Illnesses related to Heat Stress or Fluid/Electrolyte Imbalances: Are

there Gender Differences?

Sandra Fowkes Godek PhD, ATCDepartment of Sports Medicine

West Chester University

Illnesses related to Heat Stress or Fluid/Electrolyte Imbalances

• Muscle Cramps (exercise related)• Heat Syncope (orthostatic dizziness)• Exercise associated collapse• Heat Exhaustion

– Salt Depletion (hypovolumic Hyponatremia)– Water Depletion*– can lead to Heat Stroke

• Hyponatremia#

• Heat Stroke#

– Classical– Exertional

* Can lead to a medical emergency# Is a medical emergency

Heat Illnesses?

• Hyperthermic Disorders– Water Depletion Heat

Exhaustion• Symptomatic with core

temperature 102 - 104°F

– Heat Stroke• Symptomatic with core

temperature > 104°F

• Electrolyte Disorders– Exertional muscle cramps– Postural hypotension or

Orthostatic Dizziness (heat syncope)

– Hyponatremia (low serum sodium levels)

• Hypervolumic• Euvolumic• Hypovolumic

– Exercise Associated Collapse?

Prevention – General Rules

• Screen athletes for a history of previous heat-related problems

• Be aware of heavy sweaters• Be aware of athletes in poor condition• Monitor athletes on medications (ACE inhibitors,

diuretics)• Educate athletes about supplements (Ephedra)• Monitor urinary indices of dehydration

– Specific gravity (< 1.020 )

Prevention – General Rules

• Fluid Replacement – stay hydrated• Electrolyte replacement – Na+, K+, Mg++• Increase time between two-a-day practices• Monitor environmental conditions

– Alter practices if necessary

• Allow proper time period for acclimatization• Allow for body cooling whenever possible

– Breaks in the shade, ice water towels, cool water showers or wading pools, cool mist fans, air-conditioned areas for resting between practices

Understand that all athletes are not created equal

Gender Differences in Thermoregulation

• Core Temperature– Hormonal influences– Physical size differernces

• Sweat Rates– Hormonal influences– Physical Size differences

Hormonal Influences on Thermoregulation

Muscle Cramps (Exertional)

• Causes– Dehydration? – Not that

simple– May be due to electrolyte

depletion– Some link cramps with low

serum Na+– Some data suggest Mg++

depletion– Others suggest K+ or Ph– Neuromuscular Fatigue

Muscle Cramps - Incidence in Female Athletes

Muscle Cramps – Prevention

• Replace electrolyte losses in sweat.– Rehydrate between practices with

electrolyte drink– Eat foods high in Na+ , K+ and Mg++

• Lunch meats and chips• Soup• Pizza• Whole grain foods• Fruits and Vegetables• Pickles

Muscle Cramps - Recognition

• May be localized to a specific muscle group– Gastroc-soleus– Abdominals– Forearm in throwers

• May be general body cramping– Several muscle groups at the

same time.

Muscle Cramps - Management

• Local muscle cramp– Active inhibition by the

antagonist (reciprocolinihibition)

– Stretching– Ice application– Fluid and electrolyte

replacement– Rest

Muscle Cramps - Management

• Generalized whole body cramping can present as an emergency.– Fluid and electrolyte

replacement• Oral fluids with added

electrolytes (gatorlytes or salt tablets)

• IV saline

– Rest

Heat Syncope

Peripheral vasodilation

Venous Return

Cardiac Output

Cerebral Ischemia

• Orthostatic dizziness caused by– standing after exercise

allowing pooling of blood in the lower extremities.

– Rapidly assuming an upright posture.

• Usually occurs prior to acclimatization

Heat Syncope – Incidence in Female Athletes

Heat Syncope

• Recognition– Fatigue– Dizziness– Tunnel vision– Pale sweaty skin– Fainting– Deyhdration

• Management– Rest in a shaded

area– Elevate legs– Rehydrate

Heat Exhaustion

• Water depletion H.E. – Caused by inadequate replacement of water

losses (dehydration).– Beginning a second bout of exercise

hypohydrated– Untreated it can lead to heat stroke– Involves and elevated core temperature

Heat Exhaustion

• Salt/volume depletion (Hypovolumic hyponatremia)– Caused by low serum Na+ but may not clinically be classified as

hyponatremia or Na+ < 130 mmol/L– Serum Na+ frequently 130 – 135 mmol/L– Usually occurs in athletes who sweat heavily over several

consecutive days– Water loss is replaced but Na+ is not– Does not involve hyperthermia– Athlete is hypovolumic

Hypovolumic Hyponatremia –Incidence in Female Athletes

Hypovolumic Hyponatremia

• Description- ECV contracted and total body sodium depletion– No body water excess– Whole body sodium deficits– Dehydration– ECV contracted

• Occurs via primary sodium losses (sweat, diarrhea, vomiting)

Hypovolumic Hyponatremia

• Pale, clammy skin• Low BP• Tachycardia• Syncope• Normal body temperature• serum Na+ <135 mmol . l-1

• No edema

• Weakness• Fatigue• Severe headache• Muscle aches• Anorexia• Nausea• Vomiting• Diarrhea

** The athlete feels “sick”

Hypovolumic Hyponatremia -Prevention

• Know your athletes who are hypertensive– Be aware of which

athletes are on a low Na++ diet

– Be aware of athletes on ACE inhibitors

– Medication may need to be altered during preseason

Hypovolumic Hyponatremia –Prevention and Management

• Replace electrolyte losses in sweat.– Rehydrate between practices with

electrolyte drink– Consider adding salt to drinks– Salt foods liberally at meals– Eat foods high in Na+ , Cl- and K+

• Lunch meats and chips• Soup• Pizza• Pickles

Hypovolumic Hyponatremia –Prevention and Management

• Rest• Administer electrolyte drink orally• Consider IV fluid replacement (saline)• Monitor vital signs (blood pressure)• Recovery usually within 24 hours

• Educate athletes about replacement of electrolytes (salt food liberally)

Exercise Associated Collapse (EAC)

• May occur in cool environment

EAC – Incidence in Female Athletes

Medical Emergencies related to Hyperthermia or

Fluid/Electrolyte Imbalances

• Water Depletion Heat Exhaustion• Heat Stroke• Acute Exertional Hyponatremia

(Hypervolumic Hyponatremia)

Water Depletion Heat Exhaustion

– Caused by inadequate replacement of water losses (dehydration).

– Untreated it can lead to heat stroke– Involves and elevated core temperature

• Prevention– Stay Hydrated!

Water Depletion Heat Exhaustion –Incidence in Female Athletes

Water Depletion Heat Exhaustion

• Recognition• Initial Signs/Symptoms

– Core Temperature between 101 - 104°F– Intense thirst– Weakness– Fatigue– Anxiety– Restlessness– Onset of CNS impairment

Progression of CNS Manifestations - May lead to Heat Stroke

• Core Temperature 102 -104°F

• Tachycardia• Hyperventilation• Sweating is usually still

present

• Lab assessment will usually show hypernatremia

• Confusion• Disorientation• Impaired judgement• Paresthesia• Muscle

incoordination

Water Depletion Heat Exhaustion - Management

• Remove clothing and equipment• Cool with cold water immersion, ice towels,

ice bags, shower• Rehydrate with hypotonic fluids• Monitor vital signs (rectal temperature)• Consider IV fluids and contact physician• Transport if rapid improvement does not

occur

Advanced signs/symptoms EMS

Monitoring Core Temperature

• Consider purchasing flexible rectal thermistors and a thermometer

• Remember oral and tympanic temperatures will underestimate actual core temperature

Heat Stroke (Classical)

• Slow and steady rise in body core temperature over several days– Recognition

• Usually occurs in the infants, elderly or sick• Hot, red dry skin• Core temperature > 104°F• CNS dysfunction

Heat Stroke (Exertional)

• Cause - Thermoregulatory systems’ inability to dissipate heat causing increased heat storage.

• The body is overwhelmed by heat production from exercising muscles combined with inadequate heat loss because of environmental conditions

• Associated organ system failure• Fatal if not recognized and treated promptly

Heat Stroke – Incidence in Female Athletes

Heat Stroke - Recognition• CNS Manifestations

– Drowsiness– Confusion– Emotional instability– Disorientation– Staggering– Collapse– Unconsciousness– Loss of bowel and

bladder control

• Core Temperature > 104°F

• Tachycardia• Hyperventilation• Hypotension• CNS Manifestations

– Headache– Paresthesia– Dizziness

Heat Stroke - Management

• Prompt recognition - activate EMS• Immediate reduction of body temp.

– Remove from hot environment– Remove clothing and equipment– Rapid cooling (cold water immersion is

best 35 - 55°F) or ice bags, ice towels and air movement

– Monitor Temperature during cooling

Heat Stroke - Management

• Seizures may occur during cooling. • Do not give fluids by mouth if the

athlete is unresponsive.• Airway management• Monitor vital signs• Transport to hospital via EMS

Complications of Heat Stroke

• Shock• Rhabdomyolysis• Hyperkalemia • Acute renal failure*• Myocardial

infarction

• Liver damage• CNS damage• DeathPrevention is the key to avoiding death by heat stress!

Acute Exert ional Hyponatremia

• Defined as serum Na+ < 130mmol/L• Usually occurs in endurance athletes during

long events• Caused by replacement of sweat losses with

large amounts of water only (water intoxication)– Fluid moves into the tissues and causes tissue

swelling• This is a relatively rare but life-threatening

condition

• Description- Excess total body water with normal or slightly lower body sodium.– Body water excess– normal body sodium– ECV normal or slightly

expanded– No dehydration

• Inhibited water excretion or excessive AVP release

• Signs/Symptoms– Not usually

symptomatic– No expansion of ECV– No edema

*Usually involves abnormalrenal hormone response ordrugs (NSAIDS)

Euvolumic Hyponatremia

Hypervolumic Hyponatremia

• Description - Excess total body water and expanded ECV– Water excess– Sodium excess– No dehydration– Expanded ECV (BV)– Water or hypotonic fluid

overload (water intoxication)

• Signs/symptoms– Edema (hands and feet)– headache– dizziness– serum Na+ <130 mmol . l-1

– CNS symptoms - disorientation, confusion

– Pulmonary edema– cerebral edema– coma– cardiac/respiratory arrest

* Low-mod intensity lasting > 4 hr

Hypervolumic Hyponatremia –Incidence in Female Athletes

• Recognition– Disorientation– Altered mental status– Lethargy– Headache– Vomiting– Swelling of the hands

and feet– Rectal Temp < 104°F

• Can be Fatal– Cerebral Edema– Pulmonary Edema– Seizures

Most signs/symptoms come from tissue swelling

Acute Exertional Hyponatremia

Acute Exertional Hyponatremia

• Management– Activate EMS– Do Not administer fluids until a physician is

consulted– Blood tests are necessary for proper diagnosis– Monitor vital signs– IV line should be placed by EMS

Prevention is the Key!• Pre-participation Screening• Identify heavy sweaters• Identify those in poor

condition• Monitor athletes on

medications and supplements

• Monitor urinary indices of dehydration/hypohydration

• Fluid Replacement• Electrolyte Replacement• Increase time between

practices• Monitor environmental

conditions• Insure proper time period

for acclimatization• Allow for body cooling

whenever possible