, but
not to neonate patients.
z
Inaccurate measurement may occur when the monitor is operating in an
environment of excessively high CO
2
content (>0.5%).
The monitor adopts our sidestream CO
2
module. The measurement of this module is
based on the feature that the CO
2
molecule absorbs infrared ray. The measurement
procedure is as follows : send the CO
2
to a measurement chamber inside the module
through the airway system, and then irradiate 4.26um infrared ray at one side of the
chamber and use the sensor to measure the attenuation degree of the received
infrared ray at the other side. Since the attenuation degree of the infrared ray is
proportional to the concentration of CO
2
, the CO
2
concentration is calculated. The
measured CO
2
concentration is thereafter converted into the partial pressure under
the same temperature and pressure, and then displayed.
The relation between the partial pressure and the CO
2
concentration is given below:
CO
2
partial pressure (mmHg)=
CO
2
concentration (%)×Pamp (ambient pressure, mmHg)/100
CO
2
partial pressure (kPa)= CO
2
partial pressure (mmHg)/7.5