Exercise-Associated Hyponatremia, Hyperthermia, and the Balance of Fluids

1. Exercise-Associated Hyponatremia, Hyperthermia, and the Balance of Fluids Andrew Getzin, MD Clinical Director Cayuga Medical Center Sports Medicine and Athletic Performance www.cayugamed.org/sportsmedicine

2. Understand how to diagnose and treat exercise-associated hyponatremia Understand the best means for lowering core body temperature in a hyperthermic athlete Gain an improved understanding of individual fluid needs for endurance athletes Objectives

3. Administering NS at 200cc/hour for 24 hours Hypertonic (3%) saline intravenous 100mL bolus Wait for the individual to void Lasix 80mg Question 1: What is the correct treatment for minimally symptomatic exercise-induced hyponatremia?

4. Cooling fans Ice water immersion at 2°C Warm water immersion at 26°C Eating lots of ice cream Question 2: What is the best way to lower core body temperature in a athlete with heat stroke?

5. He should not consume any fluids 200ml per hour 600ml per hour 1L per hour Question 3: What is the ideal fluid consumption rate for a heat acclimatized 77Kg male competing in an international distance triathlon who is an above average sweater on a 61 degree day with 87% humidity and minimal wind?

6. “I am of the opinion that in the healthy subject the only potential risk to life is heat stroke… a danger well exhibited by examples I have seen of alarming collapse and, on one occasion, death.” Sir Adolphe Abrahams, article on athletics, Encyclopaedia of Medical Practice, 1950

7. Sawka, MSSE 1992

8. Hypohydration Effects on Aerobic Power Sawka, MSSE 1992

9. Wyndham and Strydom, 1969, SA Medical Journal Sugar’s marathon x 2 in 1968 20 volunteers Increase rectal temperatures when 3% water deficit The Danger of an Inadequate Water Intake in Marathon Running

12. “The ideal regimen of water drinking is to take about 300ml every 20 minutes or so. This should start right at the beginning of the race.”

13. Drink adequate fluids 24 hours before the event Drink 500ml of fluids 2 hours before exercise During exercise, athletes should start drinking early and at regular intervals in an attempt to consume fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 1996 ACSM Position Stand: Exercise and Fluid Replacement

14. When you are training alone be sure to either carry fluids, stash them along your route or plan to run routes that will take you by places where you can stop at regular intervals for a drink. At group training sessions all runners must stop and drink at every water stop! It is essential that you drink plenty of fluids to stay well hydrated. Thirst is a sign that you’re already dehydrated. Drink before you get thirsty! Team in Training Newsletter 2010

16. Exercise Associated Hyponatremia (EAH) EAH is the occurrence of hyponatremia during or up to 24 hours after prolonged physical activity and is defined by a serum or plasma sodium concentration below the normal reference range of the laboratory performing the test. For most laboratories, this is a [Na+] < 135 mmol/L

17. EAH is primarily a dilutional hyponatremia caused by an increase in total body water relative to the amount of total exchangeable Na+

18. The primary etiological factor in most cases appears to be the consumption of fluids in excess of body fluid losses

19. In most reported cases of symptomatic EAH there is bodyweight gain suggestive of an absolute increase in total body water Body weight loss is expected due to oxidation of substrate A dilutational hyponatremia may still occur with loss of body weight- Lebus CJSM 2010 Weight Gain with EAH

20. Arginine Vasopressin (AVP)

22. plasma AVP (pg/ml) plasma Osmolality 296 294 292 290 288 286 284 282 280 278 9 8 urine osmolality (mOsm/kg H2O) maximal urine excretion rate (ml/h) thirst osmotic threshold 7 6 5 4 250 3 500 1000 2 1 AVP osmotic threshold 0 Verbalis JG, Best Practice and Research Clin Endocrinology and Metabolism 2003

23. Endocrine factors, Hew-Butler Nausea and Vomiting, Rowe Hypoglycemia, Verbalis Cytokines, Siegel Elevated body temperature, Takamata Potential Non-Osmotic Stimuli of AVP During Exercise Hew-Butler, 2010 Br J Sports Med

24. 13% of marathon runners, Almond NEJM 2005 27% of Ironman triathletes, Speedy Clin J Sport Med 1997 5% of cyclists in a 109-km cycle race, Hew-Butler, Br J Sports Med 2010 Which Athletes Have Inappropriate AVP Release?

25. Athlete Related Risk Factors for EAH Excessive drinking Weight gain Low body weight Female sex Slow running Event inexperience NSAIDs Hew, Clin J Sports Med 2003

26. Event Related Risk Factors for EAH • High fluid availability • > 4 hours of exercise • Unusually hot conditions • Extreme cold

27. Sodium Loss and EAH Excessive sodium loss has not yet been demonstrated to be a causative factor in the pathogenesis of EAH Sodium loss has been shown to be no greater in individuals who develop EAH than in individuals who do not

28. All drinks have sodium concentration of <125 mmol/L The ingestion of sodium will be excreted in the urine rather than retained in the body of inappropriate AVP is released Ingestion of Electrolyte Drinks Can Not Prevent EAH

29. EAH Early Signs and Symptoms Bloating Puffiness Headache Nausea/Vomiting Statement of 2nd International EAH Conference, New Zealand 2007. Clin J Sports Med 2008

30. EAH Late Signs and Symptoms Altered mental status Seizures Respiratory distress Coma Death

31. Hyponatremia Post Treatment Ayus, Ann Intern Med 2000

32. Treatment of Minimally Symptomatic EAH Restrict fluid intake until the onset of urination Seek medical attention if symptoms worsen IV isotonic or hypertonic fluid administration is not usually necessary

33. Treatment of Severely Symptomatic EAH Administer a bolus infusion of 100ml 3% NaCl Up to 2 additional boluses of 100ml of 3% NaCl may be given at 10 minute intervals if no clinical improvement This regimen should not pose any substantial danger to the patient Stabilize, transport immediately, communicate with ER Hew Butler, Clin J Sport Med 2008

34. Symptomatic EAH Treatment Avoid the administration of isotonic or hypotonic fluids to prevent worsening the degree of hyponatremia and fluid overload

36. Chicago Marathon 2007 • October 2007, 31° C (88°F) • 35 year old male police officer died from heat stroke • 300 hospitalizations • Canceled the marathon half way into it

37. Mechanism of Heat Transfer • Conduction: transfer of heat from warmer to cooler objects • Direct Contact • Water 32x > air • Convection: movement of heat away from body by the movement of ambient air • Radiation: heat transfer by electromagnetic waves • Evaporation: conversion of liquid to gas • Greatest means of cooling when running • For every 1.7 ml of sweat evaporated, 1kcal of heat is dissipated

38. Thermoregulation with Heat Stress Metabolic Heat Load (Exercise) Environmental Heat Load Body heat Core temperature Sweating Cutaneous vasodilatation Heat loss by radiation from skin surface Heat loss by evaporation

39. Increase aerobic capacity Increased number of mitochondria/cell Increased muscle glycogen stores Training at intensity of 50% VO2max provides for ½ acclimatization needs Increased sweating capacity Lower temperature threshold for vasodilation Increased volume Increased Aldosterone production 10-25% increase in plasma volume Lower sweat sodium concentration Acclimatization

40. Spectrum of Heat Illness • Heat cramps • Heat edema • Heat exhaustion • Heat stroke

41. Dehydration, electrolyte loss, core temperature normal or slightly elevated Symptoms: orthostatic vital signs, dyspnea, weakness, profuse sweating, nausea/vomiting, irritability, headache, absence of serious central nervous system dysfunction Treatment: moderate cooling, remove to cool environment, remove excess clothing, fans, cool water, IV fluid if necessary Commonly occurs Heat Exhaustion

42. Core temperature>40°C (104°F) + CNS dysfunction Symptoms: hypotension, vomiting, diarrhea, mental status change, seizures, coma Lab abnormalities: increased LFTs, increased CPK, proteinurea, granular casts, hematuria, myoglobinuria Poor prognosis: temp >42°C (107.6), aspartate transaminase >1000 first 24 hours Heat Stroke

43. Heat Stroke - Multisystem Sequelae Ambient temp Prolonged sweating Anticholinergic meds Seizures Exercise K+ Vasodilatation Fluid losses Muscular hyperactivity Muscle perfusion Shock Sweating ceases Rhabdo myolysis Acidosis Further core temp Myoglo- binuria K+ DIC Acute renal failure Arrhythmias Myocardial injury CNS damage

44. Heat Stroke Diagnosis • Valid temperature: ideally core temperature via rectal • CNS dysfunction: coma, altered consciousness, irrational behavior, confusion, convulsions, disorientation, irritability, apathy, hysteria

45. Treatment Lawrence, et al, Exertional Heat Illness During Training and Competition, MSSE 2007

46. Water Immersion • Have tub prepared in advance • Temperature between 2°C (35.6°F) and 26°C (78.8°F)? • Pull out at about 38° (100.4°F) • Monitor athlete closely • Transport second Proulx, et al, J Appl Phys 2002

47. Hyperthermia Prevention

48. What Is the Correct Amount Of Fluid? Dehydration increases the risk for hyperthermia. Overhydration can cause EAH. It is OK to drink as thirst dictates. Approximately 400-800ml (1 large water bottle) per hour Less fluid for slower, smaller athletes exercising in mild environment Be conditioned to environment. Practice drinking in your training. LISTEN TO YOUR BODY!!! Noakes, IMMDA-AIMS Advisory statement on guidelines for fluid replacement during marathon running, Clin J Sports Med 2003

49. Prevention Drink to thirst Monitor body weight If you feel your temperature rising, slow down!

50. If they make it to the finish line- statistics are positive What is the temperature? What is the distance of the race? Who are you evaluating? Exam including a rectal temp, ?sodium level Hyperthermia vs. Hyponatremia