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External Sidestream ETCO2 Module

It is a kind of Low Flow Side stream Module. The new design is easier to match with monitor or anesthesia machine. The user just need to fix a 8-pin Lemo socket in the panel of the host, and connect the power of the host and dataline to an electrical outlet. This design will make maintenance much convenient. The output parameters include real time CO2 concentration, respiration rate, end-tidal CO2, inspired CO2, The C300 module includes a miniature CO2 sensor, barometric pressure transducer, sampling flow control and a miniature low-power vacuum pump. can measure atmospheric pressure automatically, and has pressure compensated function. The host sends commands and receives waveform, breath parameters and command responses on two asynchronous serial data lines (TTL or RS232 level).


Transducer Type LH800 Sidestream CO2 sensor

Sample Rate

50 mL/min, ±10mL/min.

Principle of Operation

Non-dispersive infrared (NDIR) single beam optics, dual wavelength, no moving parts

Initialization Time

Ø Capnogram displayed in less than 5 seconds
Ø Reaching full specifications within 10 minutes.

CO2 Measure Range

Ø 0 - 114 mmHg
Ø 0 - 15%
Ø 0 - 15.2kPa

CO2 Resolution

Ø 0.1 mm Hg 0 to 50 mm Hg
Ø 0.25 mm Hg 50 to 114 mm Hg

CO2 Accuracy

Ø 0 - 40 mmHg ±2 mmHg
Ø 40 - 114 mmHg ±5% of reading

Respiratory Rate

Ø Range 2 to 120 Breaths Per Minute (BPM)
Ø Accuracy ±1 breath


No routine user calibration required


Automatic Barometer Pressure 400 - 800 mmHg.
User selectable O2 / N2O compensation.

Voltage Requirements

5.0 VDC ±5%

Power Consumption

Less than 1.5 Watts typical.

Temperature and Humidity Operating

0° to 40°C, 10 to 90% RH, non-condensing


-40° to 70°C, <90% RH, non-condensing


Pin out:
1. VA 5.0V
2. Shield Shield
3. DGND Digital return
4. VSRC Unused
5. TxD Serial data from LH800
6. RxD Serial data from Host
7. AGND Analog return
8. SYNC Unused

Data Interface

Ø RS232, bi-directional, 19200 baud rate, standard N-8-1.
Ø Fully compatible with Respironics LoFlo communication protocol

Data Output

CO2 gas concentration (mm Hg), End-tidal CO2, Inspired CO2, Respiratory Rate, Automatic barometric pressure compensation.