Heat Related Injury and Illness Flashcards

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1
Q

The 4 ways the body dissipates heat

A
  1. Radiation (infared rays)
  2. Convection (air/water across skin)
  3. Conduction (physical Contact)
  4. Evaporation (Sweat)
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2
Q

Pathophysiology of a Fever

A

Temperature elevation due to activity of the hypothalamus, in response to cytokines triggered by infection or sterile inflammation

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3
Q

Pathophysiology of Hyperthermia

A

Temperature elevation due to uncontrolled heat generation (i.e. muscular hyperactivity), which can generate temperatures higher than a fever, with greater risk of thermal injury to tissues.
Unlike fever, hyperthermia involves complete loss of thermal control

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4
Q

Does Fever or Hyperthermia involve complete loss of thermal control?

A

Hyperthermia

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5
Q

As body temp incr, skin sensors and warm blood stimulates the anterior hypothalamus, which stimulates ….

A
  • Vasodilatation
  • Increased Cardiac Output
  • Increased Respiratory Rate
  • Increased Sweat Production
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6
Q

as temp incr above ____, most heat loss occurs thru sweating.

A

95F

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7
Q

As relative humidity incr above ____%, sweating becomes ineffective

A

75%

bc moisture on skin cannt transfer into air bc theres not enough of a humidity difference b/w skin and air

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8
Q

Factors contributing to incr heat illness danger

A
  • High heat
  • high humidity
  • lack of wind
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9
Q

Types of heat illness

A
  • Heat cramps
  • Heat exhaustion
  • Heat stroke
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10
Q

Heat cramps

A
  • painful, involuntary spasmodic muscle cramps that occur in heavily exercised muscles in hot and humid environments
  • mildest form of heat injury
  • ET: e- imbalance
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11
Q

Do heat cramps results in hyper or hyponatremia?

A

hyponatremia bc you sweat and replace water but not salt

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12
Q

Typical body temp during muscle cramps?

A

norm, body is still thermoregulating

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13
Q

Heat cramps trmnt

A
  • firm passive muscle stretching (ankel dorsiflexion for calf cramp)
  • rest in cool space
  • Oral fluids (1-2L water with 2 tsp salt)
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14
Q

When to seek immediate attention for heat cramps?

A
  • Cramps cannot be controlled
  • Insufficient fluid intake due to nausea/vomiting
  • Significant weakness
  • Profuse sweating not controlled in air-conditioned environment
  • May have in addition to heat exhaustion or heat stroke
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15
Q

Heat exhaustion can very quickly lead to ______ if not treated ASAP

A

heat stroke

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16
Q

Heat exhaustion is determined by a core temp >______

A

An illness resulting from prolonged, heavy activity in a hot environment with subsequent dehydration, electrolyte depletion, and rectal temperature 37.8 °C - 40 °C (100 °F - 104 °F)

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17
Q

Heat stroke is determined by a core temp >_____

A

A life-threatening heat illness characterized by extreme hyperthermia (core temperature >40 °C [104.0 °F]), dehydration, and neurologic manifestations

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18
Q

Which two types of heat illness are thermoregulation issues?

A

Heat exhaustion and heat stroke

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19
Q

Which heat illness is due to electrolyte abnorm?

A

Heat cramps

20
Q

Heat exhaustion vs heat stroke (SS & trmnt)

A
21
Q

Exertional vs Non-exertional heat stroke

A
  • Exertional = Young althete on the field for too long
  • Non-exertional = old women watching the game in the shade
22
Q

Meds that impair heat dissipation (risks for elderly)

A

phenothiazines, anticholinergics, antihistamines, beta-blockers

  • Anticholinergic properties (atropine)
  • Antiepileptic (topiramate)
  • Antihistamines
  • Glutethimide (Doriden)
  • Phenothiazines
  • Tricyclic antidepressants
  • Amphetamines, cocaine, “ecstasy”
  • Ergogenic stimulants (e.g., ephedrine, ephedra)
  • Lithium
  • Diuretics
  • β-Blockers
  • Ethanol
23
Q

Predisposing factors for heat illness (not due to illness)

A

Lack of acclimatization
Low physical fitness
Excessive body weight
Dehydration
Advanced age
Young age

24
Q

Predisposing factors for heat illness (medical co-morbidities)

A
  • Inflammation and fever
  • Viral infection
  • Cardiovascular disease
  • Diabetes mellitus
  • Gastroenteritis
  • Rash, sunburn, and previous burns to large areas of skin
  • Seizures
  • Thyroid storm
  • Neuroleptic malignant syndrome
  • Malignant hyperthermia
  • Sickle cell trait
  • Cystic fibrosis
  • Spinal cord injury
25
Q

Heat exhaustion or stroke?

  • Generalized malaise, weakness, headache, muscle and abdominal cramps, nausea, vomiting, hypotension, tachycardia.
  • Rectal temperature is usually normal.
  • Sweating is usually present.
A

exhaustion

26
Q

Heat exhaustion or stroke?

  • Neurologic manifestations (seizures, tremor, hemiplegia, coma, psychosis, other bizarre behavior)
  • Evidence of dehydration (poor skin turgor, sunken eyeballs)
  • Tachycardia, hyperventilation
  • Skin is hot, red, and flushed
  • Sweating is often (not always) absent, particularly in elderly patients
A

stroke

27
Q

why are kids under 4 and elderly over 65yo at higher risk for heat illness?

A

kids CNS is not fully developed and cant thermoregulate as well
Elderly ppl have deterioating CNS

28
Q

Which labs can differentiate b/w heat exhaustion and stroke?

A

Mild or absent increases in heat exhaustion:
creatine phosphokinase (CPK)
aspartate aminotransferase (AST)
lactate dehydrogenase (LDH)
alanine aminotransferase (ALT)

29
Q

Possible lab abnormalities for heat exhaustion and stroke

A
  • HIGH BUN, creatinine, hematocrit
  • Hypo/hypernatremia, hyper/hypoK+
  • HIGH LDH, AST, ALT, CPK, Bilirubin
  • Lactic acidosis, resp alkalosis (hyperventilation)
  • Myoglobinuria, hypofibrinogenemia, fibrinolysis, hypocalcemia
30
Q

Heat exhaustion trmnt

A
  • get out of the heat
  • fluids 2L q4hr
  • salt replacement (1/4 tsp salt in 1L water)
  • if IV fluids if unable to drink
31
Q

IV Fluids for heat exhaustion?

A
  • young athletes -> NS IV (3-4L over 6-8hrs)
  • elderly patients -> consider using D5½NS IV with the rate titrated to cardiovascular status.
32
Q

Heat stroke trmnt

A
  • rapid cooling
  • rmv clothes
  • if unconscious -> roll pt on their side
  • protect airway and give nasal O2 at 4L/min to keep SatO2 >90%
  • Monitor body temp q 5min (rectal temp goal: 38C (102.2F) within 30-60min)
  • Stop active cooling when 38-39 °C to prevent overcooling
  • Continue monitoring for thermal instability for up to 6 hours
33
Q

The goal of active cooling is to drop the temp down to ________ within ______min

A

38C (102.2F) within 30-60min

Stop once this is reached to prevent overcooling

34
Q

Monitor body temp q ____min

A

5

35
Q

Ways to cool a person with heat stroke?

A
  • spray bottle + fan
  • immersion in tepid water (15C, 59F) is preferred over ice immersion to minimize risk of shivering
  • ice bath (more effective than other intrusive options like ice cold stomach lavage)
36
Q

Why should you NOT cool a person by puting ice packs on their bare skin (axilla, neck, groin)

A

they increase peripheral vasoconstriction and may induce shivering.

37
Q

Why are antipyretics ineffective at cooling a person with heat stroke?

A

the hypothalamic set point during heat stroke is normal despite the increased body temperature.
Antipyretics are agents that try to decrease a fever by telling the hypothalamus to decrease the set body temperature.
Trying to turn the temperature down won’t do anything if the room is on fire

38
Q

Why are Arctic sun (cooling pads) not preferred to cool a person with heat stroke?

A

not quick enough

39
Q

Why should vasopressors be avoided if possible in pt with heat stroke?

A

may cause cutaneous vasoconstriction which impairs heat release

40
Q

management of heat stroke

A
  • Intubate a comatose patient, or one with extreme rigidity, or in status epilepticus
  • Otherwise, nasal O2
  • Insert Foley catheter
  • Continuous ECG monitoring is recommended.
  • Insert at least two large-bore IV lines and begin IV hydration with normal saline (NS) or Lactated Ringer.
  • Draw initial laboratory studies: Electrolytes, complete blood count, blood urea nitrogen, creatinine, AST, ALT, CPK, LDH, glucose, PT (INR), PTT, platelet count, Ca2+, lactic acid, Coag profile, and arterial blood gases.
41
Q

Hyperthermia complications

A
  • Rhabdomyolysis
  • Acute hepatic failure (rarely leading to fulminant failure requiring transplantation)
  • Seizure
  • Aspiration pneumonia -> ARDS
  • Stress-induced cardiomyopathy
  • Disseminated Intravascular Coagulation (DIC)
  • Hypoglycemia
  • Hyponatremia (likely hypernatremic if dehydrated)
42
Q

Heat stroke complication trmnts

Hypotension

A

Vigorous hydration with normal saline or Ringer lactate

43
Q

Heat stroke complication trmnts

Shivering

A
  • Benzodiazepines, muscle relaxation and anti-seizure effects
  • Ketamine, help control agitation
  • Opioids, treat pain if source of agitation (avoid fentanyl if concerned of serotonin syndrome)
  • Magnesium
  • Buspirone 30mg PO

Caution, these can decr resp drive (especiially opiates). if you have to use, knock them out and intubate

44
Q

Heat stroke complication trmnts

Acidosis

A

Use bicarbonate judiciously (only in severe acidosis)

usu you just treat the underlying ET

45
Q

Heat stroke complications

Rhabdomyoloysis is a concern for ____

A

compartment syndrome

46
Q

heat stroke prognosis

A
  • Most patients recover completely within 48 hr.
  • Central nervous system injury is permanent in 20% of cases.
  • Mortality rate can exceed 30% in patients with prolonged and severe hyperthermia.
  • Delayed access to cooling is the leading cause of morbidity and mortality in persons with heat stroke.
47
Q

heat stroke complications trmnt

Agitation

A

Low-dose ketamine