09 Heat Stress... Flashcards
It is important that body temp is maintained within approx. _________ of each person’s normal value because larger deviations dramatically affect biological function.
1.5 degrees
Body can transfer heat to and from the surroundings through:
- Evaporation
- Radiation
- Conduction
- Convection
Two physiological processes our bodies use to transfer heat and maintain thermal balance
- Increasing blood flow to the surface of the body (skin) so heat can mostly be lost through radiation and convection along with conduction
- Evaporative cooling that occurs when sweat is evaporated from the skin
The Magnitude of the increase in core temperature depends on (Three Major Factors Contributing To Increased Body Temp)
- Physical work performed
- PPE worn
- Ambient temp
Changes in core temp depend on:
- Physical work
- Length of time spent working
- number of evolutions (training)
- Time of rehab or recovery between each evolution
- How recovery time was used
PPE adds to heat gain because:
- It is heavy (50-70 pounds)
- Movement requires greater metabolic/musculara work
- Interfering with heat dissipation (insulative)
What is essential for proper cooling and physiological recovery?
Removal of PPE
Ambient Conditions that can contribute to increased body temperatures:
- Air temp
- Relative humidity
- Sun exposure
- Wind speed
Core temps were found to increase by:
- Over 3 degrees for FF conducting overhaul and outside vent ops (16-19 minutes)
- Approx. 2 degrees during fire attack and search and rescue tasks (10-11 minutes)
Working in hot and humid conditions can lead to fluid loss of _________ per hour from sweating and firefighting.
1-2 liters
Sweat loss of _____ per hour has been reported during work in a hot environment while wearing PPE.
2.8 pounds
Heat Illnesses (Check p. 142)
- Heat Rash
- Heat Cramps
- Heat Exhaustion
- Heatstroke
- Rhabdomyolysis
Heat Exhaustion should be treated aggressively by:
- Removing gear
- Moved to cool shaded area, upwind
- Active and aggressive cooling (misting fans, forearm immersion, or full body submersion
- Rehydration
What is the most severe form of heat illness?
Heatstroke
Heatstroke occurs when there is a depletion of salt and water and an impaired ability to effectively thermoregulate.
What is often the first sign of heatstroke?
Central Nervous System Dysfunction
- Confusion
- Irritability
- Seizure
- Cardiovascular Collapse
Rhabdomyolysis
Breakdown of muscle as a result of damage to the tissue.
- Breakdown or death of muscle allows electrolytes and proteins (esp. creatine kinase and myoglobin) to leak into the blood stream.
- Altered blood stream is dangerous for heart, brain, and kidneys.
Risk factors for heat illness
- Poor physical condition
- Excess Body weight
- Dehydration and salt depletion
- Chronic disease
- Minor illness
- Skin problems
- Medications
- Prior heat exposure
- Prior heat injury
- Recent alcohol use
- Genetics
- Lack of heat acclimatization
HR was approx. ________ higher when wearing PPE compared with weighted vest (doing same exercise and carrying same weight)
47 bpm
Steps to combat negative consequences of heat stress
- Proper hydration
- Physical fitness
- Engaging in incident scene rehabilitation
What is one of the most powerful protectors of health and a vital preventative strategy for reducing negative heat-related consequences?
Physical fitness
Primary goal of rehab?
Ensure physical and mental condition of members operating at the scene do not deteriorate to a point that affects the safety of others or jeopardizes the integrity of the operation.
What is the goal of cooling?
Decrease core body temp, not just to make the FF feel cooler.
