Minor Decrease of Core Temperature in Shivering Volunteers Over a 3-Hour Exposure to Cold, Wet, and Windy Conditions.

Area of Science:

• Environmental Physiology
• Trauma Medicine
• Thermoregulation

Background:

• Hypothermia significantly increases mortality in trauma patients.
• Accurate hypothermia diagnosis in conscious patients is challenging due to limited equipment.
• Shivering, a thermoregulatory response, is a clinical indicator of hypothermia.

Purpose of the Study:

• To investigate core temperature changes in simulated prehospital hypothermia.
• To assess the thermogenic effect of shivering under cold, wet, and windy conditions.
• To describe core temperature trajectories in shivering individuals.

Main Methods:

• Fifteen healthy volunteers were exposed to a 5.0°C climate chamber with wet clothing for 3 hours.
• Core body temperature was measured using esophageal probes (Teso) and ingestible capsules (Tcap).
• Shivering was quantified via oxygen consumption (VO2) and objective observation.

Main Results:

• Core temperature showed a slight reduction (Teso: 0.25°C, Tcap: 0.11°C) after 3 hours.
• Initial core temperature increased, and the cooling rate was 0.17°C·h⁻¹ (Teso).
• VO2 correlated with observed shivering and inversely with Teso.

Conclusions:

• Healthy individuals maintained normal core temperatures for 3 hours under simulated harsh conditions.
• Shivering's heat production is crucial for maintaining normothermia.
• Absence of shivering in cold environments is a critical warning sign for hypothermia in patients.