Heat Intolerance Problems Kambiz Behzadi, M.D. Orthopaedic Surgeon Fremont/Pleasanton

What Causes Heat Related Illness? Bodys failure to keep itself cool Bodys failure to keep itself cool Sweat/Evaporation releases heat Sweat/Evaporation releases heat Humidity impairs release of heat Humidity impairs release of heat Increased body temperature Increased body temperature Heat Illness Heat Illness

Heat Intolerance > 300 people die of heat related illness in U.S. > 300 people die of heat related illness in U.S. Heightened awareness in athletes Heightened awareness in athletes Identify athletes at risk Identify athletes at risk Not a disease Not a disease Accident waiting to happen Accident waiting to happen

Heat Intolerance Heat Stroke can occur in best athletes Heat Stroke can occur in best athletes Korey Stringer, Vikings, professional Korey Stringer, Vikings, professional Estrate Autin, Florida, college Estrate Autin, Florida, college

Heat Intolerance Preseason Football, Marathon, Soccer Preseason Football, Marathon, Soccer Mild to Fatal Mild to Fatal High Temperature + High Humidity High Temperature + High Humidity Preventable awareness, recognition, treatment Preventable awareness, recognition, treatment

Hypothalamus Bodys Thermostat Bodys Thermostat As temperature hypothalamus responds: As temperature hypothalamus responds: 1. Increase blood flow to skin 1. Increase blood flow to skin 2. Increase sweating 2. Increase sweating

Temperature Regulation Conduction: jumping into the pool Conduction: jumping into the pool Convection: standing in front of fan Convection: standing in front of fan Evaporation: water from liquid to gas Evaporation: water from liquid to gas Radiation: electromagnetic heat waves Radiation: electromagnetic heat waves

Temperature Regulation Conduction

Convection Convection

Temperature Regulation Sweating & Evaporation

Radiation Radiation

Sweating/Evaporation In hot a environment, Evaporation becomes the Primary source of Heat Dissipation In hot a environment, Evaporation becomes the Primary source of Heat Dissipation Humidity decreases our ability to get rid of Heat Humidity decreases our ability to get rid of Heat

Exercise Work + Heat Heat increases core body temperature Heat increases core body temperature Warm blood bathes the hypothalamus Warm blood bathes the hypothalamus Blood diverted from warm core to cool shell (conduction, convection, radiation) Blood diverted from warm core to cool shell (conduction, convection, radiation) Sweat glands release hypotonic saline solution (sweat) evaporation Sweat glands release hypotonic saline solution (sweat) evaporation

Physiology Exercise work + heat Hypothalamus Blood Flow Skin Sweat

Hot Environment Sweat/Evaporation Conduction Convection Radiation

Exercise in Heat Two Demands on Circulatory System Blood (Nutrients and Oxygen) to Working Muscle Blood (Nutrients and Oxygen) to Working Muscle Blood to Skin to Cool Body Blood to Skin to Cool Body

Heat and Exercise Muscle Muscle G.I. Tract Kidney Circulatory System Circulatory System Liver Brain Skin Skin

Early Heat Intolerance Shock : Weak pulse, low blood pressure, dizziness, syncope, headache, nausea, vomiting, lack of appetite, weakness Shock : Weak pulse, low blood pressure, dizziness, syncope, headache, nausea, vomiting, lack of appetite, weakness Temperature below 102 F or 39 C Temperature below 102 F or 39 C

Stressed Out Circulatory System Dehydration & Fluid Loss Dehydration & Fluid Loss Worsening State of Shock Worsening State of Shock

Heat Stress + Exercise Overwhelmed Cardiovascular System Heat Exhaustion Heat Exhaustion

Heat Stroke Break down cooling mechanism Increase core body temperature + Shock Damage to cells in body Multi-system failure Death

Heat Intolerance Problems Heat Syncope Heat Syncope Heat Cramps Heat Cramps Heat Exhaustion Heat Exhaustion Heat Stroke Heat Stroke

Heat Syncope Athlete stands still after exercise Athlete stands still after exercise Pooling of blood in extremities Pooling of blood in extremities Light-headed, dizzy, faint Light-headed, dizzy, faint Core body temperature is normal Core body temperature is normal Lie on ground, shaded area, legs elevated Lie on ground, shaded area, legs elevated Oral fluids usually not required Oral fluids usually not required Recovery rapid Recovery rapid

Heat Syncope Treatment

Heat Cramps Painful contractions large muscle groups ( legs, abdomen) Painful contractions large muscle groups ( legs, abdomen) Dehydration & Loss of balance between salt and water in muscle Dehydration & Loss of balance between salt and water in muscle Treatment: 1. Rest and Passive stretch 2. Fluid replacement (water, sports drink) Treatment: 1. Rest and Passive stretch 2. Fluid replacement (water, sports drink) Prevention: Adequate hydration before and throughout exercise Prevention: Adequate hydration before and throughout exercise

Heat Cramps Treatment

Heat Exhaustion Most common form of heat intolerance Most common form of heat intolerance Fatigue, weakness, sweating, nausea, diarrhea, mental status normal to slightly impaired Fatigue, weakness, sweating, nausea, diarrhea, mental status normal to slightly impaired Symptoms of mild shock Symptoms of mild shock Temperature < 102 F or 39 C Temperature < 102 F or 39 C

Heat Exhaustion Treatment Lie in cool, shaded area Lie in cool, shaded area Fluid replacement Fluid replacement IV Fluids IV Fluids Do not allow return to vigorous activity until normal body weight is reached Do not allow return to vigorous activity until normal body weight is reached

Heat Stroke True Medical Emergency True Medical Emergency Hyperthermia (Temp>105F or >40C) Hyperthermia (Temp>105F or >40C) Failure of Thermoregulatory Mechanism Failure of Thermoregulatory Mechanism Central Nervous System Dysfunction Central Nervous System Dysfunction Second most common cause of death in U.S. athlete Second most common cause of death in U.S. athlete

Animals Built-in Protective Mechanism

Exercise + Heat Mild Shock Fluid Loss and Fluid Loss and Shock Dehydration Shock Dehydration Overwhelming Temperature Heat regulatory Mechanism Metabolism Metabolism

Diagnosis Heat Stroke: Rectal Temp > 105 F Aggressiveness Aggressiveness Irritability Irritability Emotional Instability and hysteria Emotional Instability and hysteria Apathy Apathy Disorientation Disorientation Unsteady gait Unsteady gait Hot, dry skin Hot, dry skin Unconsciousness Unconsciousness

Treatment Heat Stroke Call Ambulance Call Ambulance Remove clothing Remove clothing Immerse in cool/iced water bath Immerse in cool/iced water bath Cover wet sheets and compress+fan Cover wet sheets and compress+fan Airway, Oxygen, Rehydration Airway, Oxygen, Rehydration Support Multi-organ failure Support Multi-organ failure

Prevention Acclimatization: bodys adaptation to heat stress, and increased capacity to work in high temperature and humidity Acclimatization: bodys adaptation to heat stress, and increased capacity to work in high temperature and humidity 7 days to several weeks 7 days to several weeks 30 minutes 2 hours 30 minutes 2 hours Lower resting body temperature Lower resting body temperature Increased plasma volume Increased plasma volume Lower threshold for sweating Lower threshold for sweating

Prevention Practice in early morning or late afternoon Practice in early morning or late afternoon Night games early in season Night games early in season Uniforms light weight, porous, light in color Uniforms light weight, porous, light in color Sleeves short and socks low Sleeves short and socks low Much skin exposed to air Much skin exposed to air

Prevention Hydration is key Hydration is key Free intake of fluids during games Free intake of fluids during games Regular fluid breaks no less than every half hour Regular fluid breaks no less than every half hour 1 pint (2 cups) for each 1 pound sweat lost 1 pint (2 cups) for each 1 pound sweat lost 10 oz. Every 30 minutes 10 oz. Every 30 minutes Only 50% fluid loss made up by thirst (encourage fluid intake between and during sessions) Only 50% fluid loss made up by thirst (encourage fluid intake between and during sessions) Events < 90 min, electrolyte replacement usually unnecessary Events < 90 min, electrolyte replacement usually unnecessary

Prevention Glucose concentration < 5% to 8% Glucose concentration < 5% to 8% Dilute twofold Dilute twofold 10% glucose (soft drinks and juices) cause stomach cramps, nausea, diarrhea, slow gastric emptying 10% glucose (soft drinks and juices) cause stomach cramps, nausea, diarrhea, slow gastric emptying Fructose (fruits) absorbed slowly and causes G.I. distress Fructose (fruits) absorbed slowly and causes G.I. distress

Prevention Sports drinks Sports drinks Replacement glycogen in (muscle and liver) in exercise lasting > 90 minutes Replacement glycogen in (muscle and liver) in exercise lasting > 90 minutes Dilute solution Sodium and Glucose increase absorption of water in small intestine Dilute solution Sodium and Glucose increase absorption of water in small intestine

Prevention Cumulative Hypohydration Cumulative Hypohydration Weigh before and after each practice Weigh before and after each practice No player should be allowed to return to play until fluid loss is replaced and normal weight is achieved No player should be allowed to return to play until fluid loss is replaced and normal weight is achieved

Electrolyte Make-up Goal to replace sweat that has evaporated Goal to replace sweat that has evaporated Sweat = water + small concentration of salts and other electrolytes Sweat = water + small concentration of salts and other electrolytes Concept: Sport drink = Sweat Concept: Sport drink = Sweat Evaporated sweat replaced before next exercise Evaporated sweat replaced before next exercise Normal diet replaces lost electrolytes Normal diet replaces lost electrolytes Electrolytes in drinks increase absorption of water Electrolytes in drinks increase absorption of water