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Respiratory > Lungs at extreme conditions > Flashcards

Lungs at extreme conditions Flashcards

1
Q

what happens to FiO2 at altitude

A

constant

- same amount of oxygen at high altitudes, just different pressures

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2
Q

what is the alveolar gas equaiton

A

PAO2 = PiO2 - PaCO2/ R

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3
Q

what is PiO2 at sea level

A

21kPa

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4
Q

what is an equation for PiGas

A

PiGas = Patm x FiGas

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5
Q

what happens to lungs as you ascend

A

CO2 drops because hypoventilation occurs

  • become alkalotic initially so pH rises
  • pressure of inspired air falls
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6
Q

what is the adaptive change to hypoxia

A

alkalosis compensated by renal bicarbonate secretion

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7
Q

what is the effect of hyperventilation due to hypoxia

A

increased ,minute ventilation
PaCO2 de creases
alkalosis initially
tachycardia

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8
Q

what are risk factors for acute mountain sickness

A

recent travel ove r2500m
younger people
altitude/ rate of ascent/ previous AMS history

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9
Q

what are the criteria for AMS

A

headache and 1 other symptom, ascend over 2500m

lake louis scare > 3

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10
Q

can you continue ascent with AMS

A

NO!! never go higher

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11
Q

what does HAPE stand for

A

high altitude pulmonary oedema

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12
Q

what are criteria for HAPE

A

unacclimated individual, AMS, cough and shortness of breath, rapid ascent above 8000ft

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13
Q

what reduces risk of HAPE

A

Sleeping below 6000ft

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14
Q

what is the incidence of HAPE at 4000m

A

2%

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15
Q

what is the treatment for HAPE

A

oxygen, decsent, Gamow bag, steroids, calcium blockers

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16
Q

what does HACE stand for

A

high altitude cerebral oedema

17
Q

what are the signs and symptoms of HACE

A

AMS is prerequisite
confusion
behaviour change

18
Q

treatment for HACE

A

immediate descent and symptoms may resolve quickly

Gamov bag can be used to restore pressure

19
Q

what happens to pressure as you descend

A

increases with depth

- every 10m sea water descended, add 1 addition atm (i.e. 20m below = 3atm)

20
Q

what is Henry’s law

A

amount of gas dissolved in a liquid at given temperature is directly proportional to partial pressure

21
Q

what is the relevance of Henry’s law on diving

A

proportionally more gas dissolved in tissue at depth; if ascent at rate that exceeds body’s capacity to clear this excess gas, inert bubbles may form in tissues leading to DCI

22
Q

what is Boyle’s law

A

at constant temperature, the absolute pressure of fixed mass of gas is inversely proportional to its volume
P1V1 = P2V2

23
Q

what are the applications of Boyle’s law

A

barotrauma, arterial gas embolism, gas supplies

24
Q

what are the physiological change of the dive reflex

A

apnoea, bradycardia, peripheral vasoconstriction

25
Q

what is Dalton’s law

A

total pressure extered by mix of gases is equal to sum of pressures that would be exerted by each of the gases if it were alone and occupied the total volume

26
Q

what is the presentation of CNS toxicity

A 
conVENTID;
vision (tunnel)
ears (tinnitus)
nausea
twitching (extremities, facial muscles)
irritability
dizziness
convulsion (often 1st sign)
27
Q

what is pulmonary oxygen toxicity

A

Lorrain-Smith effect; PiO2 > 0.5 ata

- problem in itu patients

28
Q

what is inert gas narcosis

A

most common is nitrogen
worsens with increasing pressure
narcotic potential related to lipid solubility

29
Q

what is decompression ilness

A

N2 poorly soluble, ascent leads to fall in pressure leads to fall in solubility so gas bubbles form

30
Q

what is type I decompression illness

A

cutaneous only

31
Q

what is type II decompression illness

A

neurological

32
Q

what is treatment for decompression illness

A

oxygen, supportive treatment, urgent recompression

33
Q

what is an arterial gas embolism

A

gas enters circulation via torn pulmonary vein
small transpulmonary pressure can lead to AGE
normally occurs within 15 mins of resurfacing

34
Q

what is the treatment of AGE

A

urgent recompression

35
Q

what happens in pulmonary barotrauma

A

air leaks from burst alveoli

36
Q

what are the causes of pulmonary barotrauma

A

pneumothorax
pneumomediastinum
subcutaneous emphysema

Respiratory (11 decks)

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