Comparison of combined oximetry and cutaneous capnography using a digital sensor with arterial blood gas analysis

Abstract

Background: Cutaneous carbon dioxide tension (PcCO₂) is a promising non-invasive surrogate measure of arterial partial pressure of carbon dioxide (PaCO₂). Objectives: To compare values of PcCO₂ and oxygen saturation (SpO₂) with arterial blood gas (ABG) analysis. Methods: SpO₂ and PcCO₂ were measured with a v-Sign™-sensor (Sentec AG, Therwil, Switzerland) and the values compared with simultaneously obtained SaO₂ and PaCO₂ obtained from ABG analysis (ABL 725, Radiometer, Copenhagen, Denmark) in 275 adult patients referred to the lung function laboratory. Results: Median of the PcCO₂ was 4.7 kPa (interquartile range [IQR] 0.9 kPa). Median of the SpO₂ was 97% (IQR 3%). Bland-Altman analysis for comparison of PcCO₂ with PaCO₂ showed a bias of −0.1 kPa with a precision of ± 0.9 kPa with 3.7% outlying values. Bland-Altman analysis for the comparison of SpO₂ and SaO₂ showed a bias of 20.1 % with a precision of ± 3.5%. There were no complications. Conclusion: There is a good agreement between combined cutaneous capnography and oximetry values with ABG analysis. Due to the excellent safety profile and the short time to get a continuous measurement, this technique should be examined in settings where it can complement repeated ABG analysis when ventilatory disturbances are suspected or non-invasive monitoring of ventilation is needed.

Key Words::

• Arterial blood gas analysis
• capnography
• cutaneous carbon dioxide tension
• monitoring
• oxygen saturation

Declaration of interest: Prashant N. Chhajed is on the medical advisory board of Sentec AG.