Mid Topic Review

Question 1

What is decompression illness?

Answer 1

Associated with Nitrogen accumulation in the body

Question 2

What happens when divers go down?

Answer 2

Ambient pressure increases
Pressure in lungs increased
Oxygen and Nitrogen dissolves into tissues

Question 3

Why is there increased dissolving of gas at depth?

Answer 3

Henry’s Law
at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the PARTIAL PRESSURE of that gas in equilibrium with that liquid

Question 4

What are the consequences of too much oxygen?

Answer 4

Oxygen toxicity
Only occurs if Oxygen pressure is above 1.6
Normal atmospheric is 0.2
Would have to be at depths greater than 60m
Deep divers change percentage of oxygen
Prevents as seizures

Question 5

How the effects of gas pressure in diving be mitigated?

Answer 5

Change ambient pressure

Question 6

What are the consequences of too much nitrogen?

Answer 6

Nitrogen narcosis

Drowsiness and confusion

Question 7

What happens if a diver ascends too quickly?

Answer 7

Nitrogen bubbles in your tissues
Rapid decompression
Bubbles compress in nerves - neurological symptoms
Bubbles form in joint

Question 8

What happens to bubbles that enter venous blood?

Answer 8

Get trapped in pulmonary circulation

Question 9

What are the functions of the pulmonary circulation?

Answer 9

Gas exchange
Metabolism of vasoactive substances
Autonomic regulation of blood flow
Local oxygen storage

Question 10

What are the features of metabolism of vasoactive substances?

Answer 10

Primary site of degradation and regulation of vasoactive substances

Huge surface area with very slow moving blood

Endothelial cells have a high concentration of ACE

Question 11

What are emboli?

Answer 11

‘mass’ within the circulation capable of causing obstruction

Question 12

How might air bubbles reach arterial circulation?

Answer 12

Patent foramen ovale

Ventricular septal defects

Question 13

What is PFO?

Answer 13

Patent foramen ovale
a hole in the heart that didn’t close the way it should after birth
allows blood to bypass the pulmonary filter

Question 14

How common are PFO’s?

Answer 14

25% of general population

Question 15

What are the features of ASD’s and VDS’?

Answer 15

VSD’s are more common
Risk of them is that hole can lead to a left to right shunt
Blood gets pushed round the pulmonary circulation again
Puts excess pressure on the pulmonary system
Might experience hypertrophy

Question 16

How might babies with congenital heart defects present?

Answer 16

Breathless
Fatigued
Non-feeding behaviour
Tachycardia

Question 17

How are congenital heart diseases diagnoses?

Answer 17

Echocardiogram

Question 18

What are those with PFO’s at risk of?

Answer 18

Arterial gas embolism - diving

Fatal sequelae: myocardial infarction, stroke, pulmonary embolism