Temperature Difference between Brain and Axilla according to Body Temperature in the Patient with Brain Injury

Area of Science:

• Neuroscience
• Medical Thermology
• Critical Care Medicine

Background:

• Accurate brain temperature monitoring is crucial for managing patients with brain injuries.
• Estimating brain temperature using peripheral body measurements like axillary temperature is common but debated.
• Understanding the brain-axilla temperature gradient is essential for clinical decision-making.

Purpose of the Study:

• To investigate the temperature gradient between brain and axilla in relation to body temperature in patients with brain injury.
• To quantify the difference between direct brain temperature measurements and axillary temperature readings.

Main Methods:

• A cohort of 135 patients undergoing cranial surgery with implanted thermal diffusion flow meters (TDF) was analyzed.
• Simultaneous brain and axillary temperatures were recorded every 2 hours using TDF devices and mercury thermometers.
• Data were categorized into hypothermia (<36.4°C), normothermia (36.5°C–37.5°C), and hyperthermia (>37.6°C) based on axillary temperature.

Main Results:

• The overall mean brain-axilla temperature difference was 0.93±0.50°C.
• This gradient was largest during hypothermia (1.28±0.56°C), followed by normothermia (0.87±0.43°C) and hyperthermia (0.71±0.41°C).
• Statistically significant differences in temperature gradients were observed between hypothermia and normothermia groups (p=0.000).

Conclusions:

• Brain temperature is consistently higher than axillary temperature in this patient cohort.
• Hypothermia therapy is associated with substantial brain-axilla temperature gradients.
• Axillary temperature can serve as a practical proxy for estimating brain temperature, particularly when direct measurement is not feasible.