The revised digital transcutaneous PCO2/SpO2 ear sensor is a reliable noninvasive monitoring tool in patients after cardiac surgery

J Cardiothorac Vasc Anesth. 2011 Apr;25(2):243-9. doi: 10.1053/j.jvca.2010.06.021. Epub 2010 Sep 20.


Objective: The aim of this study was to validate the revised SenTec V-Sign 2 sensor (SenTec AG, Therwil, Switzerland) for combined noninvasive continuous assessment of pulse rate, pulse oximetry (SpO(2)), and transcutaneous carbon dioxide tension (PtcCO(2)) in adults after cardiac surgery.

Design: A prospective clinical study.

Setting: A single-center university hospital.

Participants: Twenty adult patients aged 36 to 84 years after cardiac surgery.

Interventions: SpO(2) and PtcCO(2) values of three V-Sign 2 sensors (SenTec AG) attached at the earlobe, forehead, and cheek and SpO(2) values of the Nellcor Durasensor (Model DS-100A; Nellcor Puritan Bennett Inc, Pleasanton, CA) were compared with simultaneous measurements of blood gases and end-expiratory carbon dioxide.

Measurements and main results: Measurements were performed during periods of hyper-, normo-, and hypocapnia and then at 30-minute intervals up to 5 hours. Bland-Altman analysis and simple regression analysis were used.

Results: The detection failures for PtcCO(2) were 0.3% to 1.3%, for SpO(2) 10% to 25%, and for pulse rate 5% to 10%. The V-Sign 2 earlobe sensor provided the best results. The mean bias and limits of agreement for PtcCO(2ear) and PaCO(2) were 1.1 and -3.4/+5.5 mmHg. The drift of PtcCO(2) was negligible at all locations. The mean bias and limits of agreement of V-Sign SpO(2ear) and SaO(2), as well as V-Sign pulse rate and the electrocardiogram, were -1.7% and -6.8/+3.9% and 1.2 beats/min and -3.3/+5.8 beats/min. End-expiratory carbon dioxide showed a weak correlation with PaCO(2) (r(2) = 0.47).

Conclusions: Transcutaneous capnometry using the revised V-Sign 2 sensor at the earlobe is a reliable monitoring tool during the recovery period of patients after cardiac surgery. This approach has the potential to reduce the number of arterial blood gas samples.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Gas Analysis / methods
  • Blood Gas Analysis / standards
  • Blood Gas Monitoring, Transcutaneous / methods
  • Blood Gas Monitoring, Transcutaneous / standards
  • Cardiac Surgical Procedures* / adverse effects
  • Cardiac Surgical Procedures* / methods
  • Ear / blood supply*
  • Ear / physiology*
  • Female
  • Humans
  • Hypercapnia / blood
  • Hypercapnia / diagnosis
  • Hypocapnia / blood
  • Hypocapnia / diagnosis
  • Male
  • Middle Aged
  • Monitoring, Physiologic / methods
  • Monitoring, Physiologic / standards
  • Oximetry / methods*
  • Oximetry / standards
  • Prospective Studies