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Hyper/hypothermia Flashcards

1
Q

What physiologic action causes increased heat loss?

A

vasodilation

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2
Q

What physiologic action causes heat conservation?

A

Vasoconstriction

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3
Q

What is the pathophys of hyperthermia?

A
  1. Na & H2O balance mediated by aldosterone
  2. Overheating/sweating → ↓ ECF volume
    A. ↓ Renal plasma flow → ↑ aldosterone secretion
  3. Body attempts to retain Na & H2O to ↑ ECF volume, causing:
    A. ↓ Na in urine & sweat
    B. K+ continues to be secreted by urine & sweat
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4
Q

What are heat injuries?

A
  1. Body’s inability to respond to environmental heat conditions (acclimation) → inadequate correction of ECF & electrolyte deficit

A. Heat cramps
B. Heat syncope
C. Heat exhaustion
D. Heat stroke

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5
Q

What substances can impair thermoregulation?

A
  1. TCA
  2. Anticholinergics
  3. ETOH
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6
Q

How do TCAs affect thermoregulation? What are examples?

A
  1. Inhibit sweating

2. [Elavil (amitriptyline), Tofranil (imipramine), Pamelor (desipramine), doxepin]

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7
Q

How do anticholinergics affect thermoregulation? What are examples?

A 
1. Inhibit sweating
A. Phenothiazines
1. Antihistamines
2. Parkinsonism meds 
3. Atropine/scopolamine
4. Neuroleptics
5. Antispasmodics
	[Compazine (prochlorperazine), Thorazine (chlorpromazine), 	Phenergan (promethazine)]
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8
Q

How does ETOH affect thermoregulation? What are examples?

A

Dehydration

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9
Q

What are the sxs of heat cramps?

A 
1. Profuse sweating w/spasms of large
muscles of extremities/core
2. Core temp normal to mildly ↑
3. Skin moist or dry
4. Skin cool or warm
5. Severe muscle cramps
Can occur hours after the activity has been completed
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10
Q

What is the pathophys of heat cramps?

A
  1. Pt often hyperventilates & produces ↑ sweat that has a high Na content
  2. Results in:
    A. Low-normal serum Na
    B. Lactic acid accumulates 2° to hyperventilation
    C. Resp Alkalosis
    D. May have mild hypokalemia
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11
Q

What are the general principles of heat cramps?

A
  1. Earliest symptom of a heat-related illness
  2. Often associated w/dehydration
  3. Work,exercise, or activity in a hot environment
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12
Q

Who are at most risk for heat cramps?

A

Infants, young children, & elderly at greatest risk

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13
Q

How can heat cramps be prevented?

A
  1. Avoid exercise or work during heat of the day
  2. Drink plenty of fluids
  3. Rest in cool or shaded area when possible
  4. Dress appropriately, avoid swaddling infant
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14
Q

How are heat cramps treated?

A
  1. Rest
  2. Cool body
  3. Fluid & salt replacement
    A. Mild – sport drinks
    B. Severe – IV NS
  4. Replace glucose prn
  5. K+ supplement if indicated
  6. Stretch/massage cramping muscles
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15
Q

What are the sxs of hypokalemia?

A
  1. Alkalosis
  2. Shallow respirations
  3. Irritability
  4. Confusion, drowsiness,
  5. Weakness, fatigue
  6. THready pulse
  7. Ileus
  8. Lethargy
  9. Arrhythmis, tahcycardia or bradycardia
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16
Q

What is heat syncope caused by?

A
  1. Caused by peripheral pooling of intravascular volume

A. Vasodilation redistributes volume to periphery → ↓ venous return → ↓ cerebral perfusion

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17
Q

What can contribute to heat syncope?

A
  1. Contributing factors

A. Dehydration & lack of acclimation

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18
Q

What is syncope secondary to in heat syncope?

A

2° to prolonged standing or orthostasis

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19
Q

What are the sxs of heat syncope?

A
  1. Transient syncope
  2. Core temp normal to mildly ↑
  3. Skin cool & moist
  4. Weak pulse
  5. Transient hypotension
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20
Q

How is heat syncope treated?

A
  1. Rest in supine position: trendelenburg
  2. Cool body
  3. Oral rehydration: normal saline if IV is needed, usually oral is sufficient
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21
Q

What is heat exhaustion caused by?

A
  1. Caused by prolonged heat exposure leading to:
    A. Primary dehydration (hypernatremic)
    B. Primary sodium depletion (hyponatremic)
    C. Combo most common
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22
Q

What can heat exhaustion lead to?

A
  1. Rapidly leads to heat stroke

2. Hypovolemia leads to hypoperfusion

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23
Q

Why would a person with heat exhaustion be hypernatremic?

A
  1. Due to primary H2O loss

2. Heated individual w/out H2O

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24
Q

Why would a person with heat exhaustion be hyponatremic?

A

Due to excessive sweating & hydrates w/H2O alone

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25
Q

What are the nonspecific sxs of heat exhaustion?

A 
1. Dizzy/lightheaded
A. NO CNS sx’s
2. Muscle cramps
3. Malaise
4. N/V
5. Headache
6. Core temp usually
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26
Q

What are the sxs of heat exhaustion specific to hypernatremia?

A
  1. Same nonspecific sxs
    • Tachycardia
    • Hypotension
    • Diaphoresis
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27
Q

What is the treatment for heat exhaustion?

A
  1. Rest in cool place: supine
  2. Draw BMP
    A. If severe hyponatremia 2° to H2O intoxication – give IV hypertonic saline
  3. Cool sports drink
    A. If unable to drink –give IV NS or LR
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28
Q

When should a pt with heat exhaustion be hospitalized?

A
  1. Mod/severe sx’s

2. Elderly w/comorbities

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29
Q

What are the sxs of hypotnatremia?

A
  1. HA
  2. Nausea
  3. vomiting
  4. Muscle cramps
  5. lethargy
  6. Restlessness
  7. Disorientation
  8. Depressed reflexes
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30
Q

What are the complications of severe and rapidly evolving hyponatremia?

A
  1. Seizures
  2. Coma
  3. Permanent brain damage
  4. respiratory arrest
  5. Brain stem herniation
  6. Death
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31
Q

Compare he sxs of heat exhaustion and heat stroke?

A 
1. Heat exhaustion
A. Moist and clammy skin
B. Pupils dilated
C. Normal or subnormal temperature
2. Heat Stroke
A. Dry hot skin
B. pupils constricted
C. Very high body temp
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32
Q

What causes heat stroke?

A

Due to thermoregulation dysfunction

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33
Q

What can heat stroke lead to?

A
  1. Can cause severe end-organ damage in minutes if not treated
  2. Rhabdomyolysis → Destroys cerebral, CV, hepatic & renal tissue
34
Q

What are the general principles of heat stroke?

A
  1. Includes altered mental status
  2. Pt can present w/any neurologic abnormality
    A. From confusion to coma
  3. True heat stroke does not sweat!

HOT DRY SKIN

35
Q

What are the predisposing factors for heat stroke?

A
  1. CV disease
  2. DM
  3. CF
  4. Alcoholism
  5. Obesity
  6. Recent febrile illness
36
Q

What are the sx of heat stroke?

A
  1. Core body temp >41° C (105.8° F)
  2. Stopped sweating
  3. Flushed, hot skin
  4. H/A
  5. Dizziness
  6. Nausea
  7. Diarrhea
  8. Visual changes
  9. (+) CNS sx’s
    A. LOC, irritability, hallucinations, delirium, seizures, combativeness, coma
37
Q

True/false: heat stroke is a life threatening emergency

38
Q

What are the critical sxs of heat stroke?

A
  1. Core temp 42° C (107.6° F) - 46° C (114.8° F)
  2. Hypotension
    A. Circulatory collapse
  3. Hyperventilation
    A. Resp alkalosis → metabolic acidosis
  4. Coagulopathy
    A. Hematuria
    B. Petechiae
    C. Ecchymosis
39
Q

Who is at most risk of heat stroke?

A

People at the extremes of age are susceptible

40
Q

What dx studies are used for heat stroke?

A
  1. (+) Hemoconcentration, DIC/Coagulopathy
  2. CBC w/plts
  3. ↓ PT, PTT
  4. ABG’s
  5. CMP
  6. CK & CK-MB (↑ in rhabdo)
  7. U/A
  8. Serum myoglobin
41
Q

What are the CBC results in heat stroke?

A

↑ WBC, ↓ platelets

42
Q

What are the CMP results in heat stroke?

A
  1. ↓ K+ (↑ K+ 2° ARF from rhabdomyolysis)
  2. ↑ SGOT
  3. ↑ Phosphate
43
Q

What are the U/A results in heat stroke?

A
  1. Casts, myoglobin (“machine oil urine”)
44
Q

What may be seen on EKG in heat stroke?

A

U waves from hypokalemia

45
Q

How is heat stroke treated?

A 
1. RAPID COOLING of patient to at least 39° C (102.2° F)
A. Cold water immersion
B. Cooling blankets
C. Ice packs
2. CV support
3. 2 large bore IV’s 
4. SaO2
5. Cardiac monitor
6. O2 @ 6-10 L/min via NC or mask
7. Serial rectal temp’s, BP, HR
8. Rehydrate w/1-2 L of .9% saline IV
A. Must not correct hyponatremia too fast
46
Q

When is an ice gastric lavage indicated for heat stroke?

A

If core temp >42° C (107.6° F), iced gastric lavage or peritoneal lavage

47
Q

When is a swan-ganz catheter indicated for heat stroke?

A

If hypotensive, need Swan-Ganz catheter to monitor CVP

48
Q

When is a foley catheter indicated for heat stroke?

A
  1. Foley cath to monitor UO

A. Goal 30-50 cc/hr

49
Q

What is the prognosis for heat stroke?

A 
1. Favorable
A. 80-90%  survive w/early Tx
2. Unfavorable
A. Persistent coma after cooling
B. Marked elevation in SGOT/SGPT
C. Hyperkalemia
D. Extreme hyperpyrexia
-Rectal Temp > 42° C (107.6° F)
50
Q

What is the definition of hypothermia?

A
  1. Core (rectal) temp
51
Q

What causes hypothermia?

A
  1. Exposure to cold weather or immersion in a cold body of water
  2. ETOH & drug abuse - common predisposing cause
52
Q

Define mild hypothermia

A
  1. Core temp 34°-36° C (93.2°-96.8° F)
  2. Awake & shivering
  3. Tachycardia, tachypnea, shivering
53
Q

Define moderate hypothermia

A
  1. Core temp 30°-34° C
    (86°-93.2° F)
  2. Altered mental status w/o shivering
  3. Bradycardia or A. Fib develop
54
Q

Define severe hypothermia

55
Q

What is the pathophys of hypothermia?

A
  1. As core temp drops below 32C, metabolism slows & ↓ in CO2 & O2 production
  2. Shivering stops 30°-32° C (86°- 90° F)
    A. HR, BP & CO ↓
    B. Confusion, lethargy, & coma develop
    C. Blood viscosity ↑, hemoconcentration & intravascular thrombosis & embolic events can occur
    D. EKG- Classic “J” wave
    E. Sinus brady → V fib → Asystole
56
Q

What are the EKG changes for hypothermia?

A
  1. Osborne or J waves
  2. May also have
    A. Atrial fib
    B. qt/QTc prolonged
57
Q

What can lead to metabolic hypothermia?

A
  1. Hypopituitarism
  2. Hypothyroidism/Myxedema
  3. Adrenal insufficiency
  4. Severe hypoglycemia
  5. Stroke
  6. .Acute head trauma,
  7. Wernicke’s disease
  8. Brain tumor
  9. Burns
  10. Sepsis
58
Q

What are the dx studies for hypothermia?

A
  1. CBC w/plts
  2. TSH, Free T4
  3. PT, PTT
  4. ABG’s
  5. CMP
    A. Hypoglycemia (↑ hemorrhagic pancreatitis 2° to exposure)
  6. Hypophosphatemia
  7. CK & CK-MB
  8. U/A
  9. Magnesium (↓)
59
Q

What are the rules for hypothermia treatment?

A
  1. 1st rule-hypothermic pt is not dead until warm & dead
  2. 2nd rule- NEVER handle a hypothermic pt roughly, this can precipitate deadly cardiac arrhythmia
60
Q

What is the treatment for mild hypothermia?

A

Get them warm: external heat, no alcohol!

61
Q

What is the treatment for moderate to severe hypothermia?

A
  1. Warm IV NS or LR
  2. Cardiac monitor
  3. 100% O2 by facemask
  4. Foley cath
  5. Hospitalize all pts w/ core temp
62
Q

What can active external warming lead to?

A 
1. This method can cause
peripheral vasodilation &
venous pooling leading to 
rewarming shock
2. Rewarming acidosis can
occur w/ rapid release
of lactic acid from tissues,
treated with 100% O2
63
Q

What must an alcoholic hypothermic pt receive?

A
  1. As a large number of hypothermic pts are alcoholics, give thiamine 100 mg after 100 ml of 50% dextrose IV
  2. Naloxone (Narcan) 1-4 mg to any unconscious pt
64
Q

What is active core rewarming and how is it performed? Who gets it?

A
  1. Pts w/ profound hypothermia w/cardiovasc. instability
  2. Warmed O2 by facemask or intubation
  3. Heated IV crystalloids
  4. Gastric lavage w/ warm water, warm bladder lavage
    A. warm peritoneal lavage, or warm pleural lavage
65
Q

What is the first sign of frostbite?

A

Pain & cold

66
Q

What are the general principles of frostbite?

A
  1. Numbness, blanched skin, cessation of cold discomfort
    A. If rewarmed at this stage, no tissue death occurs
  2. Pain & hypersensitivity can be present for several days or weeks
67
Q

What sxs will a true frostbite pt present with?

A

True frostbite patient will present w/ large, clear blisters in 24-48 hrs after freezing

68
Q

What are the sxs of superficial frostbite?

A

skin is pliable & tissue remains soft beneath the surface

69
Q

How high should a hypothermic pt be rewarmed to?

A

95 degrees F

70
Q

What are the sxs of deep frostbite?

A

tissues feel woody or stony on palpation

71
Q

What are hypothermic pts with a ventricular arrhythmia treated with?

A
  1. Britilium

2. NOT lidocaine or procainamide!!!

72
Q

When are skin color changes seen in a frostbite pt?

A

Can take several weeks before lines of demarcation between blackened dead tissue & healthy viable tissue are formed

73
Q

What is the pathophys of frostbite?

A
  1. Tissue freezing caused by formation of ice crystals in tissue
  2. Occurs when skin temp drops to 4°-10° C (14°-28° F)
74
Q

What is first degree frostbite?

A

freezing without blistering after rewarming

75
Q

What is second degree frostbite?

A

freezing with clear blisters

after rewarming

76
Q

What is third degree frostbite?

A

Freezing with death of skin, hemorrhagic blisters & SQ involvement
after re-warming

77
Q

What is fourth degree frostbite?

A

Freezing w/full thickness involvement; loss of body part after re-warming

78
Q

How is frost bite treated?

A
  1. Rapid rewarming is mainstay of treatment
    A. Warm (not hot) water bath 15 min up to 1 hr
  2. Mild frostbite
    A. Remove wet clothes & apply constant warmth
  3. Full Thickness frostbite
    A. Rapid rewarming w/water bath 40°-42° C (104°-107.6° F)
  4. If frostbite present, hypothermia can also be present, so Tx same as hypothermia
  5. After thawing of extremity, elevate to reduce edema
79
Q

When should a frostbite pt be hospitalized?

A

Hospitalize all 2nd and 3rd degree frostbite & w/extensive areas of 1st degree

80
Q

What meds should be given for frostbite?

A
  1. Ibuprofen 400-600 mg PO Q8-12 h x 72 hrs
  2. dT or TDaP prophylaxis
  3. After rewarming, abx prophylaxis & debride clear blisters
  4. Whirlpool treatments w/warm abx sol’n for debridement

Gen Med: Emergency Med (13 decks)

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