Hyper/hypothermia Flashcards
1
Q
What physiologic action causes increased heat loss?
A
vasodilation
2
Q
What physiologic action causes heat conservation?
A
Vasoconstriction
3
Q
What is the pathophys of hyperthermia?
A
- Na & H2O balance mediated by aldosterone
- Overheating/sweating → ↓ ECF volume
A. ↓ Renal plasma flow → ↑ aldosterone secretion - Body attempts to retain Na & H2O to ↑ ECF volume, causing:
A. ↓ Na in urine & sweat
B. K+ continues to be secreted by urine & sweat
4
Q
What are heat injuries?
A
- 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
5
Q
What substances can impair thermoregulation?
A
- TCA
- Anticholinergics
- ETOH
6
Q
How do TCAs affect thermoregulation? What are examples?
A
- Inhibit sweating
2. [Elavil (amitriptyline), Tofranil (imipramine), Pamelor (desipramine), doxepin]
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)]
8
Q
How does ETOH affect thermoregulation? What are examples?
A
Dehydration
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
10
Q
What is the pathophys of heat cramps?
A
- Pt often hyperventilates & produces ↑ sweat that has a high Na content
- Results in:
A. Low-normal serum Na
B. Lactic acid accumulates 2° to hyperventilation
C. Resp Alkalosis
D. May have mild hypokalemia
11
Q
What are the general principles of heat cramps?
A
- Earliest symptom of a heat-related illness
- Often associated w/dehydration
- Work,exercise, or activity in a hot environment
12
Q
Who are at most risk for heat cramps?
A
Infants, young children, & elderly at greatest risk
13
Q
How can heat cramps be prevented?
A
- Avoid exercise or work during heat of the day
- Drink plenty of fluids
- Rest in cool or shaded area when possible
- Dress appropriately, avoid swaddling infant
14
Q
How are heat cramps treated?
A
- Rest
- Cool body
- Fluid & salt replacement
A. Mild – sport drinks
B. Severe – IV NS - Replace glucose prn
- K+ supplement if indicated
- Stretch/massage cramping muscles
15
Q
What are the sxs of hypokalemia?
A
- Alkalosis
- Shallow respirations
- Irritability
- Confusion, drowsiness,
- Weakness, fatigue
- THready pulse
- Ileus
- Lethargy
- Arrhythmis, tahcycardia or bradycardia
16
Q
What is heat syncope caused by?
A
- Caused by peripheral pooling of intravascular volume
A. Vasodilation redistributes volume to periphery → ↓ venous return → ↓ cerebral perfusion
17
Q
What can contribute to heat syncope?
A
- Contributing factors
A. Dehydration & lack of acclimation
18
Q
What is syncope secondary to in heat syncope?
A
2° to prolonged standing or orthostasis
19
Q
What are the sxs of heat syncope?
A
- Transient syncope
- Core temp normal to mildly ↑
- Skin cool & moist
- Weak pulse
- Transient hypotension
20
Q
How is heat syncope treated?
A
- Rest in supine position: trendelenburg
- Cool body
- Oral rehydration: normal saline if IV is needed, usually oral is sufficient
21
Q
What is heat exhaustion caused by?
A
- Caused by prolonged heat exposure leading to:
A. Primary dehydration (hypernatremic)
B. Primary sodium depletion (hyponatremic)
C. Combo most common
22
Q
What can heat exhaustion lead to?
A
- Rapidly leads to heat stroke
2. Hypovolemia leads to hypoperfusion
23
Q
Why would a person with heat exhaustion be hypernatremic?
A
- Due to primary H2O loss
2. Heated individual w/out H2O
24
Q
Why would a person with heat exhaustion be hyponatremic?
A
Due to excessive sweating & hydrates w/H2O alone
25
What are the nonspecific sxs of heat exhaustion?
```
1. Dizzy/lightheaded
A. NO CNS sx’s
2. Muscle cramps
3. Malaise
4. N/V
5. Headache
6. Core temp usually
```
26
What are the sxs of heat exhaustion specific to hypernatremia?
1. Same nonspecific sxs
2. + Tachycardia
3. + Hypotension
4. + Diaphoresis
27
What is the treatment for heat exhaustion?
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
28
When should a pt with heat exhaustion be hospitalized?
1. Mod/severe sx’s
| 2. Elderly w/comorbities
29
What are the sxs of hypotnatremia?
1. HA
2. Nausea
3. vomiting
4. Muscle cramps
5. lethargy
6. Restlessness
7. Disorientation
8. Depressed reflexes
30
What are the complications of severe and rapidly evolving hyponatremia?
1. Seizures
2. Coma
3. Permanent brain damage
4. respiratory arrest
5. Brain stem herniation
6. Death
31
Compare he sxs of heat exhaustion and heat stroke?
```
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
```
32
What causes heat stroke?
Due to thermoregulation dysfunction
33
What can heat stroke lead to?
1. Can cause severe end-organ damage in minutes if not treated
2. Rhabdomyolysis → Destroys cerebral, CV, hepatic & renal tissue
34
What are the general principles of heat stroke?
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
What are the predisposing factors for heat stroke?
1. CV disease
2. DM
3. CF
4. Alcoholism
5. Obesity
6. Recent febrile illness
36
What are the sx of heat stroke?
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
True/false: heat stroke is a life threatening emergency
True
38
What are the critical sxs of heat stroke?
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
Who is at most risk of heat stroke?
People at the extremes of age are susceptible
40
What dx studies are used for heat stroke?
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
What are the CBC results in heat stroke?
↑ WBC, ↓ platelets
42
What are the CMP results in heat stroke?
1. ↓ K+ (↑ K+ 2° ARF from rhabdomyolysis)
2. ↑ SGOT
3. ↑ Phosphate
43
What are the U/A results in heat stroke?
1. Casts, myoglobin (“machine oil urine”)
44
What may be seen on EKG in heat stroke?
U waves from hypokalemia
45
How is heat stroke treated?
```
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
When is an ice gastric lavage indicated for heat stroke?
If core temp >42° C (107.6° F), iced gastric lavage or peritoneal lavage
47
When is a swan-ganz catheter indicated for heat stroke?
If hypotensive, need Swan-Ganz catheter to monitor CVP
48
When is a foley catheter indicated for heat stroke?
1. Foley cath to monitor UO
| A. Goal 30-50 cc/hr
49
What is the prognosis for heat stroke?
```
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
What is the definition of hypothermia?
1. Core (rectal) temp
51
What causes hypothermia?
1. Exposure to cold weather or immersion in a cold body of water
2. ETOH & drug abuse - common predisposing cause
52
Define mild hypothermia
1. Core temp 34°-36° C (93.2°-96.8° F)
2. Awake & shivering
3. Tachycardia, tachypnea, shivering
53
Define moderate hypothermia
1. Core temp 30°-34° C
(86°-93.2° F)
2. Altered mental status w/o shivering
3. Bradycardia or A. Fib develop
54
Define severe hypothermia
1. Core temp
55
What is the pathophys of hypothermia?
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
What are the EKG changes for hypothermia?
1. Osborne or J waves
2. May also have
A. Atrial fib
B. qt/QTc prolonged
57
What can lead to metabolic hypothermia?
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
What are the dx studies for hypothermia?
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
What are the rules for hypothermia treatment?
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
What is the treatment for mild hypothermia?
Get them warm: external heat, no alcohol!
61
What is the treatment for moderate to severe hypothermia?
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
What can active external warming lead to?
```
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
What must an alcoholic hypothermic pt receive?
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
What is active core rewarming and how is it performed? Who gets it?
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
What is the first sign of frostbite?
Pain & cold
66
What are the general principles of frostbite?
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
What sxs will a true frostbite pt present with?
True frostbite patient will present w/ large, clear blisters in 24-48 hrs after freezing
68
What are the sxs of superficial frostbite?
skin is pliable & tissue remains soft beneath the surface
69
How high should a hypothermic pt be rewarmed to?
95 degrees F
70
What are the sxs of deep frostbite?
tissues feel woody or stony on palpation
71
What are hypothermic pts with a ventricular arrhythmia treated with?
1. Britilium
| 2. NOT lidocaine or procainamide!!!
72
When are skin color changes seen in a frostbite pt?
Can take several weeks before lines of demarcation between blackened dead tissue & healthy viable tissue are formed
73
What is the pathophys of frostbite?
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
What is first degree frostbite?
freezing without blistering after rewarming
75
What is second degree frostbite?
freezing with clear blisters
| after rewarming
76
What is third degree frostbite?
Freezing with death of skin, hemorrhagic blisters & SQ involvement
after re-warming
77
What is fourth degree frostbite?
Freezing w/full thickness involvement; loss of body part after re-warming
78
How is frost bite treated?
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
When should a frostbite pt be hospitalized?
Hospitalize all 2nd and 3rd degree frostbite & w/extensive areas of 1st degree
80
What meds should be given for frostbite?
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
