PREDISPOSING RISK FACTORS FOR HEAT ILLNESS AND STROKE

EXERTIONAL HEAT STROKE

LESSONS LEARNED FROM FATAL EPISODES OF HEAT STROKE

Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19, 2009(GETAC – Governor’s EMS & Trauma Advisory Council, Texas Department of State Health Services)

There are no new lessons to be learned about heat stroke, only new athletes, coaches, trainers, and parents to educate. There are no new events, just the same well-known circumstances that are repeated every year with new, unwary victims. At least 21 young athletes have died from heat stroke during the last several years. (30, 31)

The deaths of Korey Stringer, the Minnesota Viking’s Pro Bowl offensive lineman, on August 1, 2001 and Eraste Autin, the University of Florida’s freshman who collapsed July 19, 2001 after a summer training session and spent six days in a coma before dying, are only two of many widely publicized examples of tragic, but preventable, deaths. We may also recall Matthew Thomas, the 14 year old Victoria Texas High School freshman, who succumbed shortly after football practice during a 92-degree afternoon on August 12, 2003, 17 year old Chris Stewart from Oklahoma City who died of heat stroke in August 2005, (21-28) and Max Gilpin, a 15 year-old Louisville, Kentucky player who collapsed and died when his temperature rose to 107 degrees following a series of wind sprints called “gassers” on a 94 degree day in August 2008. (48, 49, 50, 51, 52, 53)

The typical heat stroke victim is usually not well-acclimatized to the Texas heat. It should be no surprise that student athletes who have spent the summer watching TV and playing video games in the comfort of their air-conditioned homes may not be physically prepared for exertion in the heat. (6, 17)

Overall, however, student athletes are extremely motivated, perhaps sometimes even overzealous, individuals who may push themselves beyond their level of endurance and heat tolerance in their attempt to excel in their sport. (17,19,32,43) During team try-outs an athlete may feel pressured to perform beyond his capability in the heat, ignoring signs and symptoms of impending heat-related illness.

When the brain signals that something was wrong, the athlete can override his brain and keep exerting himself. A competitive athlete is not going to voluntarily take himself out of the competition, an action which might jeopardize his place on the team. Disregarding his brain’s signals, the athlete consciously continues to participate beyond the threshold of safety. His brain even starts to fail, manifested by confusion and atypical behavior, as he generates more body heat than he can possibly lose. His body simply overheats.

The human body has a thermal regulation system that strives to maintain temperature at 98.6 degrees Fahrenheit. That temperature is the comfort zone in which all human biological systems operate efficiently. (46) The body dissipates heat with radiation, conduction, convection, and from the evaporation of sweat. (2, 43, 46) Radiation transfers heat energy via infra-red waves from a hotter to a cooler source, like the glow from a red-hot branding iron as skin capillaries dilate to increase blood flow causing the skin to become red and hot. Heat transfer through conduction occurs through direct contact with an object such as heat gain by touching a hot surface or heat loss by direct contact with ice packs or cold water immersion.

Convection occurs when a cool breeze flows over the hot surface causing heat loss into the ambient air much like heat leaving the cooling plates of a car radiator.

Finally, the evaporation of sweat also causes heat loss as liquid water turns into water vapor. The cooling effect of sweating islessened by high humidity that prevents evaporation. Sweating is also decreased by dehydration from insufficient water intake, normal respiratory water loss, and fluid losses from vomiting. When fluid losses are great, the body starts to lose intravascular volume—the volume of fluid in arteries and veins. (45)

The pulse rate increases as the heart tries to maintain circulation and an adequate blood pressure. To avoid going into shock, the body closes capillaries to direct blood flow away from the skin, gut, and muscles to more vital organs, such as the brain, kidneys, and liver. (44) When the skin capillaries close, the blood leaves the skin surface. Sweating may stop. The skin becomes cool and clammy and goose bumps may appear. (17, 18, 46) The shunting of blood from the skin is what causes people to feel chilled when going into shock. Vomiting and muscle cramps may occur. (7, 38) The failure of the body’s cooling mechanisms—the radiator effect and the sweating-evaporation process—causes an internal heat surge.

Excessive accumulation of heat energy causes thermal injury to biological systems including breakdown of muscle tissue, rhabdomyolysis, potentially irreversible multi-organ failure, and sometimes death. (2, 8, 9, 12, 16, 17, 32, 43, 46)

Early symptoms of heat injury include: thirst, dizziness, lightheadedness, paleness, headache, poor concentration, missed assignments, irritability, altercations, apathy, weakness, fatigue, and a feeling of being limp. More advanced symptoms include: warm and flushed (red) skin, muscle cramping, nausea, and vomiting.

Emergency symptoms of impending heat stroke include: the appearance of cool and clammy skin, absence of sweating, dry skin, rapid breathing, confusion, a change in personality often perceived as “goofing off” and not following instructions, fainting, and eventual collapse. (2,3,11,12,13,14,17,20,31,43)

Treatment must include immediate rapid cooling in the field with ice packs and cold water, with total body immersion if possible. Restrictive clothing should be removed. Every minute of exposure at high core temperatures causes more tissue damage. Every minute counts in a “heat” attack, much like a heart attack. (31)

Emergency hospital care is needed for anyone who collapses during heat-related exertion, and rapid cooling should begin in the field and continued during transport to the hospital. (1,12,17,31,32,33,43)

Prevention strategies are the main approach to reducing the risk of exertional heat stroke. The following measures are recommended.

1. Gradually acclimatize participants to heat with light work-outs the first week of practice. Most heat strokes occur during the initial few days of practice when athletes are not acclimatized to the exercise intensity and equipment. (9,17,18,31,32,43,46)

2. Provide free, unlimited, unquestioned access to cool, palatable water. (5,19,30,31,43)

3. If a player is thirsty he is already dehydrated. He must be allowed to drink without having to ask permission. Drinking 8 ounces of a balanced electrolyte solution such as found in sports drinks every 15 minutes, up to a liter per hour, is recommended before a player feels thirsty. A single swallow from a squirt bottle is not sufficient fluid replacement. (9,11,12,13,16,31,43)

4. Weigh players before and after practice to verify proper fluid replacement. If players lose weight during practice, they are dehydrated and at risk of compromising one of their chief means of cooling — sweating. (17,20,43,46)

5. Take mandatory breaks in the shade and allow players to remove helmets. (31,43)

6. Bathroom facilities should be available, as their absence may discourage adequate oral hydration by players who may feel embarrassed if they need to urinate
.
7. Although water and balanced electrolyte solutions are helpful, salt tablets are not recommended. (10,11,12,13,14,29) Like drinking seawater, taking salt pills can be harmful. In order to eliminate excess salt the body loses water, water it can not afford to lose during conditions of over-heating. (46,47)

8. Good hydration alone does not prevent heat stroke! Even if one drinks plenty of water and sports drinks and is making lots of dilute urine (a sign of good hydration), heat stroke can still occur if the body generates or absorbs more heat that it can dissipate by its usual cooling mechanisms. (16,17,19,43,46)

9. Exposure to direct sunlight increases the radiant energy absorbed as heat. Test this phenomenon by placing a hand on the hood of a car parked in direct sunlight compared with a car parked in the shade. The air temperature is the same, but the vehicle in the sun is much hotter than the one in the shade. If a practice is held in direct sunlight, the heat index increases by up to 15 degrees F, and those 15 degrees should be added to the heat index given by the National Weather Service to determine the risk of heat-related injury. (2,37)

10. Do not allow any outdoor activity if the heat index is 130 or greater. (37)

11. The above guidelines may vary with the age, weight, and conditioning of individual players. To be on the safe side, in his newspaper column “To Your Good Health” Dr. Paul Donohue recommends suspension of practice if the heat index is 90 or greater (Exertional Heat Stroke, a Preventable Cause of Death, Victoria Advocate, July 14, 2007, page E-5). (35)

12. Monitor players for symptoms of heat exhaustion. (1) A player is unlikely to admit that he is feeling weak or lightheaded. He is unlikely to pull himself out of the practice. A buddy system, like one used by scuba divers, may help one player protect and monitor another. (17,18,31,32,37)

13. If a player is dizzy, lightheaded, not “feeling right” or vomits, he must stop practice immediately and be allowed to cool off in the shade with ice packs and soaked towels, or with a cool water mist and fan, with his uniform removed. Vomiting should prohibit anymore practice that day. Notify the parents so the player is monitored at home and properly fed and rehydrated. (12,13,14,17,31)

14. If a player collapses, or if exertional heat stroke is suspected, a player should be rapidly cooled by immediately removing all equipment and uniforms and immersing him cooled in a tub of ice water until EMS can assume care and transport to the hospital.

It is important to cool first, transfer second. Every minute spent above a body core temperature of 104 degrees F, measured rectally or with an esophageal probe, worsens the tissue damage and increases the risk of death. (2,12,13,14,17,19,20,31,32,43,46) Oral, tympanic membrane, and temporal artery temperatures do not accurately measure core temperatures in this setting. (17,43)

15. Avoid stimulants such as highly caffeinated “energy-boosting” drinks (which have fluid-losing diuretic effects), ephedra, ephedrine, amphetamines, and cocaine, which can cause cardiac rhythm disturbances. (2,12,17,32)

16. Practice during the cooler parts of the day, when the heat index is lowest, preferably less than 90, although practice with a heat index of less than 105 may be more practical and acceptable, with appropriate precautions. (17,43)

17. Do not gauge the intensity of practice by pushing players until they get cramps, vomit, or collapse. Remember that if a player is having one symptom, more are likely to follow, possibly in a rapid cascade of downhill events. (32,46)

18. Heat stroke has occurred in marathon runners in relatively cool temperatures of 60 degrees! (32,33,43) The fundamental principle causing exertional heat injury is the generation of heat faster than the heat can be lost. The result is a harmful rise in body core temperature. A core (rectal) temperature of 104 is very dangerous; at 108 the person is likely to die. (1,2,12,16,17,31,38,43,46)

19. The sickle-cell trait, present in 8% of the black population and also found in people of Mediterranean descent, can pre-dispose an athlete to a sickle-cell crisis during times of heat-related stress. A high index of suspicion is necessary when such participants demonstrate any sign or symptom of illness, such as muscle cramps or abdominal pain. Treatment with immediate intravenous hydration and supplemental oxygen may be life-saving and may prevent damage to vital organs.
(1,15,17,40,41,42,43)

20. Players who are ill with fever, diarrhea, vomiting, or viral illnesses should refrain from exertion in the heat. (17,19,32,43)

21. Create a team effort to prevent dehydration and heat stroke involving the coaches, trainers, administrators, parents, and athletes. (31)

22. Remember that poor concentration, missed assignments, frequent penalties, irritability, altercations on the field, muscle cramps, loss of liveliness and spirit, apathy, and increasing frustration of the players and coaches in the fourth quarter may be prevented by what is done in the first quarter regarding proper fluid and electrolyte replacement. A player’s poor performance may not be due to lack of desire or not wanting “it” enough. Sub-par performance may simply be due to a lack of water and over-heating! (16,19,31,43) Like continuing to drive a car with a dry radiator, engine failure is likely to occur.

23. Consider posting an educational heat stroke poster in the locker room. (39)

24. Refer to the accompanying temperature/humidity chart to determine the heat index, or use the programs on www.zunis.org to determine the wet bulb globe temperature and follow the football guidelines and recommended precautions. (37)

For example, the National Weather Service uses the Steadman Heat Index on the following page to provide hot weather advisories to the general public. Using the table, an air temperature of 90 with a relative humidity of 60% produces a Heat Index of 100. This heat index is associated with a low risk of heat-related illness, but appropriate precautions should be taken because heat injury can still occur. If players are exposed to direct sunlight, however, the heat index in the same conditions rises to 115 degree F, a danger zone for exertional heat injury. (,37)

During practice the coach should ask this question: “Are my players being exposed to direct sunlight casting shadows shorter than their height?” If the answer is “Yes” then add 15 degrees to the heat index chart and take appropriate precautions, such as practicing early in the morning, late in the evening, or inside a gym. (2,37,43)

A heat index of 105 and greater represents a danger zone, and heavy exertion should be avoided. In addition, mandatory breaks in the shade with helmets off and mandatory consumption of 8 ounces of water or a sports drink every 15 minutes should be the rule. A few swallows from a squirt bottle are not sufficient to maintain adequate hydration. Because the judgment of the athlete may be impaired in this setting, the player is unlikely to pull himself out of training exercises.

Therefore, trainers and coaches should be observant, monitor their athletes for any symptoms of heat-related illness, and insist that players be removed and protected from dangerous environmental conditions. Prevention and treatment strategies must be in place. (4,5,17,19,43) Remember the advice of experts: “the cooler you stay, the better you play.” (17,18,19)

Note: Exposure to full sunshine can increase HI values by up to 15° F
Alternatively, add 5° F to the temperature when athletes are exposed to direct sunlight

Green Highlighted Heat Index: 90—104. When the heat index is between 90° F and 104° F, heat exhaustion and heat cramps are possible with prolonged exposure and physical activity. Ad lib access to cool water is necessary. Mandatory breaks in the shade every 20 to 30 minutes and extra fluids (water and/or sports drinks) are recommended. Ice water and cold, wet towels for rapid cooling in the shade should be immediately available. Cooling water mist fans are desirable. Observe players carefully!

Yellow Highlighted Heat Index: 105—129. Practice is dangerous in this setting. Under these conditions, instructional “walk-through” drills with minimal running and no contact should be considered. Ad lib access to cool water is necessary. Mandatory breaks in the shade every 15 to 20 minutes and extra fluids (water and/or sports drinks) are needed. An ice water tub for total body immersion or cold, wet towels for rapid cooling in the shade should be immediately available. Cooling mist fans are helpful.

Red Highlighted Heat Index: 130 and Higher. Outdoor exposure and any type of outdoor practice should be prohibited, as heat stroke risk is very great at this level of humidity and temperature. The body’s ability to cool by convection and evaporation of perspiration is severely impaired. In fact, in this environment the body will passively absorb heat from the ambient air and direct sunlight, and cooling by the sweating-evaporation mechanism is not possible because evaporation does not readily occur. Any exertion under these circumstances produces a high risk for exertional heat stroke.

Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19, 2009

Heat Stroke References

1. Vertuno Jim, The Associated Press, Longhorns Tackling the Heat: Pill Helping Texas Survive Rising Temperatures, published by the Victoria Advocate, August 15, 2007.
2. Hyperthermia, Wikipedia Encylopedia, October 2006, Retrieved from “http://en.wikipedia.org/wiki/Hyperthermia”
3. Heat Illness, Heat Exhaustion, Heat Stroke. The Nemours Foundation/Kids Health at www.revolutionhealth.com January 3, 2007.
4. Joseph Rampulla, MS,APRN,BC (June 2004). Hyperthermia & Heat Stroke: Heat-Related Conditions (pdf). The Health Care of Homeless Persons pp.199-204. Boston Health Care for the Homeless Program. Retrieved on 2007-02-22 at: http://www.bhchp.org/BHCHP%20manual/pdf_files/part2_PDF/Hyperthermia.pdf .
5. “Are you ready for extreme heat?” Courtesy: Federal Emergency Management Agency, Department of Homeland Security. Available from FEMA at: www.fema.gov/areyouready/heat.shtm. Updated August 20, 2007. This information may have changed or been updated since it was accessed. For the most current information, contact FEMA at http://www.fema.gov/.
6. Scott Anderson “Preventing Muscle Cramping in Football”. Coach and Athletic Director. May 2001. At www.FindArticles.com, 15 September 2007. http://findarticles.com/p/articles/mi_m0FIH/is_10_70/ai_n18611880 E.
7. Randy Eichner “Muscle cramps: the right ways for the dog days”. Coach and Athletic Director. August 2002. FindArticles.com. 15 Sep. 2007. http://findarticles.com/p/articles/mi_m0FIH/is_1_72/ai_n18613963.
8. Maddali Sirish, Rodeo Scott, Barnes Ronnie, Warren Russell, Murrell George: Post-exercise Increase in Nitric Oxide in Football Players with Muscle Cramps. The American Journal of Sports Medicine 26: 820-824, 1998.
9. Ruiz E J, Mitchell I D, Eberman L E, Cleary M A. Severe dehydration with cramping resulting in exertional rhabdomyolysis in a high school quarterback. In Cleary M A, Eberman LE, Odai ML eds. Proceedings of the Fifth Annual College of Education Research Conference: Section on Allied Health Professions. April 2006; 1: 31-35. Miami: Florida International Univeristy. http://coeweb.fiu.edu/research_conference/.
10. Cleveland Minot. Musle Cramp. University of Illinois Medical Center at Chicago: Health Library, at www.uimc.discoveryhospital.com, March 13, 2000; reviewed January 4, 2007. “Salt tablets are not useful and should be avoided.”
11. Texas Children’s Hospital. Preventing Heat Illness. Texas Children’s Hospital: Caring for Your Child’s Health at www.texaschildrenshospital.org, 2005. “Salt pills are unnecessary and possibly dangerous.”
12. Centers for Disease Control and Prevention. Frequently Asked Questions about Extreme Heat. Emergency Preparedness and Response Website at www.bt.cdc.gov/disasters/extremeheat/faq.asp. August 15, 2006. “Do not take salt tablets unless directed by your doctor.”
13. Gillis Rick (reviewer). Heat-Related Illness Can Quickly Become Serious. Healthlink: Medical College of Wisconsin at:
Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19, 2009 www.healthlink.mcw.edu/article/1031002770.html, June 28, 2007. “Salt pills should not be used without first asking your health care provider.”
14. Taylor-Oring Leslie. Is it Heat Exhaustion or Heat Stroke? Tae Park Tae Kwon Do at: www.eod.gvsu.edu/tkd/newpage22.htm. March 14, 1999. “Give them cool liquids—NO SALT PILLS.”
15. Eichner Randy. Curbing Muscle Cramps: More than Oranges and Bananas. Hot Topics in Sports Nutrition. Gatorade Sports Science Institute, at: www.gssiweb.com/ShowArticle.aspx?articled=619. July 25, 2003.
16. Coyle Edward. Fluid and Carbohydrate Replacement During Exercise: How Much and Why? Gatorade Sports Science Institute, Sports Science Exhange #50, Volume7 (1994), Number 3, at: www.gssiweb.com/Article_Detail.aspx/articleid=23&level=2&topic=2.
17. Eichner Randy. Heat Stroke in Sports: Causes, Prevention, and Treatment. Gatorade Sports Science Institute, Sports Science Exchange #86, Volume 15 (2002), Number 3, at: www.gssiweb.com/Article_Detail.aspx?articleid=597&level=2&topic=7.
18. Eichner Randy. Heat Stroke in Sports: How to Protect Yourself and Help Your Teammates. Gatorade Sports Science Institute, Sports Science Exchange #86, Volume 15 (2002), Number 3 Supplement, at: www.gssiweb.com/Article_Detail.aspx?articleid=597&level=2&topic=7.
19. Murray Robert, Eichner Randy. Preventing Heat Illness: Keeping Athletes from Falling into Danger Zones. Gatorade Sports Science Institute, Sports Science Library at: http://gssiweb.com/Article_Detail.aspx?articleid=570&level=2&topic=7.
20. Casa Douglas, Murray Robert. Sports Science News: Preventing Exertional Heat Illness: A Consensus Statement. Gatorade Sports Science Institute, Sports Science Library, 2007, at: http://gssiweb.com/Article_Detail.aspx?articleid=625&level=2&topic=7.
21. Conrad Mark. Mark’s View: Heat Stroke and Football Practice (A comment on the heat stroke death of Minnesota Viking Korey Stringer). Mark’s Sportslaw News, 2001, at: www.sportslawnews.com.
22. CNN News. Vikings football player dies of heat stroke, at: www.CNN.com./U.S., August 1, 2001. This is a CNN news story about Korey Stringer.
23. Associated Press, Mankato, Minnesota. Vikings tackle Stringer dies from heatstroke, August 2001.
24. The Associated Press, Gainesville, Florida: Florida player Autin dies six days after heat stroke. Volume 101, No. 187, Thursday, July 26, 2001. This article discusses the heat stroke death of 18 year old freshman Eraste Autin who collapsed during a work out in 88 degrees, 72% humidity, heat index of 100.
25. Smith Michael. Football Practice Heat Stroke Deaths Preventable (An article about the heat stroke death of 18 year old Chris Stewart). MedPage Today, Daily Headlines, Oklahoma City, August 18, 2005.
26. Sparks Tara. Death has parents concerned. Victoria Advocate, page 1, August 15, 2003 at: www.nl.newsbank.com/nl-search/we/Archives?p_product=VA&P_t.
Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19, 2009 This article describes a parents’ safety meeting following the death of 14 year-old Matthew Thomas.
27. Victoria Advocate staff writer. Autopsy not yet released. Victoria Advocate, page 1, August 15, 2003, at: www.nl.newsbank.com/nl-search/we/Archives?p_product=VA&P_t.
28. deLench Brook. To Nineteen Youth Athletes Dying Young. MomsTeam, A Parents Trusted Youth Sports Source, at www.momsteam.com. August 25, 2007.
29. Reddy Vinay. Heat Cramps, Heat Exhaustion, and Heat Stroke. Dr. Reddy’s Pediatric Office on the Web at http://www.drreddy.com, 1/12/07.
30. Williamson David. UNC Warns of Possible Heat Strokes for High School Atheletes, at www.unc.edu//depts/nccsi, 2004.
31. Roberts William. Death in the Heat: Can Football Heat Stroke be Prevented? Current Sports Medicine Reports. (3), 2004.
32. Roberts William. Common Threads in a Random Tapestry: Another Viewpoint on Exertional Heatstroke, The Physician and Sports Medicine. 33(10) 2-5, October 2005.
33. Roberts William. Exertional Heat Stroke during a Cool Weather Marathon: A Case Study. Medicine & Science in Sports & Exercise, Official Journal of the American College of Sports Medicine, pages 1197-1203, January 2006 at http://www.acsm-msse.org.
34. Fighting Heat Stress, at http://fighting_heat_stress,asp.htm.
35. Donohue Paul. Exertional Heat Stroke: A Preventable Cause of Death, To Your Good Health. Victoria Advocate, page E-5, Saturday, July 14, 2007.
36. Jung Alan, Bishop Phillip, Al-Nawwas Ali, Dale Barry. Influence of Hydration and Electolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps. Journal of Athletic Training 40(2): 71-75, April-June 2005.
37. The Zunis Foundation. How Hot is Hot? How Safe if Safe? At www.zunis.org, April 8, 2007.
38. It’s Hot, It’s Humid, It’s Sunny: Information on Heat and Sun-Related Illnesses. Street Medics, www.action-medical.net
39. Hirsch Larissa. Heat Exhaustion and Heat Stroke: A Poster. This is a handy instructional “Heat Sheet” found at www.kidshealth.com
40. Bergeron Michael F, Cannon Joseph G, Hall Elaina L, Kutlar Abdullah. Erythrocyte Sickling During Exercise and Thermal Stress. Clinical Journal of Sport Medicine. 14(6): 354-356, November 2004.
41. Gallais Daniel Le, Bile Alphonse, Mercier Jacques, Paschel Marc, Tonellot Jean Louis, Dauverchain Jean. Exercise-induced death in sickle cell trait: role of aging, training, and deconditioning. Medicine and Science in Sports and Exercise. 28(5): 541-544, May 1996.
42. Kark J A, Posey D M, Schumacher H R, Ruehle C J. Sickle-cell trait as a risk factor for sudden death in physical training. New England Journal of Medicine. (317): 781-787, September 1987.
43. Binkley Helen M, Beckett Joseph, Casa Douglas J, Kleiner Douglas M, Plummer Paul E. National Athletic Trainers’ Association Position Statement: Exertional
Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19,
2009
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Heat Illnesses. Journal of Athletic Training. 37(3): 329-343, July-September 2002.
44. Guyton Arthur C, Hall John E. Circulatory Shock and Physiology of its Treatment, Chapter 24, Textbook of Medical Physiology, Eleventh Edition. W.B. Saunders Company, Philadelphia, June 2005.
45. Guyton Arthur C, Hall John E. The Body Fluid Compartments: Extracellular and Intracellular Fluids, Chapter 25, Textbook of Medical Physiology, Eleventh Edition. W.B. Saunders Company, Philadelphia, June 2005.
46. Guyton Arthur C, Hall John E. Body Temperature, Temperature Regulation, and Fever, Chapter 73, Textbook of Medical Physiology, Eleventh Edition. W.B. Saunders Company, Philadelphia, June 2005.
47. Guyton Arthur C, Hall John E. Regulation of Extracellular Fluid Osmolarity and Sodium Concentration, Chapter 28, Textbook of Medical Physiology, Eleventh Edition. W.B. Saunders Company, Philadelphia, June 2005.
48. Graves, Will. Case of Kentucky Coach puts Football on Trial. The Associated Press. The Victoria Advocate, page C-7, Friday, January 30, 2009.
49. Mahalo.com. Max Gilpin, at http://www.mahalo.com/max-gilpin
50. Louisville News, Homepage. Witness: Teen’s Death was Preventable. August 27, 2008. http://www.wlky.com/news/17315849/detail.html Copyright 2008 by WLKY.com.
51. Konz, Antoinette. 911 Call: PRP player drifted in, out of consiousness. Courier-Journal.com, Louisville, Kentucky at http://www.courier-journal.com/article/20081107/NEWS01/811070437/1008/rss01, November 7, 2008.
52. WLKY.com. PRP Football Player Collapses at Practice, In Critical Condition. http://www.wlky.com/sports/17267086/detail.html. August 22, 2008.
53. WLKY.com. PRP Football Player Dies 3 Days after Collapse in Practice. Louisville, Kentucky. At http://www.wlky.com/health/17280899/detail.html, August 27, 2009.
54. Binkley, Helen; Beckett, Joseph;Casa, Douglas; Kleiner, Douglas; Plummer, Paul. National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses. Journal of Athletic Training. 2002 Jul-Sep; 37(3): 329-343.
55. Parents’ and Coasches’ Guide to Dehydration and other Heat Illnesses in Children. National Safe Kids Campaign. Adapted from: Inter-Association task force on exertional heat illnesses consensus statement: National Athletic Trainers’ Association. June 2003. Available at: www.nata.org/industryresources/heatillnessconsensusstatement.pdf.
Prepared by Stephen T. Hougen, M.D., F.A.C.S., GETAC Injury Prevention Committee, August 19, 2009

_____________________________________________________________________

How hot is hot enough to cause Heat Illness or Heat Stroke? That is a moving target because Predisposing Factors contribute to Death from Heat Illness or Heat Stroke and abnormal body heat balance.

There are reports of death from heat illness with temperatures in the 70″s. because of these Predisposing Factors. Temperature alone from dehydration from insufficient water consumption might not be the sole cause of heat illness.

An Athlete patient can be diagnosed with heat illness if one of the following is associated with body heat imbalance and increased lethal body temperature while working or exercising in the heat.

Water consumption errors do not always account for all heat illness death. Predisposing Factors for heat imbalance and increased body heat and death from heat illness will only be ruled in or out after autopsy.

The following contributing factors: Reference: William O. Roberts, MD, a sports medicine specialist with MinnHealth in White Bear Lake, Minn

I..ENVIONMENTAL

A..Heat Wave
B..Dangerous Heat Index
C..Increased Ground Level Ozone

II. Pathophysiology Predisposing conditions alter heat balance

1. Increased Endogenous Heat load : Vigorous Exercise or overexertion,
2. Increased Exogenous Heat load
a. Sun Exposure
b. Increased Heat Index
c. Dangerous Air Quality. Increased Ground Level Ozone (mbmsrmd)
3. Decreased Heat Dissipation

a. Exogenous cause
i. Humidity
ii. Occlusive or excessive clothing

b. Endogenous cause
i. Dehydration
ii. Lack of acclimatization
iii. Healed burns
iv. Sunburn
v. Dermatitis
vi. Sweat Gland Dysfunction
vii. See Medications Predisposing to Heat Illness

III. Other predisposing factors for abnormal heat balance

a. Prior Heat Stroke

b. Concurrent infection
i. Upper Respiratory Infection
ii. Gastroenteritis

c. Elderly
i. Myocardial dysfunction
ii. Decreased muscle mass
iii. Decreased skin blood supply
iv. Renal insufficiency
v. Chronic illness

d. Comorbid medical condition
i. Anorexia
ii. Cystic Fibrosis
iii. Diabetes Insipidus
iv. Poorly controlled Diabetes Mellitus
v. Obesity
vi. Hypokalemia

IV. MEDICATIONS

A. Sympathomimetic Medications (alpha adrenergic agonists)

1. Amphetamines
2. Epinephrine
3. Ephedrine
4. Cocaine
5. Norepinephrine

B. Anticholinergics
1. Atropine
2. Scopolamine
3. Benztropine mesylate
4. Antihistamines

C. Diuretics
1. Caffeine
2. Alcohol
3. Furosemide (Lasix)
4. Hydrochlorothiazide
5. Bumetanide (Bumex)

D. Phenothiazines
1. Prochlorperazine
2. Chlorpromazine hydrochloride
3. Promethazine hydrochloride

E. Butyrophenones
1. Haloperidol (Haldol)

F. Tricyclic Antidepressant
1. Amitriptyline (Elavil)
2. Imipramine
3. Nortriptyline
4. Protriptyline

G. Monoamine Oxidase Inhibitors
1. Phenelzine
2. Tranylcypromine

H. Recreational and Illicit Drugs
1. Alcohol
2. Lysergic Acid diethylamide (LSD)

I. Other Medications
1. Beta Blockers
2. Calcium Channel Blockers
3. Lithium
4. Heat Illness Prevention

References
Czerkawski (1996) Your Patient Fitness 10(4): 13-20
Sandor (1997) Physician SportsMed, 25(6):35-40
Barrow (1998) Am Fam Physician 58(3):749
Hett (1998) Postgrad Med 103(6):107
Wexler (2002) Am Fam Physician 65(11):2307

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