Lungs at depth

Question 1

Who invented scuba diving regulator?

Answer 1

• 1942-43
• Jacques-Yves Cousteau redesigned a car regulator that would automatically provide compressed air to a diver on his slightest intake of breath
• The Aqua Lung was born

Question 2

What is 1 atmosphere pressure equivalent to?

Answer 2

• 10 metres of sea water (33.08 feet)
• 101.3 kilopascals (kPa)
• 14psi

Question 3

What is Boyle’s law?

Answer 3

• At a constant temperature the absolute pressure of a fixed mass of gas is inversely proportional to its volume
• P1V1=P2V2

Question 4

What are the challenges with diving?

Answer 4

• Hazardous
• Physically challenging
• Distortion / impairment of special senses
• General and specific sources of emotional stress
• Claustrophobia, agoraphobia, marine animals
• Hyperbaric environments, cold

Question 5

What is apnoea diving?

Answer 5

• Diver inhales, pre hyperventilation, diver descends holding breath, gas compress.
• Standard diving in a pool along the surface or stationary
• PaO2, PaN2, PaCO2 rise
• eventually CO2 builds up to induce desire to breathe

Question 6

What is the diving reflex?

Answer 6

• Apnoea (temporary cessation in breathing)
• Bradycardia (heart beats really slowly)
• Peripheral vasoconstriction

Question 7

What is Dalton’s Law?

Answer 7

• Total pressure exerted by a mixture of gases is equal to the sum of the pressures that would be exerted by each of the gases if it alone were present and occupied the total volume

Question 8

What are the effects of Dalton’s Law at sea level?

Answer 8

• At sea level;
  partial pressure N2 = 0.78 ata, O2 = 0.209 ata
• At 10 msw;
  partial pressure N2 = 1.56 ata, O2 = 0.418 ata
• Breathing air at 10 msw is same as 42% O2 at sea level)

Question 9

What is the Lorrain Smith effect?

Answer 9

Describes pulmonary oxygen toxicity
When your PiO2 is too high
- Cough, chest tightness, chest pain, shortness
of breath
- Also a problem with ITU patients

Question 10

What is CNS Oxygen toxicity acronym?

Answer 10

V - Vision (tunnel vision etc)
E - Ears (tinnitus)
N - Nausea
T - Twitching (extremities or facial muscles)
I - Irritability
D - Dizziness

Common final (and often the first) sign will be a convulsion
ConVENTID

Question 11

What is Inert Gas Narcosis?

Answer 11

• Commonest is nitrogen narcosis
• Worsens with increasing pressure
• First noticed between 30-40 msw
• Increased PiN2
• Influencing factors- cold, anxiety, fatigue, drugs, alcohol and some medications
• Can end in death

Question 12

What are some symptoms of Inert Gas Narcosis?

Answer 12

• Mild impairment of performance
• Over confidence, sense of well being
• Sleepiness, confusion, dizziness
• Loss of memory, stupefaction
• Unconsciousness, death

Question 13

What is Decompression illness (DCI)?

Answer 13

N2 poorly soluble
- Fall in pressure
- Fall in solubility
- Gas bubbles

Question 14

What are the two types of Decompression illness (DCI)?

Answer 14

Type 1: Cutaneous only
Type 2: Neurologic
O2 supportive treatments and urgent recompression

Question 15

What is an Arterial Gas Embolism?

Answer 15

• Gas enters circulation via torn pulmonary veins
• Small transpulmonary pressures can lead to AGE
• Normally occur within 15 minutes of surfacing
• Urgent recompression
• As a result of a panicking breath hold

Question 16

What is Pulmonary barotrauma?

Answer 16

Air leaks from burst alveoli:
- Pneumothorax
- Pneumomediastinum
- Subcutaneous emphysema