93
Chapter 16 CO
2
Measuring
16.1 Introduction
The device adopts infrared absorption technology to measure the CO
2
concentration in the patient's breathing airway.
The principle is that the CO
2
molecules can absorb the infrared energy with specific wavelength, and the amount of
energy absorbed is directly related to the CO
2
concentration. When the infrared light emitted by the infrared light source
penetrates the CO
2
sample, part of the energy will be absorbed by the CO
2
in the gas. On the other side of the infrared
light source, use a photodetector to measure the residual infrared light energy which will be converted into the electrical
signal. Comparing and adjusting the electrical signal and infrared light energy to accurately reflect the CO
2
concentration in the gas sample.
CO
2
measurement methods:
1. Mainstream
Install the CO
2
sensor to the airway joint of respiratory system connected to the patient directly.
2. Sidestream
The respiratory gas in the patient's respiratory airway was sampled using a constant sampling flow rate and
analyzed by a built-in CO
2
sensor.
CO
2
measurement can provide:
1. One-channel CO
2
waveform.
2. EtCO
2
:
End Tidal carbon dioxide, CO
2
value measured in the end of respiratory phase
3. InsCO
2
: Inspired Minimum CO
2
4. AwRR: Air Way Respiratory Rate, respiratory times per minute.
16.2 Safety information
WARNING
l
Don’t use the device in the environment with flammable anesthetic gas.
l
The device can only be operated by personnel having taken professional training and familiar with this
manual.
l
Notice and prevent the electrostatic discharge (ESD) and electromagnetic interference (EMI) with other
instruments.
l
When placing sensor cables or tubes, avoid intertwining or squeezing each other.
l
When the CO
2
module is wet or condensed, do not use it.
l
Do not connect the exhaust pipe to the ventilation duct.
l
The device and its accessories are free of latex.
l
If the patient can not tolerate the sampling rate of 50 ml / min ± 10 ml / min, please stop using it.
NOTE:
l
When you do not use CO2 monitoring function, it is suggested to set “ WORK MODE” to “STANDBY”.
