Nasal CO2 sampling line which is invented by National Medical is used in ETCO2 monitoring occasions (non-intubated patients). This nasal sampling line is firstly dedigned in China. It can ensure that exhaled air can be quickly extracted into a monitor to measure, and ensure less loss of the diffusion and integrationthat while the gas going through the sampling tube, thereby make CO2 waveform real and effective . The gas sampling line has aseptic packaging. All the material is medical non-toxic material, which is disposable supply. The shape of the sampling line is similar to the conventional nasal oxygen tube. However, its inside diameter is much smaller than nasal oxygen tube. And its anti-extrusion bending capacity is also much srtonger. Once using an ordinary nasal oxygen tube instead of the nasal gas sampling line to extract CO2 gas, it will significantly reduce the reading value and affect the recognition of respiratory rate. The port of the sampling line is the standard LUER connector (female), which can connect with the water trap that is in conjunction with external Sidestream ETCO2 module.