human performance in hot environments lt anthony artino aeromedical safety officer comaewwingpac

Human Performance in Hot Human Performance in Hot EnvironmentsEnvironments

LT Anthony ArtinoLT Anthony Artino

Aeromedical Safety OfficerAeromedical Safety Officer

COMAEWWINGPACCOMAEWWINGPAC

OVERVIEWOVERVIEW

• Heat injury statisticsHeat injury statistics

• Physiological response to heatPhysiological response to heat

• Heat stressHeat stress

• Preventing heat stressPreventing heat stress

Why E-2C’s Shouldn’t Fly Low!Why E-2C’s Shouldn’t Fly Low!

HEAT INJURY STATISTICSHEAT INJURY STATISTICS

• Each year many people die from heat-related Each year many people die from heat-related injuries.injuries.

– Average Death Count Average Death Count 60 people/year 60 people/year

– Heat Wave Death Counts...Heat Wave Death Counts...• Summer 1980 = 1700 peopleSummer 1980 = 1700 people• Summer 1995 = 1021 peopleSummer 1995 = 1021 people

– Sept Climate Averages for Sept Climate Averages for Puerto RicoPuerto Rico……• Temp Highs = 92Temp Highs = 92ooFF• Relative Humidity = 75%Relative Humidity = 75%

National Weather Service

PHYSIOLOGICAL PHYSIOLOGICAL RESPONSE TO HEATRESPONSE TO HEAT

VasodilationVasodilation– Blood vessels on the surface of the skin Blood vessels on the surface of the skin

dilatedilate– Blood flow to the surface of the skin Blood flow to the surface of the skin

increasesincreases– Heat is dissipated to the environment via Heat is dissipated to the environment via

conduction, convection, radiation and/or conduction, convection, radiation and/or evaporationevaporation of sweat of sweat

PHYSIOLOGICAL PHYSIOLOGICAL RESPONSE TO HEATRESPONSE TO HEAT

SweatingSweating– Evaporation of sweat is our body’s primary Evaporation of sweat is our body’s primary

means of losing heatmeans of losing heat– Our body’s ability to produce enough sweat Our body’s ability to produce enough sweat

is directly related to our hydration levelis directly related to our hydration level– Sweat production during strenuous Sweat production during strenuous

workouts in hot environments can equal workouts in hot environments can equal 1 quart/hour 1 quart/hour

HEAT STRESSHEAT STRESS

• Heat stress is a Heat stress is a generalgeneral term for all heat- term for all heat-related disordersrelated disorders

• Heat stress occurs when the body builds up Heat stress occurs when the body builds up more heat than it can handlemore heat than it can handle

• Influencing factors are…Influencing factors are…– High temperaturesHigh temperatures High humidityHigh humidity– Heavy workloadsHeavy workloads DehydrationDehydration


• Heat RashHeat Rash– An early sign of potential heat stressAn early sign of potential heat stress– Associated with humid environments where Associated with humid environments where

skin and clothing remain damp due to skin and clothing remain damp due to unevaporated sweatunevaporated sweat

– Sweating production may be compromisedSweating production may be compromised– Treatment includes…Treatment includes…

• Keeping skin clean and dry for at least 12 hoursKeeping skin clean and dry for at least 12 hours• Applying a mild lotionApplying a mild lotion


• Heat CrampsHeat Cramps– Muscle cramps caused by fluid and salt Muscle cramps caused by fluid and salt

imbalance during physical exercise in a hot imbalance during physical exercise in a hot environmentenvironment

– Treatment includes…Treatment includes…• Firm pressure or gently massaging the affected Firm pressure or gently massaging the affected

musclemuscle• Resting in a cooler environment (shade)Resting in a cooler environment (shade)• Re-hydrating with water and/or sports drinksRe-hydrating with water and/or sports drinks


• Heat ExhaustionHeat Exhaustion– Basically a water volume problem in the body Basically a water volume problem in the body

caused by inadequate fluid replacement and caused by inadequate fluid replacement and profuse sweatingprofuse sweating

– Body is having difficulty maintain BP and Body is having difficulty maintain BP and sending blood to the skin’s surfacesending blood to the skin’s surface

– Symptoms may include…Symptoms may include…• Fatigue, weakness, and/or faintingFatigue, weakness, and/or fainting• Dizziness, nausea, and/or headacheDizziness, nausea, and/or headache• Clammy skin (may be flushed or pale)Clammy skin (may be flushed or pale)


• Heat ExhaustionHeat Exhaustion– Treatment includes…Treatment includes…

• Moving to a cooler environment (shade)Moving to a cooler environment (shade)• Lying down on a flat or slight declined surfaceLying down on a flat or slight declined surface• Applying cool, moist clothes and/or fanningApplying cool, moist clothes and/or fanning Re-hydrating with water and/or sports drinksRe-hydrating with water and/or sports drinks• Call a doctor, especially if victim vomits or faintsCall a doctor, especially if victim vomits or faints


• Heat StrokeHeat Stroke– Life-threatening condition of increased core body Life-threatening condition of increased core body

temperature (hyperthermia >105 temperature (hyperthermia >105 ooF)F)– This is a medical emergency! (coma or death)This is a medical emergency! (coma or death)– Body’s heat-regulating mechanism is overwhelmedBody’s heat-regulating mechanism is overwhelmed– Symptoms may include…Symptoms may include…

Hot skinHot skin - the key to identification!! (dry or wet) - the key to identification!! (dry or wet)• Increased pulse and respiratory rateIncreased pulse and respiratory rate• Headache, dizziness, abdominal distress, mental Headache, dizziness, abdominal distress, mental ’s’s


• Heat StrokeHeat Stroke– Treatment includes…Treatment includes…

• Calling 911Calling 911• Immediate active cooling of body, including…Immediate active cooling of body, including…

– Move patient to a cooler environmentMove patient to a cooler environment– Pouring cool water on the extremitiesPouring cool water on the extremities– Wrapping in wet, cool clothsWrapping in wet, cool cloths– Whole body immersion in cool (not cold) waterWhole body immersion in cool (not cold) water

• Re-hydrating with water and/or sports drinksRe-hydrating with water and/or sports drinks• CPR if necessaryCPR if necessary

PREVENTING HEAT PREVENTING HEAT STRESSSTRESS

What What NOTNOT to do to do HydrationHydration AcclimatizationAcclimatization Physical FitnessPhysical Fitness Proper ClothingProper Clothing

““Prevention is the best medicine.Prevention is the best medicine.””


• What What NOTNOT to do to do– Don’t drink sugary fluids (>10% Carbo) or Don’t drink sugary fluids (>10% Carbo) or

carbonated beveragescarbonated beverages– Don’t drink alcohol or caffeinated Don’t drink alcohol or caffeinated

beveragesbeverages– Don’t damage your skin with a sunburnDon’t damage your skin with a sunburn– Don’t overdo itDon’t overdo it


• HydrationHydration– Staying well hydrated is your best defense Staying well hydrated is your best defense

against all heat stressagainst all heat stress– Urine output and color is the best indicator of Urine output and color is the best indicator of

proper hydrationproper hydration• Urination should occur oftenUrination should occur often

• Urine should be light colored to clearUrine should be light colored to clear

– Thirst is a Thirst is a poor indicatorpoor indicator of dehydration of dehydration• The thirst mechanism is slowThe thirst mechanism is slow

• Once you feel thirsty, you’re already dehydrated!Once you feel thirsty, you’re already dehydrated!


• HydrationHydration– Average person requires about 3-4 quarts Average person requires about 3-4 quarts

of fluid per day in a hot environmentof fluid per day in a hot environment– In more extreme environments, 3-4 gallons In more extreme environments, 3-4 gallons

may be requiredmay be required– Drinking frequently in small amounts is Drinking frequently in small amounts is

more effective than drinking large amounts more effective than drinking large amounts at one timeat one time


• HydrationHydration– Sugary fluids and carbonated beverages Sugary fluids and carbonated beverages

actually decrease water absorptionactually decrease water absorption– Sports drinks (6-8% Carbo) may increase Sports drinks (6-8% Carbo) may increase

absorption and can improve long-term absorption and can improve long-term performance (taste is also an issue)performance (taste is also an issue)

– When in doubt….DRINK WATER!When in doubt….DRINK WATER!


• Acclimatization (to heat)Acclimatization (to heat)– Physiological adaptations that give the body an Physiological adaptations that give the body an

added ability to tolerate extreme heatadded ability to tolerate extreme heat– Accomplished through progressive degrees of Accomplished through progressive degrees of

heat exposure and physical exertionheat exposure and physical exertion– Takes approximately 3 weeks to completeTakes approximately 3 weeks to complete– Majority of the positive changes occur within Majority of the positive changes occur within

the the first weekfirst week


• Acclimatization (to heat)Acclimatization (to heat)– Physiological adaptations include…Physiological adaptations include…

• Increase sweat production (>twofold increase)Increase sweat production (>twofold increase)– Non-acclimatized - maximum 700mL of sweatNon-acclimatized - maximum 700mL of sweat– Acclimatized - maximum 2000mL of sweatAcclimatized - maximum 2000mL of sweat

• Decreased loss of salt in sweat and urineDecreased loss of salt in sweat and urine– i.e. sweat and urine are more dilutei.e. sweat and urine are more dilute– Retained salt helps body hold more water overallRetained salt helps body hold more water overall


• Physical FitnessPhysical Fitness– Tolerance to heat is increased in Tolerance to heat is increased in

individuals with high aerobic fitnessindividuals with high aerobic fitness– Rate of acclimatization is a function of Rate of acclimatization is a function of

fitnessfitness– Unfit individuals take up to 50% longer to Unfit individuals take up to 50% longer to

acclimateacclimate


• Proper ClothingProper Clothing– Loose fitting, non-starched clothing Loose fitting, non-starched clothing – Starch blocks fabric pores and restricts air Starch blocks fabric pores and restricts air

circulation circulation – Light clothing also protects against sun Light clothing also protects against sun

burnsburns

SUMMARYSUMMARY

• Heat injury statisticsHeat injury statistics

• Physiological response to heatPhysiological response to heat

• Heat stressHeat stress

• Preventing heat stressPreventing heat stress

RESOURCESRESOURCES

• Centers for Disease Control and Prevention(CDC). Centers for Disease Control and Prevention(CDC). Extreme Heat: A Extreme Heat: A Prevention Guide to Promote Your Personal Health and SafetyPrevention Guide to Promote Your Personal Health and Safety, U.S. , U.S. Department of Health and Human Services, 1996.Department of Health and Human Services, 1996.

• Curtis, Rick. Curtis, Rick. Outdoor Action Guide to Heat-Related Illnesses & Fluid Outdoor Action Guide to Heat-Related Illnesses & Fluid BalanceBalance, Princeton University, 1997., Princeton University, 1997.

• Guyton, Authur. Guyton, Authur. Textbook of Medical Physiology: Textbook of Medical Physiology: Body Temperature, Body Temperature, Temperature Regulation, and FeverTemperature Regulation, and Fever, W.B. Saunders Company, 1991., W.B. Saunders Company, 1991.

• Reinhart, Richard. Reinhart, Richard. Basic Flight Physiology: Environmental StressesBasic Flight Physiology: Environmental Stresses, , McGraw-Hill, 1996.McGraw-Hill, 1996.

• Tueller, John. Tueller, John. Prevention of Heat Stress InjuriesPrevention of Heat Stress Injuries, Navy Message, , Navy Message, DTG 280730Z APR 99.DTG 280730Z APR 99.

• Zhao, Wei & Kersting, Ann. Zhao, Wei & Kersting, Ann. Preventing Heat Stress in AgriculturePreventing Heat Stress in Agriculture, , Rutgers Cooperative Extension.Rutgers Cooperative Extension.

human performance in hot environments lt anthony artino aeromedical safety officer comaewwingpac

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