1	HEAT ILLNESS AHSAA Alabama All Stars Sports Week June 15, 2009 JAMES B. ROBINSON, M.D. Head Team Physician University of Alabama
2	HEAT ILLNESS Introduction Physiology Types of Heat Illness Treatment Prevention
3	Introduction Heat Illness is a major concern for athletes participating in hot and/or humid conditions. Accounts for huge time-loss from participation in competitive athletic competitions
4	Heat Related Deaths 2008 4 High School 3 College 1960-1969 = 34 1970-1979 = 31 1980-1989 = 13 1990-1999 = 15 2000-2005 = 13 2006-2008= 13
5	PHYSIOLOGY
6	Thermoregulation A complex interaction between the CNS, cardiovascular system, and the skin.
7	PHYSIOLOGY Winslow Equation of Thermoregulation S = M +/- R +/- K +/- Cv - E S = Stored Heat M = Metabolic Heat Produced R = Heat from radiation K = Heat from Conduction Cv = Heat from Convection E = Evaporative Heat Loss
8	Metabolic Heat Produced Basal metabolic heat production (fasting): 60-70 kcal/hr 50% from internal organs Exercise metabolic heat production: 1000 kcal/hr 1200-1500 kcal/hr in elite athletes 90% from muscle metabolism Core temperature would increase 1 C with every 5-8 minutes of exercise
9	Heat from Radiation The energy transferred to or from and object via electromagnetic radiation from higher to lower energy surfaces. Heat from the sun! 150 kcal/hr Heat gain if > 96 degrees
10	Heat from Conduction The transfer of heat from a warmer to a cooler object through direct contact. Heat produced in muscle is transferred to circulating blood as long as core temperature is lower. Ice Packs Water baths- water conducts heat 25X faster than air Cold towels Cold benches, TMS shoulder pads
11	Heat from Convection The transfer of heat from an object to the surrounding air. Moving air from fans, wind, cycling Rate of heat loss can vary 5 fold between resting in still air and running on a breezy day. Minimal heat loss, if any, on a hot day
12	Evaporation The transfer of heat by the vaporization of sweat, and from respiration. The most efficient means of heat loss! Is dependant upon: Humidity Velocity of moving air Surface area exposed Sweat rate Effectiveness is diminished when humidity is > 60%
13	Evaporation Evaporation decreases as total body water decreases with dehydration and decreased blood flow to periphery and thus decreased sweat produced. Clothing and equipment reduce surface area and thus reduce evaporation: increases core temp, weight loss, heart rate Football uniform reduces body surface area for evaporation by 60%
14	Evaporation Sweat Rate Unacclimated athlete = 1 L/hr = 500 kcal/hr Acclimated athlete = 3 L/hr = 1500 kcal/hr Can be affected by: Medications: diuretics, amphetamines, cocaine, PCP, LSD Medical conditions: scleroderma, burns, cystic fibrosis Ointments, lotions
15	ACCLIMATIZATION Physiologic process by which an individual becomes able to tolerate work in a hot environment. Becoming “Thermal efficient” Usually takes 5-10 days - maximum acclimatization takes 3 months. Fluid and salt increase heat acclimatization.
16	TYPES of HEAT ILLNESS
17	HEAT ILLNESS Exercise associated muscle cramps (heat cramps) Heat syncope Exercise exhaustion (heat exhaustion) Exertional heat stroke Exertional hyponatremia Exertional rhabdomyolysis
18	HEAT CRAMPS An acute, painful, involuntary muscle contraction that presents during or after intense exercise. Causes: Dehydration Electrolyte imbalances (sodium chloride)- acclimatized athletes lose 14 grams NaCl Neuromuscular fatigue Anxiety Acid/base disturbances ( hyperventilation)
19	HEAT CRAMPS Treatment Remove from activity Replace fluids Replace salt (too little, too late) Stretch Massage (ice) I.V. fluids Others: Calcium gluconate, Quinine, I.V. Valium, pinch thumb web space, lip
20	HEAT SYNCOPE A feeling of lightheadedness or dizziness that occurs when a person is exposed to high environmental temperatures. Usually occurs during the first 5 days of acclimatization before blood volume expands.
21	Heat Syncope Signs and Symptoms Syncope Dizziness Tunnel vision Pale or sweaty skin Decreased pulse Normal rectal temperature
22	HEAT SYNCOPE Treatment Move to shaded area Monitor vital signs Trendelenburg position Rehydrate
23	EXERCISE (HEAT) EXHAUSTION The inability to continue exercise associated with: Heavy sweating Dehydration Sodium loss Energy depletion
24	HEAT EXHAUSTION Signs and Symptoms TBW loss of > 5% Nausea Anorexia Diarrhea Decreased urine output Rectal temperature: 97-104 degrees Pallor Persistent muscular cramps Urge to defecate Weakness Fainting Dizziness Headache Hyperventilation
25	HEAT EXAUSTION Treatment Move to shaded area Measure rectal temperature Remove excess clothes Fans, ice, ice towels Rehydrate I.V. fluids if situation worsens or rapid recovery is necessary. RTP 24-48 hours if no LOC and at baseline body weight.
26	EXERTIONAL HEAT STROKE Elevated core temperature ( >104 degrees) associated with signs of organ system failure due to hyperthermia. Life threatening!
27	EXERTIONAL HEAT STROKE Signs and Symptoms Coma ~ 70% Acute renal failure Rhabdomyolysis Bleeding (DIC) Pancreatitis/ GI bleed Mortality ~ 80% Temperature >104 rectal Fast heart rate Low blood pressure Sweating Rapid breathing Altered mental status Vomiting Diarrhea Seizures
28	EXERTIONAL HEAT STROKE Treatment Measure rectal temperature Lower temperature as rapidly as possible!! Place in a tub of ice water (temp=35-59F) remove when temp <102 (0 fatalities in 252 military personnel) 911- to Emergency Room ASAP! Cool I.V fluids, ice bags to neck, axilla, groin ABCs RTP = normal renal function, CPK, normal GXT At increased risk for future heat strokes
29	EXERTIONAL HYPONATREMIA A rare condition that occurs in athletes that participates for > 4 hours where the serum sodium level drops below 130 mmol/L. Ingestion of too much low salt fluids (water intoxication) and sweat sodium losses not replaced.
30	EXERTIONAL HYPONATREMIA Signs and Symptoms Serum Na+ <130mmol/L Extremity edema Pulmonary edema Cerebral edema Seizures Death Disorientation Altered mental status Headache Vomiting Lethargy Normal hydration state Temperature <104 F
31	EXERTIONAL HYPONATREMIA Treatment Prevention: Decrease fluid ingestion Replace sodium Ingest fluids with adequate sodium Transport to E.D. I.V. fluids = 3% NS No oral fluids RTP = normal serum Na+, education, salt replacement protocol (salt tabs etc.)
32	EXERTIONAL RHABDOMYOLYSIS A degeneration of skeletal muscle caused by excessive exercise First identified in 1988 Can be confused with heat stroke Usually only occurs on the first few days of strenuous unaccustomed exercise
33	Exertional Rhabdomyolysis Risk Factors Sickle Cell Trait Carbohydrate loading Dehydration Heat Diuretics
34	Exertional Rhabdomyolysis Signs and Symptoms Elevated CPK Hyper K+ Hyper PHO4 Hypo Ca++ Hyperuricacidemia Elevated Creatinine Exposure to strenuous exercise Muscle pain Weakness Swelling Myoglobinuria Renal Failure Coca-Cola colored urine
35	Exertional Rhabdomyolysis Treatment I.V. Fluids Dialysis Correct electrolyte imbalances RTP: CPK normal Renal function normal No muscle soreness Prevention!
36	PREVENTION
37	HEAT ILLNESS Prevention Emergency Plan Nearest Emergency facility, transportation, communications, cool tub, rectal thermometer Pre-participation physical exam - identify previous heat related problems Adequate acclimatization = 7-14 days Educate - athletes, coaches, parents Well balanced diet, adequate sleep, avoiding drugs and alcohol
38	HEAT ILNESS Prevention Monitor environmental conditions: Ambient temperature Relative humidity Local weather reports National Weather Service Airport reports Sling psychrometer Wet-Bulb Globe Temperature (WBGT) Practice times early morning or evening
39	WBGT
40	WBGT Remember these guidelines were for athletes in shorts and shirts, must adjust for equipment. Would never practice or play in the South!
41	HEAT ILLNESS Prevention Weigh athletes before and after practice. “a pint’s a pound…” Replace fluid lost during activity. Monitor urine color and volume. Have ice bags available Adequate cold fluids available. Rest periods- adjust for temperature and place in shade if possible. Remove clothing at rest periods, change shirts
42	FLUIDS Pre-hydration extremely important, if begin dehydrated, will finish worse. Pre-activity weight should be about the same day to day. Monitor urine color and volume. Consume 17-20 oz 2-3 hours prior to activity Consume 7-10 oz 10-20 minutes prior to activity Consume 7-10 oz every 10-20 minutes of activity Post-activity hydration in 2hours NATA Position Statement: Fluid Replacement for Athletes; J Athl Train; 2000;35(2):212-224
43	FLUIDS Fluids should: Be cool- 50-59 F Contain carbohydrate = <8% , no fructose Contain electrolytes- the more the better Palatable - increases intake by 15% Avoid: Caffeine Alcohol Carbonated beverages
44	PREVENTION Other Cooling Measures Fans = convection, evaporation Cool-Mist Fans = convection, lower ambient temperature, wet athlete is not good Air Conditioners = convection, evaporation Cooled Benches = conduction
45	TMS Conductive heat loss through shoulder pads and pressure-cooled water.
46	RISK FACTORS Dehydration: Illness- vomiting, diarrhea Medications- diuretics, caffeine Alcohol Barriers to evaporation: rubber suits, helmets Illness - fever Previous heat illness Obesity: increased BMI = decreased surface area, increased metabolic heat production
47	RISK FACTORS High WBGT the day before Poor physical conditioning Excessive or dark colored clothing Overzealousness Lack of acclimatization Medications- antihistamines, anticholinergics, theophylline Supplements - Ephedra, Recreational drugs - cocaine, LSD, PCP Electrolyte imbalance
48	RISK FACTORS Medical conditions: Malignant Hyperthermia Neuroleptic Malignant Syndrome ASCVD Scleroderma Cystic Fibrosis Sickle Cell Trait Children Older athletes Spinal cord injuries
49	THE END