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Non-invasive continuous core temperature measurement by zero heat flux
L P J Teunissen1, J Klewer, A de Haan
1TNO, Human Performance, PO Box 23, 3769 ZG, Soesterberg, The Netherlands. lennart.teunissen@tno.nl
Physiological Measurement
|March 30, 2011
Summary
The new zero heat flux (ZHF) forehead sensor accurately tracks core body temperature during rest and exercise. This non-invasive device shows promise for reliable patient monitoring in clinical settings.
Area of Science:
- Biomedical Engineering
- Physiological Monitoring
- Medical Device Technology
Background:
- Accurate continuous core body temperature monitoring is crucial for patient care.
- Existing methods often lack non-invasiveness, reliability, or rapid response.
- The zero heat flux (ZHF) method offers a potential solution for these limitations.
Purpose of the Study:
- To evaluate the performance of a novel ZHF forehead device for continuous core temperature measurement.
- To assess its accuracy, reliability, and response time compared to established core temperature methods.
- To determine its suitability for patient monitoring in various physiological states.
Main Methods:
- A new ZHF forehead sensor was tested on seven healthy subjects.
- Subjects underwent a protocol including rest, submaximal exercise, and recovery.
- Forehead ZHF temperature (T(zhf)) was compared against oesophageal (T(es)) and rectal (T(re)) temperatures.
Main Results:
- T(zhf) demonstrated minimal bias and high agreement with T(es) across all conditions (bias ± SD: 0.17 ± 0.19 °C rest, -0.05 ± 0.18 °C exercise, -0.01 ± 0.20 °C recovery).
- The ZHF method exhibited negligible delay in tracking T(es) changes.
- Rectal temperature (T(re)) showed significant delay and deviation during rapid core temperature fluctuations.
Conclusions:
- The studied ZHF forehead sensor accurately tracks oesophageal temperature in stable, hot ambient conditions.
- It offers a reliable, non-invasive alternative for continuous core temperature monitoring.
- The ZHF method shows significant potential for improving patient monitoring in hospital environments.
Related Concept Videos
01:14Temperature Measurement Sites
A thermometer measures body temperature. The common sites for measuring body temperature are the oral cavity, axillary region, temporal artery, and skin surface, such as the forehead, abdomen, and axilla. True core body temperature is assessed in the rectum, tympanic membrane, pulmonary artery, esophagus, and urinary bladder.
Oral: When assessing oral temperature, the thermometer tip should be placed under the tongue in the posterior sublingual pocket. It offers accurate readings and can be...
Oral: When assessing oral temperature, the thermometer tip should be placed under the tongue in the posterior sublingual pocket. It offers accurate readings and can be...
01:13Equipments Used to Measure Body Temperature
Body temperature can be assessed using various devices and measured in Celsius or Fahrenheit.
Glass-bulb Thermometer:
Glass-bulb thermometers are hollow glass tubes with a bulb tip containing liquid such as ethanol or mercury. Historically, glass bulb mercury thermometers were the standard device to measure body temperature. Today, mercury thermometers are prohibited in many countries due to the hazardous effects of mercury and the risk of exposure if the glass bulb breaks. In general,...
Glass-bulb Thermometer:
Glass-bulb thermometers are hollow glass tubes with a bulb tip containing liquid such as ethanol or mercury. Historically, glass bulb mercury thermometers were the standard device to measure body temperature. Today, mercury thermometers are prohibited in many countries due to the hazardous effects of mercury and the risk of exposure if the glass bulb breaks. In general,...
01:27Assessing Body Temperature - Rectal
Rectal temperature measurement is considered the most precise method for assessing core body temperature and typically registers higher than oral temperature. For adults, the rectal thermometer should be inserted 1 to 1.5 inches into the rectum to obtain the most accurate reading.
Follow these steps for rectal temperature assessment:
Step 1: Perform hand hygiene and don clean gloves to prevent cross-infection.
Step 2: Position the patient in a side-lying position to better visualize the rectal...
Follow these steps for rectal temperature assessment:
Step 1: Perform hand hygiene and don clean gloves to prevent cross-infection.
Step 2: Position the patient in a side-lying position to better visualize the rectal...
01:19Assessing Body Temperature - Temporal Artery
Here is a stepwise guide to assessing the body temperature at the temporal artery using a temporal artery thermometer
Step 1: Perform hand hygiene and don a fresh pair of gloves to prevent cross-infection and ensure patient safety.
Step 2: Explain the procedure to the patient to establish trust. Clear communication establishes trust with the patient, ensures they understand what to expect, promotes cooperation, and enhances comfort during the procedure.
Step 3: Assess the patient's forehead...
Step 1: Perform hand hygiene and don a fresh pair of gloves to prevent cross-infection and ensure patient safety.
Step 2: Explain the procedure to the patient to establish trust. Clear communication establishes trust with the patient, ensures they understand what to expect, promotes cooperation, and enhances comfort during the procedure.
Step 3: Assess the patient's forehead...
01:14Assessing Body Temperature - Axilla
Procedural Guide for Assessing Axillary Body Temperature using a Digital Thermometer:
Step 1: Perform hand hygiene and put on clean gloves to maintain infection control and prevent cross-contamination.
Step 2: Prepare the patient by explaining the procedure to ensure understanding and cooperation. Ensure privacy, expose the axilla, and inform the patient that minimal movement is crucial for an accurate reading.
Step 3: Adjust the patient’s clothing to expose only the axilla. It minimizes...
Step 1: Perform hand hygiene and put on clean gloves to maintain infection control and prevent cross-contamination.
Step 2: Prepare the patient by explaining the procedure to ensure understanding and cooperation. Ensure privacy, expose the axilla, and inform the patient that minimal movement is crucial for an accurate reading.
Step 3: Adjust the patient’s clothing to expose only the axilla. It minimizes...
01:14Assessing Body Temperature - Tympanic membrane
Assessing tympanic membrane temperature involves using a tympanic membrane thermometer (TMT). Here is a step-by-step guide:
Step 1: Begin by practicing good hand hygiene to prevent the transmission of microorganisms.
Step 2: Turn on the thermometer and wait until the ready sign appears on the screen to ensure accurate measurement.
Step 3: Slide the probe cover in place to prevent cross-contamination.
Step 4: Instruct the patient to tilt their head to the side for comfort and check for cerumen...
Step 1: Begin by practicing good hand hygiene to prevent the transmission of microorganisms.
Step 2: Turn on the thermometer and wait until the ready sign appears on the screen to ensure accurate measurement.
Step 3: Slide the probe cover in place to prevent cross-contamination.
Step 4: Instruct the patient to tilt their head to the side for comfort and check for cerumen...