Abstract

MORONTA MARTIN, M.ªD.  and  GUTIERREZ ORTEGA, C.. Correlation between pCO₂ values obtained by arterial gasometry and transcutaneous capnography. Sanid. Mil. [online]. 2013, vol.69, n.2, pp.82-86. ISSN 1887-8571.  https://dx.doi.org/10.4321/S1887-85712013000200004.

Introduction: arterial gasometry is the most common and accurate method to determine, among others, the values of arterial blood carbon dioxide (pCO₂). It is an invasive and painful technique rejected by many chronic respiratory disease patients who are followed periodically in outpatient clinics. Objective: To assess whether pCO₂ values obtained by a non-invasive and well tolerated test, as transcutaneous capnography, are valid and can reduce blood gas tests in this group of patients. Patients and Method: In 359 patients from the Pneumology outpatient department, the value of pCO₂ was determined by both techniques, arterial gasometry and transcutaneous capnography. To assess the reliability of the transcutaneous capnography versus the arterial gasometry, the intraclass correlation index was used for individual measures for a random effects factor and its accuracy determined with a confidence interval of 95%. For its graphical representation the Bland-Altman plot was used. The p-value <0.05 was used for statistical significance and the statistical software was SPSS version 15. Results: The intraclass correlation of the pCO₂ values for both techniques was 0.603 (95% CI: 0.533 to 0.665) that can be considered moderate (p<0.001). The average difference was 1.08% in favor of the pCO₂ values obtained by transcutaneous capnography. Conclusions: pCO₂ values obtained by transcutaneous capnography are valid and might be a suitable indicator to determine when to perform arterial gasometries and so reduce or eliminate the unnecessary ones. It is necessary to follow a rigorous protocol to obtain more reliable pCO₂ values by transcutaneous capnography. Transcutaneous capnography minimizes collateral damage versus arterial gasometry.

Keywords : Carbon dioxide partial pressure; Transcutaneous measurement; Arterial blood gas measurement; Invasive; Noninvasive; Capnography.

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