Accuracy of Transcutaneous Carbon Dioxide Tension Measurements during Cardiopulmonary Exercise Testing

Abstract

Background: Measurements of transcutaneous carbon dioxide tension (PtcCO₂) with current devices are proven to provide clinically acceptable agreement with measurements of partial arterial carbon dioxide tension (PaCO₂) in several settings but not during cardiopulmonary exercise testing (CPET). Objectives: The primary objective of this study was to investigate the agreement between PaCO₂ and PtcCO₂ measurements (using a Tosca 500 with a Tosca sensor 92) during CPET. A secondary objective was to investigate the agreement between arterial and transcutaneous oxygen saturation (SaO₂, SpO₂) as measured with this sensor during CPET. Methods: In patients with various pulmonary diseases, PtcCO₂ and SpO₂ were continuously measured and compared with arterial blood gas samples during CPET. A maximum bias of 0.5 kPa and 95% limits of agreement (LOA) of 1 kPa between carbon dioxide pressure (PCO₂) measurements were determined as clinically acceptable. Results: In total 101 ‘paired’ arterial and transcutaneous measurements were obtained from 21 patients. Bias between PaCO₂ and PtcCO₂ was –0.03 kPa with LOA from –0.78 to 0.71 kPa. Bias between SaO₂ and SpO₂ was –1.0% with LOA from –2.83 to 0.83%. Conclusions: Transcutaneous estimations of PCO₂ and SpO₂ are accurate and can be used in CPET, circumvening the need for arterial cannulation.