Performance Test and Calibration in End Tidal Carbon Dioxide Measurements

End-tidal CO2 (EtCO2) is the partial pressure of carbon dioxide in the breath at the end of expiration. The measurement of the partial pressure of carbon dioxide from the airway during respiration is called capnography, and the device that makes the measurement is called capnometry. During measurement, the capnometry is placed between the tracheal tube and the balloon or mechanical ventilator in the intubated patient. Capnography is vital in the evaluation of respiration, ventilation and circulation. Normal EtCO2 value in expiration is (30–45) mmHg. Values between (25–30) mmHg indicate hyperventilation, and EtCO2 above 45 mmHg indicates hypo-ventilation. It is important that these measurement values, which determine the way of intervention to the patient, are measured correctly. This vitally important device, like all other medical devices, should be checked for correct measurement and should be subjected to measurements within the scope of medical metrology. Although there are separate standards and procedures for each medical device to be used in test, control and calibration activities of medical devices, there is still no standardized measurement method for capnometries. In this paper, an improved method is proposed to test the accuracy of End-tidal CO2 measurements in capnometries. Testing and control of a capnometry were also carried out using the mentioned method. The applicability of the measurement method has passed the accreditation audit of the Turkish Accreditation Agency (TÜRKAK) and is within the scope of accreditation according to the TS EN ISO/IEC 17025:2017 standard.