Journal of Clinical Monitoring and Computing

, Volume 33, Issue 1, pp 165–172 | Cite as

Evaluation of the novel non-invasive zero-heat-flux Tcore™ thermometer in cardiac surgical patients

  • José A. SastreEmail author
  • María J. Pascual
  • Teresa López
Original Research


Tcore™ Sensor is a novel zero-heat-flux thermometer that estimates core temperature from skin over forehead. We tested the hypothesis that this system estimates core temperature to an accuracy within 0.5 °C. 40 cardiac surgical patients were enrolled (960 measurements). Reference core temperatures were measured in nasopharynx, pulmonary artery and the arterial branch of the oxygenator of the cardiopulmonary bypass (CPB) circuit. 95% Bland–Altman limits of agreement for repeated measurement data was used to study the agreement between Tcore™ thermometer and the reference methods. The proportion of all differences that were within 0.5 °C and Lin’s concordance correlation coefficient (LCCC) were estimated as well. The mean overall difference between Tcore™ and nasopharyngeal temperature was − 0.2 ± 0.5 °C (95% limits of agreement of ± 1.09). The proportion of differences within 0.5 °C was 68.80% (95% CI 65.70–71.70%) for nasopharyngeal reference. LCCC was 0.84 (95% CI 0.83–0.86). The mean bias between Tcore™ and the temperature measured in the pulmonary artery was − 0.2 ± 0.5 °C (95% limits of agreement of ± 1.16). 55.30% of measurements were ≤ 0.5 °C (95% CI 51.40–59.20%). LCCC was 0.60 (95% CI 0.56–0.64). The average difference between Tcore™ and the temperature measured at the arterial outlet during the CPB period was − 0.1 ± 0.7 °C (95% limits of agreement of ± 1.43). The proportion of differences within 0.5 °C was 54.40% (95% CI 48.80–60.00%). LCCC was 0.74 (0.69–0.79). Cutaneous forehead zero-flux temperatures were not sufficiently accurate for routine clinical use in the cardiac surgical population.


Anesthesia Body temperature Cardiac surgical procedures Thermometers 


Author contributions

JAS: Study design, patient recruitment, data collection, data analysis, drawing up the first draft of the paper and correspondence ; MJP: Study design, drawing up the first draft of the paper; TL: Study design, drawing up the first draft of the paper. All coauthors approved the final version of the manuscript.


Drägerwerk AG & Co (Germany) provided the Tcore™ thermometer used for the study. None of the authors has a personal financial interest in this research.

Compliance with ethical standards

Conflict of interest

Dr. José A. Sastre has received an honorarium from Smiths Medical for teaching on perioperative temperature management and from 3M for the prize “Temperature monitoring and prevention of hypothermia”, of the Spanish Society of Anesthesiology. Maria J. Pascual and Teresa López have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer Science+Business Media B.V., part of Springer Nature 2018

Authors and Affiliations

  • José A. Sastre
    • 1
    Email author
  • María J. Pascual
    • 1
  • Teresa López
    • 2
  1. 1.Department of AnesthesiologySalamanca University HospitalSalamancaSpain
  2. 2.Department of AnesthesiologyNuestra Señora de Sonsoles HospitalÁvilaSpain

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