The validity of tympanic and exhaled breath temperatures for core temperature measurement

To the Editor.— I would like to comment on the article by Freed and Fraley in the March 1992 issue of Pediatrics.1 I have no argument with their study design and in fact applaud them for using Altman and Bland's method of analysis. Their conclusions, as written, are correct, that the tympanic thermometer "is unreliable compared with conventional methods of temperature determination." The three issues that I would like to raise are: (1) the relative accuracy of rectal and tympanic temperatures in predicting core temperature, (2) rectal temperature as the "gold standard," and (3) axillary thermometry as an acceptable conventional method of clinical temperature.

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A comparison of five methods of temperature measurement in febrile intensive care patients

American Journal of Critical Care ◽

10.4037/ajcc1995.4.4.286 ◽

1995 ◽

Vol 4 (4) ◽

pp. 286-292 ◽

Cited By ~ 76

Author(s):

T Schmitz ◽

N Bair ◽

M Falk ◽

C Levine

Keyword(s):

Intensive Care ◽

Pulmonary Artery ◽

Temperature Measurement ◽

Core Temperature ◽

Rectal Temperature ◽

False Negative ◽

Negative Likelihood Ratio ◽

Likelihood Ratios ◽

Axillary Temperature ◽

Intensive Care Patients

BACKGROUND: A clinically useful temperature measurement method should correlate well with the body's core temperature. Although previous investigators have studied temperature readings from different sites in hypothermic and normothermic patients, none have compared methods specifically in febrile patients. OBJECTIVE: To compare temperature measurement methods in febrile intensive care patients. METHODS: Temperature readings were obtained in rapid sequence from an electronic thermometer for oral and axillary temperature, rectal probe, infrared ear thermometer on "core" setting, and pulmonary artery catheter, approximately every hour during the day and every 4 hours at night. The sample consisted of 13 patients with pulmonary artery catheters and with temperatures of at least 37.8 degrees C. RESULTS: Rectal temperature correlated most closely with pulmonary artery temperature. Rectal temperature showed closest agreement with pulmonary artery temperature, followed by oral, ear-based, and axillary temperatures. Rectal and ear-based temperatures were most sensitive in detecting temperatures greater than 38.3 degrees C. Likelihood ratios for detecting hyperthermia were 5.32 for oral, 2.46 for rectal, and 1.97 for ear-based temperature. Rectal and ear-based temperatures had the lowest negative likelihood ratios, indicating the least chance of a false negative reading. Axillary temperature had a negative likelihood ratio of 0.86. CONCLUSIONS: Rectal temperature measurement correlates most closely with core temperature. If the rectal site is contraindicated, oral or ear-based temperatures are acceptable. Axillary temperature does not correlate well with pulmonary artery temperature. These results underscore the importance of consistency in method when establishing temperature trends, and of awareness of method when interpreting clinical data.

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Feasibility, Accuracy and Optimal Location for Oesophageal Core Temperature Measurements Using the ProSeal Laryngeal Mask Airway Drain Tube

Anaesthesia and Intensive Care ◽

10.1177/0310057x0303100307 ◽

2003 ◽

Vol 31 (3) ◽

pp. 282-285 ◽

Cited By ~ 6

Author(s):

S. Mitchell ◽

J. Brimacombe ◽

C. Keller

Keyword(s):

Laryngeal Mask Airway ◽

Temperature Measurement ◽

Core Temperature ◽

Optimal Location ◽

Proseal Laryngeal Mask Airway ◽

Laryngeal Mask ◽

Temperature Measurements ◽

Drain Tube ◽

Oesophageal Temperature ◽

Temperature Probe

We determined the feasibility, accuracy and optimal location of oesophageal core temperature measurements using the ProSeal laryngeal mask airway drain tube. Thirty normothermic anaesthetized ventilated adults (ASA 1 to 2, aged 18 to 80 years) were studied. Temperatures were recorded using a thermistor at six different locations (middle of drain tube and at 0 to 20 cm distal to the drain tube in 5 cm increments) and compared to nasopharyngeal (thermistor) and aural (infrared tympanic thermometer) reference core temperatures. The temperature probe was successfully inserted into the oesophagus in all patients at the first attempt. Oesophageal temperature increased with depth from 0 to 5 cm (35.2 v 35.9, P<0.0001) and 5 to 10 cm (35.9 v 36.3, P<0.01), but was unchanged from 10 to 15 cm (36.3 v 36.6) and 15 to 20 cm (36.6 v 36.7). Aural temperature was higher than nasopharyngeal temperature (36.8 v 36.0, P<0.0001). Aural temperature was 0.89 to 1.59°C higher than the oesophagus at 0 to 5 cm and 0.21 to 0.30°C higher than the oesophagus at 15 to 20 cm. Nasopharyngeal temperature was 0.06 to 0.76°C higher than the oesophagus at 0 to 5 cm and 0.62 to 0.84°C lower than the oesophagus at 15 to 20 cm. The lowest temperature was in the mid-point of the drain tube (34.7). We conclude that oesophageal core temperature measurement is feasible and accurate using the ProSeal laryngeal mask airway. The optimal location for the temperature probe is at 15 to 20 cm.

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Precision Core Temperature Measurement of Metals Using an Ultrasonic Phase-Shift Method

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp3030080 ◽

2019 ◽

Vol 3 (3) ◽

pp. 80 ◽

Cited By ~ 1

Author(s):

Olaide F. Olabode ◽

Simon Fletcher ◽

Andrew P. Longstaff ◽

Naeem S. Mian

Keyword(s):

Phase Shift ◽

Temperature Measurement ◽

Core Temperature ◽

Speed Of Sound ◽

Cost Effective ◽

Steel Sample ◽

Manufacturing Processes ◽

Sample Type ◽

Shift Method ◽

Phase Shift Method

Temperature measurement is one of the most important aspects of manufacturing. There have been many temperature measuring techniques applied for obtaining workpiece temperature in different types of manufacturing processes. The main limitations of conventional sensors have been the inability to indicate the core temperature of workpieces and the low accuracy that may result due to the harsh nature of some manufacturing environments. The speed of sound is dependent on the temperature of the material through which it passes. This relationship can be used to obtain the temperature of the material provided that the speed of sound can be reliably obtained. This paper investigates the feasibility of creating a cost-effective solution suitable for precision applications that require the ability to resolve a better than 0.5 °C change in temperature with ±1 °C accuracy. To achieve these, simulations were performed in MATLAB using the k-wave toolbox to determine the most effective method. Based upon the simulation results, experiments were conducted using ultrasonic phase-shift method on a steel sample (type EN24T). The results show that the method gives reliable and repeatable readings. Based on the results from this paper, the same setup will be used in future work in the machining environment to determine the effect of the harsh environment on the phase-shift ultrasonic thermometry, in order to create a novel technique for in-process temperature measurement in subtractive manufacturing processes.

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