An Evaluation of a Zero-Heat-Flux Cutaneous Thermometer in Cardiac Surgical Patients

BACKGROUND:Although core temperature can be measured invasively, there are currently no widely available, reliable, noninvasive thermometers for its measurement. We thus compared a prototype zero-heat-flux thermometer with simultaneous measurements from a pulmonary artery catheter. Specifically, we tested the hypothesis that zero-heat-flux temperatures are sufficiently accurate for routine clinical use. METHODS:Core temperature was measured from the thermistor of a standard pulmonary artery catheter and with a prototype zero-heat-flux deep-tissue thermometer in 105 patients having nonemergent cardiac surgery. Zero-heat-flux probes were positioned on the lateral forehead and lateral neck. Skin surface temperature probes were attached to the forehead just adjacent to the zero-heat-flux probe. Temperatures were recorded at 1-minute intervals, excluding the period of cardiopulmonary bypass, and for the first 4 postoperative hours. Zero-heat-flux and pulmonary artery temperatures were compared with bias analysis; differences exceeding 0.5°C were considered to be potentially clinically important. RESULTS:The mean duration in the operating room was 279 ± 75 minutes, and the mean cross-clamp time was 118 ± 50 minutes. All subjects were monitored for an additional 4 hours in the intensive care unit. The average overall difference between forehead zero-heat-flux and pulmonary artery temperatures (i.e., forehead minus pulmonary artery) was −0.23°C (95% limits of agreement of ±0.82); 78% of the differences were ⩽0.5°C. The average intraoperative temperature difference was −0.08°C (95% limits of agreement of ±0.88); 84% of the differences were ⩽0.5°C. The average postoperative difference was −0.32°C (95% limits of agreement of ±0.75); 84% of the differences were ⩽0.5°C. Bias and precision values for neck site were similar to the forehead values. Uncorrected forehead skin temperature showed an increasing negative bias as core temperature decreased. CONCLUSIONS:Core temperature can be noninvasively measured using the zero-heat-flux method. Bias was small, but precision was slightly worse than our designated 0.5°C limits compared with measurements from a pulmonary artery catheter.

[1]  D. Sessler,et al.  Thermoregulatory Vasoconstriction Impairs Active Core Cooling , 1995, Anesthesiology.

[2]  M. Yamakage,et al.  Evaluation of a newly developed monitor of deep body temperature , 2002, Journal of Anesthesia.

[3]  D. Sessler,et al.  Postanesthetic Vasoconstriction Slows Peripheral-to-Core Transfer of Cutaneous Heat, Thereby Isolating the Core Thermal Compartment , 1997, Anesthesia and analgesia.

[4]  M. Ozaki,et al.  Temperatures measured by a deep body thermometer (Coretemp) compared with tissue temperatures measured at various depths using needles placed into the sole of the foot. , 1996, European journal of anaesthesiology.

[5]  Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. , 1998, JAMA.

[6]  T. Tsuji,et al.  Patient monitoring during and after open heart surgery by an improved deep body thermometer. , 1987, Medical progress through technology.

[7]  R H Fox,et al.  A new method for monitoring deep body temperature from the skin surface. , 1973, Clinical science.

[8]  D. Lees,et al.  Noninvasive Determination of Core Temperature During Anesthesia , 1980, Southern medical journal.

[9]  Xin Zhu,et al.  Development of a new method for the noninvasive measurement of deep body temperature without a heater. , 2010, Medical engineering & physics.

[10]  D. Brajkovic,et al.  Confounding factors in the use of the zero-heat-flow method for non-invasive muscle temperature measurement , 2005, European Journal of Applied Physiology.

[11]  E. Mascha,et al.  The Effects of Mild Perioperative Hypothermia on Blood Loss and Transfusion Requirement , 2008, Anesthesiology.

[12]  M. Fukuoka,et al.  Twenty-four hour monitoring of deep body temperature with a novel flexible probe. , 1987, Journal of biomedical engineering.

[13]  D. Leaper,et al.  Effects of preoperative warming on the incidence of wound infection after clean surgery: a randomised controlled trial , 2001, The Lancet.

[14]  Makoto Ozaki,et al.  Comparison of distal oesophageal temperature with “deep” and tracheal temperatures , 1997, Canadian journal of anaesthesia = Journal canadien d'anesthesie.

[15]  U. Illievich,et al.  Temporal Artery Versus Bladder Thermometry During Perioperative and Intensive Care Unit Monitoring , 2007, Anesthesia and analgesia.

[16]  D. Sessler,et al.  Accuracy and precision of a novel non-invasive core thermometer. , 2009, British journal of anaesthesia.

[17]  S. Muravchick.  Deep body thermometry during general anesthesia. , 1983, Anesthesiology.

[18]  Solman Aj,et al.  New thermometers for deep tissue temperature. , 1973 .

[19]  P. Mackowiak,et al.  A critical appraisal of 98.6 degrees F, the upper limit of the normal body temperature, and other legacies of Carl Reinhold August Wunderlich. , 1992, JAMA.

[20]  P. Iaizzo,et al.  Thermal Response in Acute Porcine Malignant Hyperthermia , 1996, Anesthesia and analgesia.

[21]  T Togawa,et al.  Body temperature measurement. , 1985, Clinical physics and physiological measurement : an official journal of the Hospital Physicists' Association, Deutsche Gesellschaft fur Medizinische Physik and the European Federation of Organisations for Medical Physics.

[22]  T. Sakuragi,et al.  Deep body temperature during the warming phase of cardiopulmonary bypass. , 1993, British journal of anaesthesia.

[23]  Toshio Kobayashi,et al.  A modified internal temperature measurement device , 1976, Medical and biological engineering.

[24]  S B Wilson,et al.  A tissue heat transfer model for relating dynamic skin temperature changes to physiological parameters. , 1988, Physics in medicine and biology.

[25]  D. Altman,et al.  Agreement Between Methods of Measurement with Multiple Observations Per Individual , 2007, Journal of biopharmaceutical statistics.

[26]  L. Lin,et al.  A concordance correlation coefficient to evaluate reproducibility. , 1989, Biometrics.

[27]  Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. , 1996, The New England journal of medicine.

[28]  John L Moran,et al.  Tympanic temperature measurements: Are they reliable in the critically ill? A clinical study of measures of agreement* , 2007, Critical care medicine.

[29]  R H Fox,et al.  A new technique for monitoring the deep body temperature in man from the intact skin surface. , 1971, The Journal of physiology.

[30]  E. Mascha,et al.  Noninvasive Temperature Monitoring in Postanesthesia Care Units , 2009, Anesthesiology.

[31]  Losowsky Ms,et al.  A clinical apraisal of transcutaneous deep body temperature. , 1973 .

[32]  Fox Rh,et al.  A new technique for monitoring the deep body temperature in man from the intact skin surface. , 1971, The Journal of physiology.

[33]  M. Losowsky,et al.  A clinical apraisal of transcutaneous deep body temperature. , 1973, Biomedicine / [publiee pour l'A.A.I.C.I.G.].

[34]  D. Sessler,et al.  Influence of Thermoregulatory Vasomotion and Ambient Temperature Variation on the Accuracy of Core‐temperature Estimates by Cutaneous Liquid‐crystal Thermometers , 1997, Anesthesiology.

[35]  S. Dollberg,et al.  Continuous measurement of core body temperature in preterm infants. , 2000, American journal of perinatology.

[36]  D. Sessler,et al.  Mild Intraoperative Hypothermia Prolongs Postanesthetic Recovery , 1997, Anesthesiology.

[37]  D. Altman,et al.  Measuring agreement in method comparison studies , 1999, Statistical methods in medical research.

[38]  T. Togawa,et al.  Improved probe for a deep body thermometer , 2006, Medical and Biological Engineering and Computing.

[39]  D. Delpy,et al.  A new combined deep-body-temperature/NIRs probe for noninvasive metabolic measurements on human skeletal muscle. , 1999, Advances in experimental medicine and biology.

[40]  M. Yamakage,et al.  Deep temperature monitoring using a zero-heat-flow method , 2003, Journal of Anesthesia.

[41]  Toshio Kobayashi,et al.  Improvement of deep body thermometer for man , 2006, Annals of Biomedical Engineering.

[42]  M. Ozaki,et al.  “Deep-forehead” temperature correlates well with blood temperature , 2000, Canadian journal of anaesthesia = Journal canadien d'anesthesie.

[43]  D. Sessler,et al.  Insufficiency in a New Temporal-Artery Thermometer for Adult and Pediatric Patients , 2002, Anesthesia and analgesia.

[44]  A. Kurz,et al.  Perioperative normothermia to reduce the incidence of surgical-wound infection and shorten hospitalization. Study of Wound Infection and Temperature Group. , 1996, The New England journal of medicine.

[45]  T. Akata,et al.  Reliability of temperatures measured at standard monitoring sites as an index of brain temperature during deep hypothermic cardiopulmonary bypass conducted for thoracic aortic reconstruction. , 2007, The Journal of thoracic and cardiovascular surgery.

[46]  D. Sessler,et al.  Temperature Monitoring and Perioperative Thermoregulation , 2008, Anesthesiology.

[47]  A. Nakai,et al.  Correlations between interscapular deep temperature and plasma free fatty acid levels in pregnant women with hyperemesis gravidarum , 2003, Archives of Gynecology and Obstetrics.