ETCO2 is the sixth basic vital sign besides respiration, body temperature, blood pressure, pulse and arterial oxygen saturation. Carbon dioxide (CO2) curve is used to judge the changes of pulmonary ventilation and blood flow. It is widely used in the fields of clinical anesthesia, cardiopulmonary cerebral resuscitation, post anesthesia recovery room (PACU), ICU, pre hospital emergency, etc.
According to the different gas sampling methods , the ETCO2 gas module have two types: Sidestream ETCO2 gas module and Mainstream ETCO2 gas module.
Gas sampling of the Sidestream ETCO2 gas module is by the air pump with flow regulation. The air flow speed is 20-300ml / min. Compared with the mainstream CO2 module, sidestream mode does not need a closed breathing circuit, and can be used to monitor the CO2 concentration of patients during autonomous respiration in the respiratory monitoring of patients with analgesia or sedation. In addition, the required amount of gas is small, the sensitivity of measurement is high and the reaction is fast (85 MS).
The mainstream ETCO2 gas module connect the infrared detector directly to the tracheal tube connector. The breathing gas can be contacted with the infrared detector directly. Therefore, the mainstream type can only be used for patients with endotracheal intubation, not for monitoring patients with spontaneous respiration.
Compared with Sidestream ETCO2 gas module, mainstream ETCO2 gas module integrates the optical measurement and analysis system and all circuits into the module. It can be worked without air pump, flow control sensor, offset calibration valve, dehydrator and other devices,thus the stability and service life are improved. In addition, the mainstream ETCO2 gas module is directly placed in the patient's airway and has rapid response and higher accuracy. Moreover, the mainstream ETCO2 gas is completely sealed so as to prevent the probe contamination by the patient's secretion.