Management of Heat and Cold Stress Guidance to NATO Medical Personnel

This report was published by North Atlantic Treaty Organization (NATO) in 2013 (here).

Note: This publication was not submitted to ExultX Spotlight by the authors or the institution. However, due to its relevance, we have decided to share it with our community. This text is a commentary on the original publication, attempting to highlight the key points. For a more thorough and complete understanding of the content, we strongly recommend everyone to read the original publication.

All rights to the findings belong to the authors or institution of the publication. Responsibility for the commentary lies with ExultX.

Heat and cold stress refer to the physical strain experienced by the human body due to extreme temperatures. Heat stress occurs when the body is unable to cool itself efficiently, leading to conditions such as heat exhaustion and heat stroke. This happens due to high environmental temperatures, intense physical activity, inadequate hydration, and insufficient acclimatization. Common injuries associated with heat stress include heat cramps, heat syncope, heat exhaustion, and potentially fatal heat stroke. Conversely, cold stress arises when the body loses heat faster than it can produce it, which can occur in cold weather, windy conditions, and wet environments. This stress can result in injuries such as frostbite, hypothermia, and non-freezing cold injuries like chilblains and trench foot. Both types of stress impair physical and cognitive performance, requiring proactive measures like proper hydration, appropriate clothing, acclimatization, and continuous monitoring to prevent and manage these conditions effectively.

Besides the main aim of the publication, which is to provide evidence-based guidance to North Atlantic Treaty Organization (NATO) medical personnel and leadership on managing heat and cold stress injuries, it also serves as crucial guidance for physiologists, strength and conditioning coaches, and tactical fitness instructors. Although this publication is oriented towards military settings, it contains valuable information for other tactical settings that operate in extreme environments.

The highlights of the publication are:

Heat and Cold Stress Management: The document details mechanisms of body heat exchange in different environments, the physiological responses to these stresses, and the associated risks.

Risk Management Processes: For both heat and cold stress injuries, the publication outlines comprehensive risk management processes. These include identifying environmental, mission, and individual risk factors and taking appropriate measures to mitigate them.

Specific Countermeasures: Practical advice is given for immediate interventions for each injury.

Key Takeaways

Understanding Heat and Cold Stress: The injury risk cannot be assessed properly based only on temperature. It is important to use indexes that better translate the impact of the environment on our bodies. Assessing, analyzing, and understanding the Wet-Bulb Globe Temperature (WBGT) and the Wind-Chill Temperature Index (WCTI) are fundamental to translating this information into practical mitigation actions.

Comprehensive Risk Management: It is fundamental to have a thorough risk management process, continually re-evaluated as conditions change, to prevent heat and cold injuries.

Leadership and Coordination: It is mandatory to emphasize the significance of effectively implementing guidelines, decision-making algorithms, and protocols among the chain of command, instructors, medical staff, operators, and other operational staff. A good understanding of the subject and the implementation of these algorithms and protocols can drastically reduce reaction time.

Educational Initiatives: Ongoing educational initiatives are essential to inform the chain of command, instructors, medical staff, operators, and other operational staff about the risks of thermal stress and the significance of self-monitoring and reporting symptoms early. Regularly conducting simulations is crucial to establish routines and verify the practicability of the processes.

Proactive Measures: The publication highlights the need for proactive measures such as acclimatization, proper hydration, appropriate clothing, and education of personnel to minimize the risk of thermal injuries. We summarize the measures for extreme cold and heat environments as follows:

Prevention Measures

Heat Stress Prevention:

Acclimatization: Gradually increasing exposure to heat to enhance the body's cooling efficiency.

Hydration: Ensuring adequate fluid intake before, during, and after activities.

Clothing: Wear lightweight, breathable clothing to allow heat dissipation. Showers to wet down operators' clothing have been utilized with limited effectiveness and can lead to skin irritation. The combination of opening clothing and fanning the sweat-soaked underlayers can provide some cooling.

Cooling: Immersing the arms is a simple and effective cooling method. By placing the hands and forearms in cool water (10-20ºC or 50-68ºF), core body temperature can be reduced by 0.5-1.0ºC in just 10 minutes.

Monitoring: Use tools like the WBGT to assess risk and adapt activities, clothing, and hydration accordingly.

Cold Stress Prevention:

Layering Clothing: Wear multiple layers to trap heat and protect against wind and moisture.

Dryness: Keep clothes and skin dry to prevent conductive heat loss.

Warmth: Use insulated clothing and proper boots to maintain body temperature.

Limiting Exposure: Reduce time spent in cold environments and take regular breaks to warm up.

Monitoring: Use tools like the WCTI to assess risk and adapt activities and clothing accordingly.

Despite the publication presenting in detail how to manage each cold and heat stress injury, we will solely focus on the management of heat exhaustion, heat stroke, and hypothermia, as outlined below:

Heat exhaustion and heat stroke management:

1. Immediate Cooling: Rapidly cooling the body is fundamental. Remove the person from direct sunlight (if possible), and loosen or remove clothing. Have the person lie flat and elevate their feet. Use ice packs, cool or cold-water immersion, or ice sheets to rapidly decrease body temperature.

2. Hydration: Provide fluids with electrolytes to rehydrate and restore balance. As recovery occurs, offer fluids to drink, initially providing one full canteen (quart or liter) of cool water every 30 minutes.

3. Medical Attention: If heat exhaustion symptoms (e.g., faintness, nausea, confusion) persist for more than 30 minutes, evacuate for further medical care. If severe mental status changes (e.g., delirium or convulsions) occur, heat stroke may be present and the person must be immediately evacuated. Heat stroke is a medical emergency and can lead to death.

4. Rest: Cease physical activity according to medical indications.

Hypothermia management

1. Drying: Remove the person from the cold to a warm area if possible. Remove wet clothing and dry the skin.

2. Gradual Warming: Slowly warm the body using emergency blankets, dry blankets, or a sleeping bag. Provide warm beverages to conscious victims. Avoid rapid heating and manipulating extremities (do not massage or give alcohol).

3. Insulation: Apply additional layers to retain body heat.

4. Rest: Minimize handling or moving the victim to avoid inducing cardiac arrest.

5. Medical Attention: Severe hypothermia is a medical emergency, and victims should be evacuated as soon as possible.

Conclusions

Critical Nature of Thermal Stress Management: Proper management of heat and cold stress is crucial for maintaining the health and operational effectiveness of forces in various climates.

Need for Continuous Education and Training: Continuous education and training of personnel at all levels are necessary to ensure the principles of thermal stress management are well understood and implemented.

Evidence-Based Practices: The adoption of evidence-based practices is essential for effective thermal stress management, which includes using specific tools like the WBGT and WCTI for real-time assessment and decision-making.

Real Life Day-to-Day Application

Risk Assessment and Mitigation: Regular use of risk assessment tools like WBGT and WCTI to evaluate environmental conditions and adjust activities to mitigate risks are fundamental as we already see. The publication propose the aplication of the follow information as a measure of prevention of cold and heat stress injuries.

Figure 1. Wind-Chill Temperature, based on the combination of air temperature and wind speed. Retrieved from pag. 3-9 and 3-10.

Figure 2. Heat stress management: Fluid replacement and work/rest guide. CAUTION: Hourly fluid intake should not exceed ~1 ½ liters. Daily fluid intake should not exceed 12 liters (or quarts). Retrieved from pag. A-2.

Figure 3. Heat stress management: Continuous work duration and fluid replacement guide. Retrieved from pag. A-3.

Learn more about this publication here.

Regarding this subject, we strongly recommend the following publications. They contain complementary information about the theme. We have shared only a few pieces of information that we consider extremely important:

1. ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance during Cold-Weather Exercise published in november 2021. (DOI:10.1249/JSR.0000000000000907).

System for Staging of Accidental Hypothermia

Figure 4. Revised Swiss system for staging of accidental hypothermia. Retrived from ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance during Cold-Weather Exercise.

Treatment algorithm for patients with accidental hypothermia

Figure 5. Treatment algorithm for patients with accidental hypothermia. Retrived from ACSM Expert Consensus Statement: Injury Prevention and Exercise Performance during Cold-Weather Exercise.

2. ACSM Expert Consensus Statement on Exertional Heat Illness: Recognition, Management, and Return to Activity published in april 2023. (DOI: 10.1249/JSR.0000000000001058).

The evaluation and field care of an athlete with suspected exertional heat illness

Figure 6. The evaluation and field care of an athlete with suspected exertional heat illness. Retrived from ACSM Expert Consensus Statement on Exertional Heat Illness: Recognition, Management, and Return to Activity.

3. Physiological Systems and Their Responses to Conditions of Heat and Cold by Sawka, Michael N.; Young, Andres J. in 2006 (here).