English 
中文
What is ETCO2 used for? In advanced airway management, ETCO2 is commonly applied by placing a filter between the artificial airway and the sensor to prevent contamination from airway secretions and minimize occupational exposure for healthcare providers. Additionally, the ETCO2 sensor can also be connected to a face mask to provide more information, and the installation process is the same as for an artificial airway, except that the filter is placed between the mask and the sensor.
Prior to 1999, the probability of endotracheal tube misplacement in the esophagus was very high, which was clearly a nightmare for both doctors and patients. When ETCO2 monitoring was introduced and mandated in operating rooms in 1999, the problem was solved. In a 2005 pre-hospital study comparing the incidence of tracheal intubation errors, the probability in the ETCO2 monitoring group was reduced to 0, whereas it was 23% in the non-ETCO2 group. It is worth noting that in patients who have ingested CO2-containing drinks before intubation, ETCO2 values and waveforms can also appear when the endotracheal tube is wrongly placed in the esophagus, but the waveforms are markedly different from normal ones.
What is ETCO2 used for? In patients with cardiac arrest, ETCO2 monitoring can predict patient outcomes. Several studies have shown that patients are unlikely to survive when ETCO2 is less than 10 mmHg. ETCO2 has a significant correlation with the return of spontaneous circulation (ROSC). A study in 1995 found that the average ETCO2 value for surviving patients was 31 mmHg, while that for non-survivors was 4 mmHg.
What is ETCO2 used for? ETCO2 can also provide early indication of ROSC without interrupting chest compressions to check for a pulse. When the patient's circulation returns spontaneously, a large amount of CO2 diffuses into the alveoli, causing an obvious and marked increase in ETCO2 readings, far above the normal range. If ETCO2 remains constant or only slightly increases and remains below the normal range, the likelihood of ROSC is very low. In patients with bronchospasm, the ETCO2 waveform can indicate bronchospasm, as delayed pulmonary emptying causes slow and plateaued increases. In patients with severe asthma, the ETCO2 value is an important predictor of outcome, often being very high (above 50 mmHg) or very low. The level of ETCO2 is strongly associated with the mortality rate of sepsis, with lower ETCO2 levels indicating higher mortality rates. In a study in Orlando, the average ETCO2 reading for surviving patients with sepsis was 32.6 mmHg, while that for deceased patients was 26.5 mmHg.
