@article {Rosierrespcare.02726, author = {S{\'e}bastien Rosier and Yoann Launey and Jean-Paul Bleichner and Bruno Laviolle and Alice Jouve and Yannick Malledant and Philippe Seguin}, title = {The accuracy of transcutaneous PCO2 in severe brain injury patients: a comparison with end-tidal PCO2}, elocation-id = {respcare.02726}, year = {2013}, doi = {10.4187/respcare.02726}, publisher = {Respiratory Care}, abstract = {Background: In patients suffering from brain injury, end-tidal PCO2 (PETCO2) monitoring is controversial but transcutaneous PCO2 (PtcCO2), which is noninvasive and utilizes real-time display, may be an alternative method. We hypothesized that PtcCO2 would be more accurate than PETCO2 for monitoring PaCO2 in severe brain injury patients. Methods: A prospective observational study included consecutive mechanically ventilated adult subjects who had acute brain injury and an arterial catheter in place. When an arterial blood gas analysis was required, the PETCO2 and PtcCO2 values were simultaneously recorded. The agreement between the PETCO2, PtcCO2 and arterial PCO2 (PaCO2) measurements (reference) was determined using the Bland-Altman method. The number of outliers defined by the formula ([PETCO2 or PtcCO2] - PaCO2) \> {\textpm} 4 mmHg indicated the proportion of measurements that were considered clinically unacceptable. Results: A total of 25 subjects were included in the study, and 85 simultaneous measurements of PaCO2, PtcCO2 and PETCO2 were obtained. The bias and precision between PaCO2 and PtcCO2 were -0.75 and 6.23 mmHg, respectively. The limits of agreement ranged from -12.97 to 11.47 mmHg. The bias and precision between PaCO2 and PETCO2 were 0.68 and 5.82 mmHg, respectively. The limits of agreement ranged from -10.72 to 12.08 mmHg. There were 34 (40\%) outliers for the PtcCO2 sensor and 34 (40\%) outliers for the PETCO2 sensor (P = 1). Conclusions: The accuracy of PtcCO2 was not superior to that of PETCO2 for assessing PCO2 levels and should not be used to monitor these levels in severe brain injury subjects.}, issn = {0020-1324}, URL = {https://rc.rcjournal.com/content/early/2013/12/03/respcare.02726}, eprint = {https://rc.rcjournal.com/content/early/2013/12/03/respcare.02726.full.pdf}, journal = {Respiratory Care} }