Basic Cardio Terms

Question 1

Compliance

Answer 1

change in volume/ change in pressure. This is the ability of the lungs distend and how much work of breathing is required to expand the lungs
the lungs are least compliant at extremes of volumes, when the lungs are stiff, closed alveoli or hyper inflated

Question 2

Airflow resistance

Answer 2

caused by friction which is caused in the airways when gas slides against the walls
depends on speed of airflow and calibre of the airway

Question 3

When is compliance decreased and resistance increased?

Answer 3

secretions where there is greater overall resistance and less collateral ventlation
bronchospasm
odema
collapsing of the airways with emphysema
Kyphoscolisosis or distended abdomen reduce compliance

Question 4

Elastic resistance

Answer 4

lung tissue, alveolar surface liquid and the chest wall

this is increased by lung fibrosis, pulmonary oedema, rib cage deformity, obesity, slumped

Question 5

Work of breathing

Answer 5

during inspiration to overcome the resistive elastic forces of airways, lungs and chest wall

Question 6

Ventilation

Answer 6

Most of the tidal volume typically goes to the dependent part.

Question 7

Upright position

Answer 7

Tidal volume goes to the inflated areas of alveoli which are the non dependent parts and they are rapidly filled. Gas then travels to the dependent areas. Dependent areas compressed by weight of lungs, blood supply so have more potential to expand and more compliant so allow greater ventilation.

Question 8

Slumped positioning

Answer 8

alveoli collapsed or compressed, lower on the compliance curve and less easy to inflate

Question 9

Side lying

Answer 9

lower lung provides a greater contribution to gas exchange which is why the good lung is put on the bottom
the upper lung however is more expanded and therefore responds earlier to deep breathing exercises.

Question 10

Increased closing volume

Answer 10

smoking

ageing- reduced elasticity

Question 11

What is perfusion effected by?

Answer 11

lung volume- vessels being hyper-inflated
disease- alveolar destruction
position- prone is better

Question 12

VQ matching

Answer 12

fresh air and blood need to be in the same place for gas exchange to occur
high ratio- alveoli is ventilated by perfusion is impaired so oxygen can’t reach the blood, causing an increase in dead space, e.g heart failure causes breathlessness
low ratio- lung units perfused but not adequately ventilated , creating a shunt

Question 13

Shunt

Answer 13

fraction of cardiac output not exposed to gas exchange in the lung

Question 14

systematic hypoxia

Answer 14

stimulates selective vasodilation to assist perfusion of vital tissues

Question 15

pulmonary hypoxia

Answer 15

stimulates hypoxic vasoconstriction which maintains gas exchange by constricting capillaries, limiting wasted perfusion