Validity of heart rate derived core temperature estimation during simulated firefighting tasks.

Area of Science:

• Physiology
• Occupational Health
• Biomedical Engineering

Background:

• Rectal core temperature monitoring is invasive and impractical for firefighters.
• Non-invasive methods are needed to assess heat injury risk in demanding occupations.
• The EQ02+LifeMonitor aims to provide a practical alternative for core temperature estimation.

Purpose of the Study:

• To validate the EQ02+LifeMonitor against the gold standard rectal thermometer for core temperature assessment.
• To investigate the influence of firefighting turnout gear on core temperature estimation and physiological strain.

Main Methods:

• Thirteen participants performed simulated firefighting tasks in a controlled environmental chamber (40.6°C, 50% humidity).
• Tasks included treadmill walking and deadlifts, performed with and without turnout gear.
• Core temperature was measured simultaneously using the EQ02+LifeMonitor and a DataTherm II rectal thermometer.

Main Results:

• The EQ02+LifeMonitor showed statistically equivalent results to the rectal thermometer, with a minimal difference of ~0.1°C.
• Turnout gear significantly increased heart rate, perceived exertion, and cumulative core temperature, but not skin temperature or ventilatory rate.
• The validity of the EQ02+LifeMonitor's estimated core temperature was not impacted by the use of turnout gear.

Conclusions:

• The EQ02+LifeMonitor is a viable, non-invasive alternative to rectal thermometry for assessing core temperature in firefighters.
• Turnout gear increases physiological strain, but the EQ02+LifeMonitor remains accurate under these conditions.
• The device's heart-rate derived estimation likely accounts for physiological changes, maintaining validity.