Evaluation of the relationship between intraoperative end-tidal carbon dioxide levels and blood pressure measurements

Objective: Intraoperative end-tidal carbon dioxide (EtCO2) monitoring is a non-invasive method that provides information about the respiratory system and metabolism in patients under general anesthesia. In this study, the relationship between EtCO2 level and systolic (SAB), diastolic (DAB), mean (OAP) arterial pressure values and heart rate in the intraoperative period was investigated. Materials and Methods: Eighty-five patients (18-55 years-old) operated under general anesthesia were included. EtCO2 levels, SAB, DAB, OAP, heart rate and oxygen saturation values were recorded at five-minute intervals throughout the operation. Correlation coefficients were calculated to evaluate the relationship between EtCO2-SAB, EtCO2-DAB, EtCO2-OAB and EtCO2-heart rate for each participant. Consistency of the correlation coefficients among the participants was evaluated with one-sample t-test. Results: The mean correlation coefficients were 0.56±0.37 for EtCO2-SAB, 0.47±0.39 for EtCO2-DAB, 0.50±0.38 for EtCO2-OAB, and 0.40±0.49 for EtCO2-heart rate. The consistency of the correlation coefficients among the participants was statistically significant (EtCO2-SAB p<0.00001; EtCO2-DAB p<0.00001, EtCO2-OAB p<0.00001, and EtCO2-heart rate p<0.00001). Conclusions: Our results show that there is a positive correlation between EtCO2 levels and arterial blood pressure measurements and heart rate. This relationship might indicate that EtCO2 monitoring, allows non-invasive continuous measurement, may enable rapid monitoring of acute changes in the patient's arterial blood pressure during the intraoperative period.