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 (ETCO۲) can be a non-invasive, fast, and reliable method to predict partial pressure of carbon dioxide (PaCO۲) in patients with respiratory distress. This method, which can be a suitable substitute to measure PaCO۲, is being used in many emergency rooms and operating rooms in developed countries, but its exact relationship with PaCO۲ has not been confirmed yet. This study aims to investigate the relationship between PaCO۲ and ETCO۲ 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 ETCO۲ 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 ۱۵. Results: A total of ۱۲۰ patients were included in the study whose mean age was ۴۸.۳. The Mean PaCO۲ and ETCO۲ were ۴۷.۴۵ and ۲۶.۹, respectively. The mean respiratory rate was ۳۷.۴ and diastolic (۸۹.۹) and systolic (۱۲۴.۹) blood pressure. A total of ۴۸.۳۳% of patients were women. Statistical analysis showed a significant relationship between PaCO۲ and ETCO۲ (P=۰.۰۰۰۱; CC=۰.۴۳۶). Linear regression analysis showed that ETCO۲ predicts PaCO۲ with R=۰.۴۲۴. Conclusion: A good correlation was found between PaCO۲ and ETCO۲ 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.