Investigating the Relationship Between End Tidal Carbon Dioxide and Arterial Carbon Dioxide Pressure in Patients With Respiratory Distress Referred to the Emergency Room of Hazrat Rasool Akram Hospital

Background: Measuring End-Tidal Carbon Dioxide (ETCO-2) can be a non-invasive, fast, and reliable method to predict partial pressure of carbon dioxide (PaCO2) in patients with respiratory distress. This method, which can be a suitable substitute to measure PaCO2, is being used in many emergency rooms and operating rooms in developed countries, but its exact relationship with PaCO2 has not been confirmed yet. This study aims to investigate the relationship between PaCO2 and ETCO2 in patients with respiratory distress referred to the emergency. Materials and Methods: Arterial blood gases were measured in patients referred to the emergency room of Hazrat Rasool Akram (PBUH) Hospital with the main complaint of respiratory distress, and the ETCO2 of the patient was measured simultaneously with a capnograph. At the same time, the blood pressure and body temperature of the patients were also measured. The obtained information was collected in a sheet and statistically analyzed using SPSS software version 15. Results: A total of 120 patients were included in the study whose mean age was 48.3. The mean PaCO2 and ETCO2 were 47.45 and 26.9, respectively. The mean respiratory rate was 37.4 and diastolic (89.9) and systolic (124.9) blood pressure. A total of 48.33% of patients were women. Statistical analysis showed a significant relationship between PaCO2 and ETCO2 (P=0.0001; CC=0.436). Linear regression analysis showed that ETCO2 predicts PaCO2 with R=0.424. Conclusion: A good correlation was found between PaCO2 and ETCO2 and this correlation was higher in diseases such as sepsis and COPD. Variables such as age, sex, and blood pressure did not affect this correlation. Of course, more studies on healthy people are necessary to confirm these findings.