title: Clinical validation of a digital transcutaneous PCO2/SpO2 ear sensor in adult patients after cardiac surgery.
abstract: OBJECTIVE
  The aim of this study was to validate the V-Sign digital sensor (SenTec AG, Therweil, Switzerland) for combined noninvasive assessment of pulse oxymetric oxygen saturation (SpO(2)) and transcutaneous carbon dioxide tension (PtcCO(2)) in adults after cardiac surgery.
  
  
  METHODS
  In twenty one patients, aged 51-86 years, simultaneous measurements of blood gases with the V-Sign Sensor and with two Nellcor Durasensors (model DS-100A), one at the opposite earlobe and one with a finger clip, were compared first during hyper-, normo- and hypocapnia and at different pulse rates using a pacemaker, and then at 2-h intervals up to 8 h. Agreement was assessed by Bland-Altman analysis.
  
  
  RESULTS
  PtcCO(2) data of three patients were excluded because of calibration failure of the device. Median (range) PtcCO(2) for the remaining patients was 5.49 (3.3-7.6) kPa and arterial carbon dioxide tension (PaCO(2)) was 5.43 (3.61-7.41) kPa. Corresponding mean bias was +0.05 kPa and limits of agreement (LOA) were -1.2/+1.3 kPa. During normo- and hypoventilation, mean bias was good at +0.02 and +0.04 kPa respectively, but limits of agreement were poor at -0.67/+0.69 and -0.81/+0.88 kPa. In 10 patients, an initial overshoot of PtcCO(2 )was observed. Mean bias of SpO(2) and pulse rate was close to zero (-1.5% and +0.001 bpm respectively), but limits of agreement were unacceptably high (-21.4/+18.4% and -22.3/+22.3 bpm).
  
  
  CONCLUSIONS
  In the present state of development the SenTeC Digital monitor V-Sign device has serious limitations. Additional efforts are necessary to eliminate calibration failures and the initial overshoot of PtcCO(2) as well as to improve detection of SpO(2) and pulse rate.
authors: Division of Cardiac Anaesthesia, Institute of Anaesthesiology, University Hospital of Zurich, Raemistrasse 100, Zurich, 8091, Switzerland. werner.baulig@usz.ch
authors: Werner
authors: W
authors: Baulig
authors: Philipp
authors: P
authors: Schütt
authors: Hans R
authors: HR
authors: Roth
authors: Josef
authors: J
authors: Hayoz
authors: Edith R
authors: ER
authors: Schmid
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015982:Bias; D001785:Blood Gas Monitoring, Transcutaneous / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D002245:Carbon Dioxide / Q000097:blood; D006348:Cardiac Surgical Procedures; D004423:Ear / Q000098:blood supply; D005260:Female; D005385:Fingers / Q000098:blood supply; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
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