Can mainstream end-tidal carbon dioxide measurement accurately predict the arterial carbon dioxide level of patients with acute dyspnea in ED

• Published in: The American journal of emergency medicine 2012-02, Vol.30 (2), p.358-361
• Main Authors: Cinar, Orhan, MD, Acar, Yahya Ayhan, MD, Arziman, İbrahim, MD, Kilic, Erden, MD, Eyi, Yusuf Emrah, MD, Ocal, Ramazan, MD
• Format: Article
• Language: English
• Subjects: Acute Disease; Agreements; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood; Capnography - methods; Carbon dioxide; Carbon Dioxide - blood; Dyspnea - blood; Dyspnea - physiopathology; Emergency; Emergency and intensive respiratory care; Emergency medical care; Emergency Service, Hospital; Female; Humans; Intensive care medicine; Male; Medical sciences; Methods; Middle Aged; Observational studies; Predictive Value of Tests; Prospective Studies; Studies; Tidal Volume
• ISSN: 0735-6757; 1532-8171
• DOI: 10.1016/j.ajem.2010.12.014

Abstract Objective This study was designed to determine whether the mainstream end-tidal carbon dioxide (ETCO2 ) measurement can accurately predict the partial arterial carbon dioxide (Pa co2 ) level of patients presented to emergency department (ED) with acute dyspnea. Methods This prospective, observational study was conducted at a university hospital ED, which serves more than 110 000 patients annually. Nonintubated adult patients presented with acute dyspnea who required arterial blood gas analysis were recruited in the study for a 6-month period between January and July 2010. Patients were asked to breathe through an airway adapter attached to the mainstream capnometer. Arterial blood gas samples were obtained simultaneously. Results We included 162 patients during the study period. The mean ETCO2 level was 39.47 ± 10.84 mm Hg (minimum, 19 mm Hg; maximum, 82 mm Hg), and mean Pa co2 level was 38.95 ± 12.27 mm Hg (minimum, 16 mm Hg; maximum, 94 mm Hg). There was a positive, strong, statistically significant correlation between ETCO2 and Pa co2 ( r = 0.911, P < .001). The Bland-Altman plot shows the mean bias ± SD between ETCO2 and Pa co2 as 0.5 ± 5 mm Hg (95% confidence interval, −1.3165-0.2680) and the limits of agreement as −10.5 and +9.5 mm Hg. Eighty percent (n = 129) of the ETCO2 measurements were between the range of ±5 mm Hg. Conclusion Mainstream ETCO2 measurement accurately predicts the arterial Pa co2 of patients presented to ED with acute dyspnea. Further studies comparing mainstream and sidestream methods in these patients are required.