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Aeromed BM > Altitude Physiology > Flashcards

Altitude Physiology Flashcards

1
Q

Structure of the atmosphere

A

Troposphere - Sea level to 26,000/53,000ft (poles vs. equator) ** mean temperature lapse rate of -1.98*C per 1000ft** (Mt. Everest is 29,000 ft high)

Stratosphere - 26,000/53,000ft to 30 miles

Mesosphere - 30 miles to 50 miles

Thermosphere - 50 miles to 435 miles

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2
Q

Physiological zones of the atmosphere

A

Efficient zone - sea level to 10,000ft (760mm Hg to 523mm Hg)

Deficient zone - 10,000 to 50,000ft (523mm Hg to 87mm Hg) 30min till unconsciousness

Space equivalent zone - 50,000ft and up

63,000ft, blood boils due to gas release

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3
Q

Composition of air

A

78% Nitrogen (N2)

21% Oxygen (O2)

1% other (.03% CO2)

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4
Q

Barometric pressure

A

Measure of pressure on earths surface from water and gases in atmosphere (760mm or 29,92 Hg at sea level)

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5
Q

Composition vs. pressure

A

Composition of atmosphere remains constant at every altitude

Pressure decreases with altitude

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6
Q

Significant altitudes

A

0ft - 760mm Hg - 1atm

18,000ft - 380mm Hg - 1/2atm

34,000ft - 190mm Hg - 1/4atm

48,000ft - 95mm Hg - 1/8atm

63,000ft - 47mm Hg - 1/16atm

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7
Q

Partial pressure of gases

A

O2 - 21% or 0.21 composition in atm

Ex) atmosphere pressure at 18,000ft = 380mm Hg
PO2? 0.21*380 = 79.8mm Hg partial pressure of O2 at 18,000ft

*DALTON’s LAW
Pressure total = sum of partial pressures of each gas in atm

(Pt = PO2 + PN2 + PCO2 …)

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8
Q

Circulatory system

A

Oxygen/nutrients to cells

Transports waste

Assists temperature regulation

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9
Q

Circulatory components

A

Arteries (oxygenated)

Veins (deoxygenated)

Capillaries - arteries to veins; transfers O2, CO2, nutrients, waste; one cell thick; gas diffusion

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10
Q

Blood

A

Plasma - 55% of blood, transports nutrients, CO2 and hormone transport

WBC - no hemoglobin, fights infection/inflammation

Platelets - produced in bone marrow, coagulates blood

RBC - transport 98.5% of O2; composed of 97% hemoglobin (protein with 4 oxygen binding sites) which transports 20% of CO2 in the body

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11
Q

Respiratory system

A

Intake O2

Remove CO2

Maintain heat balance

Maintain PH base balance 7-8 (slightly alkaline)

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12
Q

Phases of repiration

A

Inhalation is active (diaphragm lowers)

Exhaustion is passive (diaphragm relaxes)

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13
Q

Components of respiratory system

A

In relative order:

Oral-nasal passage

Oral passage

Pharynx

Larynx

Trachea

Bronchi

Bronchioles

Alveolar ducts

Alveoli (air sacs)

Pulmonary vein (where RBCs receives O2 and give CO2 by diffusion)

Diaphragm

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14
Q

Law of gas diffusion

A

Gas molecules of higher pressure move in the direction of gas molecules of a lower pressure

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15
Q

*Hypoxia

A

State of oxygen deficiency significant enough to cause impairment of function

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16
Q

*Hypoxic hypoxia

A

Reduced PO2 in the lungs, usually due to altitude increases (lower gas pressure)

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17
Q

*Hypemic Hypoxia

A

Inability of the blood to accept adequate oxygen (due to carbon monoxide [CO] or blood loss)

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18
Q

*Stagnant hypoxia

A

Oxygen carrying capacity is adequate but circulation is inadequate (pressure point or G-Forces)

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19
Q

Histoxic hypoxia

A

Inability of tissue to accept or use oxygen (cyanide, alcohol, narcotics)

20
Q

Symptoms of hypoxia (what you could feel)

A 
Air hunger
Apprehension
Fatigue
Nausea
Headache
Dizziness
Blurred vision
Hot/cold flashes
Euphoria
Belligerence
Numbness
Tingling
Denial
21
Q

Signs of hypoxia

A

Hyperventilation
Cyanosis
Poor judgement
Lack of coordination

22
Q

Factors modifying hypoxia symptoms

A 
Pressure altitude
Rate of ascent
Time at altitude
Temperature
Physical activity
Individual factors
Physical fitness
Self imposed stress (D.E.A.T.H.)
23
Q

Hypoxia prevention

A

Limit time at alt.
Pressurized cabin
Minimize stress
100% O2

24
Q

Hypoxia treatment

A

Descend to safe alt.

100% O2

25
Q

Indifferent stage of hypoxia

A

Sea level to 10,000ft

O2 saturation 98% - 90%

Decrease night vision to 4,000ft

Acuity, color perception lessons

26
Q

Compensatory stage of hypoxia

A

10,000-15,000ft

O2 at 89% - 80%

Impaired efficiency, drowsiness, poor judgement, decreased coordination

27
Q

Disturbance stage of hypoxia

A

15,000 - 20,000ft

O2 at 79% - 70%

Decreased memory, judgement, reliability, poor understanding

Happy drunk/mean drunk

Blurred vision, impaired hearing, poor coordination

Decreased feeling/numbness

28
Q

Critical stage of hypoxia

A

20,000ft and up

O2 at 69% - 60%

Loss of consciousness, convulsions, death

29
Q

Time of Useful Consciousness (TUC)

A 
43,000ft - 9 to 12 sec
40,000ft - 15 to 20 sec
35,000ft - 30 to 60 sec
30,000ft - 1 to 2 min
28,000ft - 2.5 to 3 min
25,000ft - 3 to 5 min
22,000ft - 8 to 10 min
18,000ft - 20-30min

*In a rapid decompression(RD), times are reduced by half

30
Q

Hyperventilation

A

Excessive rate of breath resulting in abnormal loss of CO2 from the blood (alkalosis)… >16 breaths/min

31
Q

Causes of hyperventilation

A

Emotional (fear, anxiety)

Positive pressure breathing

Hypoxia

32
Q

Symptoms of hyperventilation

A 
Tingling
Muscle spasms
Hot/cold sensation
Visual impairment
Dizziness
Unconciousness
33
Q

Hyperventilation corrective actions

A

Don’t panic
Control your breathing
Talk out loud, read a checklist
Check you oxygen equipment - could be hypoxia

34
Q

Hypoxia vs. hyperventilation

A

Hypoxia - above 10,000ft; cyanosis only occurs in hypoxia

Hyperventilation - below 10,000ft; muscle cramps only in hyperventilation

35
Q

Gas dysbarism

A

Types - trapped gas and evolved gas

Syndrome resulting from the effects, excluding hypoxia, of a pressure differential between ambient and internal body pressures

36
Q

Boyle’s law

A

Volume of gas is inversely proportional to its pressure when temperature is constant

Gas volume increases as body rises higher in altitude

37
Q

Prevention of abnormal gas

A

Avoid soda, large amounts of water

Dont chew gum during ascent

Keep regular bowel movement

Off-gas as necessary

38
Q

Treatment of ear/sinus blocks

A

Ascent - (rare) land and refer to flight surgeon

Descent - stop descent and clear by valsalva… if unable, climb and repeat. Descend slowly

39
Q

Barodentalgia

A

Tooth pain due to gas expansion on ascent

Land and refer to dental

40
Q

Evolved gas dysbarism (decompression sickness)

A

Occurs due to reduction in atmospheric pressure

As pressure decreases, gases dissolved in body fluid released as bubbles

41
Q

Henry’s law

A

Amount of gas dissolved in a fluid is directly proportional to the pressure on that fluid (soda bottle - evolved gas dysbarism)

42
Q

Evolved gas disorders

A

Type 1:

Bends - N2 bubbles trapped in joints (painful)
Skin manifestations - N2 bubbles form under skin along nerve tracts

Type 2:

Chokes - N2 bubbles block pulmonary vessels, burning sternum, desire to cough, sense of suffocation
Central nervous system disorder - N2 bubbles trapped in brain or against spinal chord. Paralysis, disturbances, one sided tingling

43
Q

Factors influencing Evolved Gas Disorders

A

Rate of ascent

Exercise

Altitude

Body fat

Age

Duration of exposure

Repeated exposure

44
Q

Decompression sickness prevention

A

Denitrogenation - required for unpressurized flight above 18,000ft

30min of pure O2 decreases N2 by 30%

Pressurized flight suit is a pressure at 10,000ft altitude pressure and below

45
Q

Decompression sickness treatment

A

Descend

Immobilize affected area

100% O2

Land at nearest treatment available

Compression > 1atm absolute

*Scuba divers have 24 hours no flying

Aeromed BM (13 decks)

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