Lungs in the wild environment

Question 1

What does boyles law state?

Answer 1

At a constant temperature the absolute pressure of a fixed mass of gas is inversely proportional to its volume

P1V1=P2V2

Question 2

What is an arterial gas embolism?

Answer 2

Gas enters circulation via torn pulmonary veins

Small transpulmonary pressures can lead to AGE

Normally occur within 15 minutes of surfacing

Urgent recompression needed

Question 3

What is apnoea?

Answer 3

pause in breathing

Question 4

What is pulmonary oxygen toxicity?

Answer 4

If PiO2 > 0.5 ATA (atmospheric absolute)
100% oxygen leads to symptoms in 12 - 24 hours

Cough, chest tightness, chest pain, shortness
of breath

Also a problem with ITU patients

Question 5

Normal physiological response to ascent:

Answer 5

Hypoxia leads to..

Hyperventilation at 10000ft altitude
Increases minute ventilation
Lowers PaCO2
Alkalosis initially
Tachycardia

Ascending; PiO2 falls (FiO2 remains constant)
Decreased PAO2
Decreased PaO2
Peripheral chemoreceptors fire (e.g. carotid body)
Activates increased ventilation (VA), reducing PaCO2
Increased PAO2
Increased PaO2

Question 6

Name 3 high altitude ilnesses

Answer 6

Acute Mountain Sickness
High Altitude Pulmonary oEdema (HAPE)
High Altitude Cerebral Oedema (HACE)

Question 7

Acute mountain sickness

Answer 7

Recent ascent to over 2500m
Lake Louise score > 3
Must have a headache and one other symptom

Treatment is to descend

Question 8

High Altitude Pulmonary Oedema

Answer 8

Unacclimatised individuals
Cough, shortness of breath
Rapid ascent above 8000ft (2438m), more common in excercise
2-5 days

Treatments:
O2
Decent urgent
Gamow bag
Steroids
Ca2+ blockers?
Sildenafil

Question 9

Effect of flying on the lungs:

Answer 9

Reduced ambient pressure which reduces PiO2 and thus PAO2 and thus PaO2

High A-aO2 may also contribute to patient hypoxia if they have significant lung disease

Question 10

What is pressure at 150m?

Answer 10

pressure at surface (0m) is 1atm, then for every 10 m add 1

at 150m it’s 16atm

Question 11

shallow water blackout

Answer 11

PaO2, PaN2, PaCO2 rise

Eventually CO2 builds up sufficiently to induce desire to breathe
Diver returns to surface
PaO2 falls, PaCO2 rises

Question 12

What is decompression sickness?

Answer 12

N2 forced into tissue e.g. spinal cord, brain, organs etc. As diver rises volume of bubbles rises (pressure decreasing)

Question 13

High Altitude Cerebral Oedema (HACE)