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Troubleshooting ETCO2 Module C200 C300 by CO2 Wave Forms

Troubleshooting ETCO2 Module C200 C300 by CO2 Wave Forms

There are four kinds of waveform that you will see in your patient monitor screen: normal waveform, ďFly in the SkyĒ type-waveform too high, waveform too small, and SINE Type wave.

1.        Normal waveform


Description of the waveform:

1) Before the ETCO2 module takes any breath, there is a scanning line, which has to be in 0 value. If not, there is something wrong with the ETCO2 module or it has to be calibrated.

2) Once the ETCO2 module C300 or C200 starts to work by taking the breaths, the CO2 real time values form a ladder type wave form with a platform on the top. it rises to 32-34mmHg very quickly and gradually rises to 35-40mmHg to form the platform. After reaching the ETCO2 (the highest value of CO2), it drops to zero sharply, after staying in zero for some time, it starts to form another ladder type platform, then drops to zero again.

3) Between two breaths, there is a zero line, which should be stay in zero value. If it's not zero, something is wrong with the module or Anesthesia machine. In some extreme occasions such as high respire rate, it won't be zero because another breath comes quickly after the previous one, the gas can't be pumped out completely.

4) For the ladder type platform, it starts with a low value point and ends with a high value point, the low value is usually about 32-34mmHg for adult, and the high value, which is the ETCO2 value, is usually $35-40mmHg. While 35-40mmHg within the normal range for regular people, but some patients can go to 80, for example, retention of gas in the lung for a long time; some patients will be relatively low in ETCO2 value due to asthma or shallow respiration, particularly, in high respiration rate, ETCO2 may be only 15, because when the air is inhaled into the lungs, the O2 comes out without being able to exchange into CO2.

2.        waveform too high (fly in the sky type)

Reason: The CO2 recycle device dosenít work normally.

If the ETCO2 module C200 or C300 works during the operation of a tubed patient, this waveform may appear due to the abnormal work of the CO2 recycle device. Mixed gas of O2 and N2 enters into the patientís body, and it becomes gas with CO2 after metabolism. This gas would enter into the anaesthesia machine through the tubes. Usually, CO2 would be consumed by the recycle device in the anaesthesia machine to avoid the take-in of CO2. Once this recycle device doesnít work, the trough of wave would go higher and higher.

Action: Replace the CO2 recycle device with a new one.

3.        Waveform too low

Reason: The ZERO (resetting) hole of the module is jammed.

The ETCO2 module C200 or C300 has auto zero function. When the Zero is carried on, the ETCO2 module would record the gas at the ZERO hole as the zero position. If the hole is jammed or the hole is surround by CO2, a wrong zero position would be recorded, so that the displayed wave of CO2 would be very low.                           

Action: Check whether the ZERO hole is jammed or blocked. If so, clear it and donít have it surrounded by CO2 with high density.

4.        SINE Type waveform 

Reason: The sampling line is too thick in diameter (Recommend to use the sampling line provided by Goldwei).

The diameter our sampling line is smaller than other sampling lines. If the customer uses a sampling line with a larger diameter, the breaths the line carries are more. To elaborate, the place gas of one breath (in and out) takes in a sample line with a small diameter is longer than that with a larger one. If there is gas of more breaths, the gas we breathe in and breathe out would be more easily mixed up in a sampling line with larger diameter. Under this circumstance, the CO2 value would actually become not true. And the waveform displayed would be a sine wave.

Action: Replace the sampling line with the one Goldwei provides.


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