L50 Environmental

Question 1

Definition of hypothermia

Answer 1

Core temp below 35C/95F

Question 2

Stage I of hypothermia

Answer 2

Violent shivering, pallor, distal cyanosis, alert but confused with poor coordination
32-34.9C

Question 3

Stage II hypothermia

Answer 3

Conscious, chivering ceases, bradycardia, arrhythmia, undressing
28-31.9C

Question 4

Stage III hypothermia

Answer 4

Unconscious

24-27.9C

Question 5

Stage IV hypothermia

Answer 5

No vital signs, core temp less than 24C

Question 6

Systemic pathogenesis of hypothermia

Answer 6

Initial vasoconstriction with sympathetic discharge increases HR and basal metabolism up to 6X, shivering to produce heat
With continued decrease in temperature, respiratory drive, HR, BP decline, arrhythmia likely
Cold diuresis increases blood viscosity decreasingO2 sat, hyperkalemia, lactic acidosis
Pulmonary edema, multiorgan failure

Question 7

Pathogenesis of frostbite

Answer 7

Freezing produces ice crystals that damage the cell membrane
Hypoxia from vasoconstriction, thrombosis; endothelial damge leads to release of mediators tha increase vascular permeability and edema
Inflammatory mediators: thromboxane cause thrombosis

Question 8

Appearance of superficial and deep frostbite

Answer 8

Superficial: Intact pinprick sensation, indents with pressure, may have large blisters, milky fluid

Deep: wooden skin, frozen steak appearance, small hemorrhagic vesicles, local cyanosis

Question 9

What altitudes constitute High altitude, Very high altitude, Extreme altitude?

Answer 9

High: 5,000-8,000
Very High: 11,500-18,000
Extreme: over 18,000ft

Altitude illness generally starts around 2,500m or 8,000 feet

Question 10

What factors change with altitude acclimatization?

Answer 10

Increased capillaries: brain, muscle, heart
Increased myoglobin in tissues
Polycythemia with increased 2,3 DPG

Question 11

When does high altitude deterioration occur?

Answer 11

Above 5500m (18,000ft)

Question 12

At what altitudes are retinal hemorrhages seen and what is the prevalence?

Answer 12

Half of those sleeping above 16,000ft will get them

Generally reversible

Question 13

Sx of acute mountain sickness

Answer 13

Headache + 1 of following:
nausea, vomiting, dizziness, fatigue, insomnia
Variable intensity of Sx and combination
Over 2500m or 8,000ft

Question 14

SSx of HACE

Answer 14

Sx: same as AMS
Signs: lassitude, truncal ataxia, altered mental status such as drowsiness or loss of consciousness, often mild fever

Question 15

SSx HAPE

Answer 15

Sx: initially inappropriate dyspnea during exercise, reduced performance, mild fever; advanced illness has orthopnea, pink frothy sputum, drowsiness

Signs: tachypnea, arterial O2 sat low, mild fever, signs of HACE with advanced stages

Question 16

Pathogenesis of HAPE and HACE

Answer 16

Assoc with rapid ascent over 2500m
Pulmonary hypoxia causes pulmonary vasoconstriction leading to HTN and edema in interstitium
Tachycardia and RV overload, marked reduction in O2 w/o changes in pH or CO2
Vasogenic cerebral edema with micro hemorrhages esp in corpus callosum

Question 17

Why do patients with HAPE have a fever?

Answer 17

Noninflammatory leak provokes an inflammatory response

Question 18

Definition of hyperthermia and at what temp do you start to have heat injury?

Answer 18

Hyperthermia = greater than 37.2C

Heat injury from temp above 40C

Question 19

Who is at highest risk for heat injury?

Answer 19

Very young and elderly because of poor thermal control

Heat exposure with excessive activity prior day

Question 20

SSx of heat illness

Answer 20

Heat Cramps: cramps, N/V, sweating, headache, tinnitus, normal temp

Heat Exhaustion: continuation from heat cramps, profuse sweating, anxiety, irritability, elevated temp

Heat stroke: continuation from above, warm and dry, convulsions, coma, temp over 41C/106F

Question 21

What causes the muscle cramps in heat illness?

Answer 21

Loss of electrolytes: Na, Cl, and also water

Question 22

Core temp in heat exhaustion

Answer 22

37. 5-39C

99. 5-102.2F

Question 23

Core temp in heat stroke

Answer 23

over 41C or 106F

Question 24

Key Sx in heat stroke

Answer 24

dry skin, altered consciousness

Question 25

Pathogenesis of heat stroke

Answer 25

Generalized vasodilation leads to pooling of blood and inefficient blood circulation
Heat related nitrosylation of ryanodine receptor in muscle releases Ca into cytoplasm causing sustained contractions that generate more heat
Necrosis of myocardium and skeletal muscle–rhabdomyolysis

Question 26

Complications of heat stroke

Answer 26

Systemic temp above 42C incompatible with life
Rhabdomyolysis
Hyperkalemia–arrhythmias
Cerebral edema
Multiple organ failure: ARDS, renal, hepatic failure; GI hemorrhage

Question 27

Pathophysiology of burns

Answer 27

Heat induced denaturation of protein leads to tissue coagulation necrosis
Cytokines released cause mast cells to degranulate leading to hyperemia and edema