PT  - JOURNAL ARTICLE
AU  - Pekdemir, Murat
AU  - Cinar, Orhan
AU  - Yilmaz, Serkan
AU  - Yaka, Elif
AU  - Yuksel, Melih
TI  - Disparity Between Mainstream And Sidestream End Tidal Carbon Dioxide Values And Arterial Carbon Dioxide Levels
AID  - 10.4187/respcare.02227
DP  - 2013 Jan 15
TA  - Respiratory Care
PG  - respcare.02227
4099  - http://rc.rcjournal.com/content/early/2013/01/15/respcare.02227.short
4100  - http://rc.rcjournal.com/content/early/2013/01/15/respcare.02227.full
AB  - Background: Measuring and monitoring end-tidal carbon dioxide (ETCO2) is an important aspect of care of critical patient. The two methods used for ETCO2 measurement were mainstream and sidestream methods. The aim of the study was assessment of agreement between ETCO2 measurements performed by mainstream and sidestream methods with the partial arterial carbon dioxide pressure (PaCO2) values. Methods: This was a prospective observational study. Total of 114 patients were enrolled in the study. ETCO2 measurements using mainstream and sidestream methods were performed simultaneously with the arterial blood sampling in patients who were observed in the emergency department (ED) and required arterial blood gas (ABG) analysis. Agreement between the ETCO2 measurements and the PaCO2 values obtained from ABG analysis were evaluated using Bland-Altman method. Results: Sixty (52.6%) of them were females and the mean age was 60.9 years (95% CI, 58.3-63.6). The mean PaCO2 level was 35.16 (95% CI, 33.81-36.51), mainstream ETCO2 was 22.11 (95% CI, 21.05-23.18), and sidestream ETCO2 was 25.48 (95% CI, 24.22-26.75). Bland-Altman analysis showed an average difference between mainstream ETCO2 and PaCO2 values as 13 (95% limits of agreement -0.6 – 25.5) and moderate correlation (r=0.548, p<0.001) and an average difference between sidestream ETCO2 and PaCO2 values as 9.7 (95% limits of agreement -5.4 – 24.7) and poor correlation (r=0.407, p<0.001). Conclusion: ETCO2 values obtained from measurements by mainstream and sidestream methods were found to be significantly lower compared to the PaCO2 values. There is essentially no agreement between the measurements obtained by two different methods and the PaCO2 values.