Exposure to extreme heat is the reality of unit preparation for operational missions. Many heat injuries are preventable, and none need be fatal. Leaders must assess unit's missions and training requirements against the risk associated with operating in warm weather environments. Early recognition and treatment of Soldiers presenting with symptoms of heat injuries are key to saving lives.
Heat Illness Risk Management Slides for Unit/Installation Training Applications - The key information from this website has been placed in this slide deck for field use to create annual training and predeployment medical briefings. (Note: When selecting "Open" file, some users may receive a Windows Security pop-up message; please select "Cancel" and the presentation should load.)
If you have additional questions, please contact the APHC Injury Prevention Program at:Email Address: email@example.com
3 REASONS WHY YOU NEED TO KNOW ABOUT HEAT ILLNESS
1. Heat illness is a threat to individual health and to military operational success:
Despite well documented and effective techniques for preventing heat illnesses, they continue to be a threat to Soldiers in training and combat.
Over 1,600 heat casualties in 2012 Army Active component required medical attention and/or lost duty time.
Even mild heat illness and dehydration can significantly degrade performance:
Ø Degrades performance
Ø Losing 4% of body weight from dehydration degrades physical performance 50%
Ø This 4% body weight loss is possible in less than 2 hrs!
Ø Increases core body temp
Ø Every 1% loss of body weight increases core temp .10-.23°C or .18-.40°F (increasing risk of more serious heat illness)
2. Heat illness is preventable!
3. Training is required!
TYPES OF HEAT ILLNESSES
Exertional Heat Illness ("EHI") refers to a spectrum of disorders (e.g., cramps, heat exhaustion, heat injury, heat stroke) resulting from total body heat stress. While there is a range of adverse effects that can result from the body over-heating, the 2 major kinds of heat illnesses that are referred to as heat casualties are: forms of heat exhaustion (can be milder or more severe), while more severe cases are heat stroke (most severe form of heat illness and possibly fatal).
“Canaries in the coal mine” - need to catch these before they get to a more extreme case of heat stroke - catch early as they need rest/water/evaluation and possible medical care.
Ø Clumsy/unsteady walk
Ø Muscle cramps
Ø Rest Soldier in shade
Ø Loosen uniform/remove head gear
Ø Have Soldier drink 2 quarts of water over 1 hour
Ø Evacuate if no improvement in 30 minutes, or if Soldier's condition worsens
Medical emergency – these cases already have abnormal brain function and can be fatal – initiate rapid cooling and EVAC!
Ø Profuse sweating
Ø Convulsions and chills
Ø Confusion, mumbling - do mental check questions to see if brain is working correctly
Ø Passing out (unconscious)
Ø COOL and CALL!! – the faster the body is cooled, the less damage to the brain and organs
Ø Strip (if possible, ensure a same gender helper is present)
Ø Rapid cool (ice sheets)
§ Cover all but face with iced sheets.
§ Ensure the iced sheet is soaked prior to applying to the casualty.
§ Fan the entire body.
§ Stop cooling if victim starts shivering.
Ø Call for evacuation
Ø Continue cooling during transport
Ø NOTE: The same person should observe the Soldier during cooling and evacuation in order to spot symptom changes.
HYPONATREMIA "Water Intoxication"
This is a Medical Emergency – EVAC immediately, can be mistaken for Heat Stroke, though treatment is very different. NOTE: condition most often occurs in TRADOC IET units, especially during BCT/OSUT.
Ø Mental status changes
Ø History of consumption of large volume of water
Ø Poor food intake
Ø Abdomen distended/bloated
Ø Large amounts of clear urine (if urine)
Ø Do not give more water or IV! If awake, allow Soldier to consume salty foods or snacks
Ø Evacuate immediately
REACTING TO A HEAT ILLNESS CASUALTY:
Remember "M.A.D.E. in the Shade":
MOVE victim to cool location (e.g., shade, A/C car, building)
ASSESS victim to determine type of EHI
Risk level (red beads or risk factors)
- Hydration (550 cord) to check for hyponatremia
- Mental status (for heat stroke)
- Designate single person to continue monitoring. It is critical that a specific person is assigned to STAY with victim and continuously monitor all changes including mental status – Even the slightest changes that can occur in minutes may not be noticed if different personnel are checking victim – these slight changes can be critical in ensuring the best outcome for the victim.
DECIDE which EHI and take proper management approach
Hyponatremia: evacuate immediately
EVALUATE other Soldiers and adjust training as necessary
- Heat Exhaustion: rest in shade, rehydrate
- Heat Stroke: begin rapid cooling, evacuate immediately
WET BULB GLOBE TEMPERATURE
Wet Bulb Globe Temperature (WBGT) is a composite temperature used to estimate the effect of temperature, humidity, wind speed (‘wind chill’), and visible and infrared radiation (e.g., sunlight) on humans. The WBGT index was developed in 1956 by the United States Marine Corps at Parris Island to reduce heat stress injuries in recruits. It is determined with special equipment and calculated to reflect components of air, humidity and wind that affect ‘actual temperature’ experienced by personnel: WBGT is derived from the formula: 0.7Tw + 0.2Tg + 0.1Td
Tw = Natural wet-bulb temperature (with dry-bulb temperature indicates humidity)
Tg = Globe thermometer temperature (also known as black globe thermometer)
Td = Dry-bulb temperature (actual air temperature)
Wet Bulb Globe Temperature (WBGT) Categories
Ø Add 5°F for rucksack or body armor
Ø Add 10°F if in MOPP 4
RISK FACTORS FOR HEAT ILLNESS
- Higher temperature
- High humidity (WBGT)
Lack of Acclimatization: Acclimatization requires aerobic exercise in a warm environment. The body needs to adjust to environmental heat stressors prior to high exertion activities; simply being outside doing normal activities is not sufficient.
- High exertion
- Heavy loads/gear
- Repeated strenuous days
NOTE: Hot weather is a key risk factor for heat injuries, HOWEVER:
--> Heat illnesses can occur under green flag temperature conditions due to previous days' conditions and dehydration.
Individual Risk Factors to EHI:
- Poor fitness (2 mile run > 16 mins)
- Body mass index (BMI) > 26
- Age > 40
- Gender (female)
- Minor illness
- Medication: Antihistamines (e.g., Benadryl, Atarax, CTM), decongestants (e.g., Sudafed); high blood pressure (e.g., diuretics, beta blockers); psychiatric drugs (e.g., tricyclic antidepressants, antipsychotics). NOTE: Despite certain policies, to date (2013) there is currently NO scientific evidence that caffeine, energy drinks, "fat burners" or dietary supplements affect the body's ability to regulate heat.
- Alcohol in the past 24 hours
- Prior heat injury
- Skin rash, sunburn, or poison ivy
- Blood donation (< 3 days)
- Sleep deprived
- Highly motivated - the desire to meet or exceed standards may lead some Soldiers to continue to push themselves as early signs/symptoms of EHI occur. These Soldiers should not be discouraged from pushing themselves but cadre should be aware of their tendency so that they can be watched more closely.
FIVE STEPS OF RISK MANAGEMENT TO PREVENT EHI
1. IDENTIFY THE HAZARDS:
Know the Wet Bulb Globe Temperature (WBGT)
Know the Total Body Heat Stress = Total Heat Load on an invidivual =
1) Heat generated by the body (due to metabolism and activity)
2) + Heat gained from the environment
3) - Heat lost in the environment
Know the Risk Factors for EHI. Most commonly thought of risk factors are the climate/temperature and the level of physical activity/exertion, however there are numerous individual risk factors to be aware of - especially consider when a single individual has more than one of the listed risk factors.
2. ASSESS HAZARDS:
Utilize the WBGT temperature index
- Add 5°F for rucksack or body armor
- Add 10°F if in MOPP 4
Know your Soldiers - Identify individuals at increased risk
Monitor hydration status - Assess morning and evening as well as during training
Factor in previous days’ conditions & activities - Consider temperature, activity levels, illnesses
Use a risk management matrix to document and manage decisions
H Heat category past 3 days
E Exertion level past 3 days
A Acclimation/other individual risk factors
T Time (length of exposure and recovery time)
3. DEVELOP CONTROLS:
Plan in advance:
- Estimate heat risk level 1 day prior
§ Previous 2 days of heat exposure & Predicted Heat Category for that day
§ Training events (distance, pace, breaks, etc.) and Work-rest cycle, hydration guidelines, etc.
§ Location, Time of day
Adjust activity distances, durations, pace, and loads
§ Conduct high-intensity training in cooler morning hours
- Ensure proper resources at appropriate locations
§ Functional WBGTs
§ Ice sheets (in cooler filled 1/3 water, 2/3 ice)
§ Medical: resources, locations, communication systems
Establish SOPs, train, and test Soldiers:
Identify how to monitor hydration & high risk personnel
- Heat Illness prevention and Hydration cards and sunscreen to all
- Place Heat Illness Prevention posters and urine guides in bathrooms, bulletin boards, DFAC, training areas, etc.
Prepare communication capabilities, water, food/snacks, medical, and evacuation support:
- Recommend commercial electrolyte beverages (diluted to half-strength) in high-risk months (or when daily water consumption exceeds 1-1.5 gallons/day)
- Ensure water control points throughout designated training areas.
- Ensure canteens/hydration packs are properly cleaned daily (FM 21-10), especially when using flavored commercial electrolyte beverages.
- Pre-plan changes if METT-TC/Heat Category changes or if heat casualties occur
4. IMPLEMENT CONTROLS:
Monitor Hydration and Personnel
- Identify High risk personnel
- Buddy system: Assign Low risk personnel to High risk personnel
- Track individual hydration status
§ Use parachute 550 cord or Ogden cord tied to button hole, ear plug case, or shoe laces
§ Daily intake (1 knot/black bead per canteen)
§ Urine monitoring techniques (know limitations)
- Track High risk personnel: Use red beads or red armband/Velcro patch for "at-risk" Soldiers
Electrolyte drinks and meal intake
Change events and activities to minimize heat load
- Place water at key points e.g., at land nav objectives
- Provide and monitor:
- Avoid back-to-back strenuous days, especially Category 4-5
- Modify time of day - complete activities earlier/later
§ Wide spacing between Soldiers (e.g., 60 feet)
§ Reduce pace and/or distance
§ Shade Soldiers whenever possible
- Reduce clothing and load:
§ Backpacks, body armor, helmets, etc. (training)
Dump excess heat
§ Allow/provide field shower
§ Cool overnight temperatures (fans, air conditioning, cool showers)
5. SUPERVISE AND EVALUATE:
Be familiar with signs/symptoms of EHI
- Look for mild signs/symptoms à stop from progressing
- Take immediate action when EHI is observed or suspected
- When in doubt, call 911 and begin cooling!!
Spot Check TROOPS/CADRE/JUNIOR LEADERS
- “What are heat illness signs/symptoms?”
- “Do you have your HIP (Heat Injury Prevention) Pocket Guide card?"
- “What is the current Heat Category?”
- “Who is at risk?” ”Who is their buddy?”
- “What actions would you take if … ”
- Is water available and accessible?
- Are rapid cooling supplies on-hand?
- Do you have commo with medical support?
Spot check medical support
- Check equipment, personnel, evacuation vehicle, communication, ice sheets.
- If no organic medical support, check for coordination of alternatives (gate access for off-post EMS, travel time, procedures, etc.)
If a heat injury occurs, stop training and assess situation
Monitor food intake (food/salty snack every 4 hrs or less).
- Confirm Battle Buddy System is in place.
- Check Ogden cords for water intake. Are they drinking BEFORE PT in morning?
- Monitor urine output (e.g. ‘color test’, and/or Soldiers should urinate a full bladder every 2-3 hours)
- Ask questions that require clear thinking (What day is it? Where are you?).
- Look for Soldiers who are visibly ‘wilting’ or struggling.
- Look for Soldiers bypassing controls (e.g. not drinking in order to have a full canteen for an inspection).
This icon identifies links to external web sites that will open in a new browser window. See the External Links Disclaimer link at the bottom of this page.
Some linked files require specific plug-ins to open. To download plug-ins, see the File Formats Used on This Site link at the bottom of this page.
Heat Injury References
Heat Injury Prevention Products
(Create an account to download or order the following products from the Health Information Products eCatalog.)