Background: Patient arriving in emergency room need rapid reliable evaluation of their respiratory status. Main stream End-tidal carbon dioxide is one of the methods used for this purpose in intubated patients. Side stream end-tidal carbon dioxide might be a non invasive, rapid and reliable predictor of arterial pCO2 in non intubated patients in respiratory distress. AIM: The aim of this study was to verify whether the end-tidal carbon dioxide (ETCO2) can accurately predict the arterial partial pressure of carbon dioxide (pCO2). Meterials And Methodes: This study was on patients were 37 females and 61 males who came to emergency room for respiratory distress. End-tidal carbon dioxide level was recorded at the same time of arterial blood gas sampling for all patients. Other parameters recorded were: Age, Pulse, Blood pressure, Respiratory rate, Arterial blood gas abnormalities, Saturation, and Medical diagnosis. In our study we included all patients presented in ER with respiratory distress. Pregnant, pediatric age groups patients were excluded in this study. Results: In this study a significant correlation was found between arterial partial pressure of CO2 and End-tidal CO2 (p Value = <0.001) in patients with respiratory distress, in the Emergency room. Conclusions: In this study conclude that, there is a significant orrelation between arterial partial pressure of CO2 and End-tidal CO2 in patients with respiratory distress, in mergency room. Further studies are needed to confirm these findings
