Transcutaneous monitoring as a replacement for arterial PCO(2) monitoring during nocturnal non-invasive ventilation

Respir Med. 2011 Jan;105(1):143-50. doi: 10.1016/j.rmed.2010.10.007. Epub 2010 Oct 28.


Background: Continuous, non-invasive assessment of alveolar ventilation achieved by transcutaneous PCO(2) (PtcCO(2)) monitoring is clearly superior to intermittent, invasive blood gas analyses in patients receiving nocturnal non-invasive positive pressure ventilation (NPPV), but the reliability and accuracy of PtcCO(2)-monitoring is still disputed. The present study was aimed at investigating the capability of modern PtcCO(2)-monitoring to reliably assess alveolar ventilation during nocturnal NPPV.

Methods: Capillary blood gas measurements (11pm, 2am, 5am and 7am) and 8 h of continuous PtcCO(2)-monitoring using three of the latest generation devices (SenTec Digital Monitor, Radiometer TCM4-TINA and Radiometer TOSCA500) were performed during polysomnography-proven sleep studies in 24 patients receiving NPPV (15 with COPD, 9 with restrictive disorders).

Results: The technical calibration drift for SenTec DM, TCM4-TINA and TOSCA500 was 0.1, -0.4 and -0.5 mmHg/h, respectively. Bland-Altman method comparison of PaCO(2)/drift-uncorrected PtcCO(2) revealed a mean bias (limits of agreement) of 1.0 (-4.7 to 6.7), -1.5 (-15.6 to 12.5) and 0.8 (-6.8 to 8.3) mmHg, respectively. Continuous overnight PtcCO(2)-monitoring detected variations in alveolar ventilation, with median ranges of 12.3 (10.7-14.5) mmHg for SenTec DM, 14.5 (12.5-17.0) mmHg for TCM4-TINA and 11.5 (11.0-13.0) mmHg for TOSCA500 (RM-ANOVA, p < 0.001). The four capillary PaCO(2) values ranged by a median of 6.3 (4.7-9.7) mmHg.

Conclusions: Modern PtcCO(2)-monitoring is reliable, accurate and robust. Since PtcCO(2)-monitoring is also non-invasive, does not disrupt sleep quality and provides a more complete picture of alveolar ventilation than intermittent capillary PaCO(2), PtcCO(2)-monitoring should become the preferred technique for assessing alveolar ventilation during nocturnal NPPV.

Trial registration: DRKS00000433 at

Publication types

  • Evaluation Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Biomarkers / blood
  • Blood Gas Monitoring, Transcutaneous / methods*
  • Calibration
  • Carbon Dioxide / blood*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Polysomnography
  • Positive-Pressure Respiration / methods*
  • Sleep


  • Biomarkers
  • Carbon Dioxide