Ventilation

Question 1

What is Pulmonary ventilation?

Answer 1

The volume of air inhaled per minute (minute ventilation/ (VE) )

Question 2

What is Alveolar ventilation?

Answer 2

The volume of air reaching the respiratory zone per minute

Subtract physiological dead space from tidal volume

Question 3

What are the four lung volumes?

Answer 3

Inspiratory reserve volume
Tidal volume
Expiratory reserve volume
Residual volume

(no overlap)

Question 4

What are the four lung capacities?

Answer 4

Inspiratory capacity (tidal + Inspiratory reserve)

Vital Capacity (all but residual volume)

Functional residual capacity (Residual volume + Expiratory reserve volume)

Total lung capacity

Question 5

What are the factors affecting lung volumes and capacities?

Answer 5

Body size (height and shape - but obesity does not increase size of lungs), sex (males larger), disease (lung muscle/tissue disorders), age (decrease with age), fitness (innate&raquo_space; training)

Question 6

How do rate of exhalation and Forced Vital capacity change in restrictive airway disease?

Answer 6

Normal rate of exhalation

Reduced FVC

Question 7

What is FVC?

Answer 7

Forced vital capacity

Question 8

How do rate of exhalation and Forced Vital capacity change in obstructive airway disease?

Answer 8

Reduced rate of exhalation

Markedly reduced FVC

Question 9

How do lung volumes change in Obstructive disease?

Answer 9

Increased residual volume, with reduced IRV, ERV and TV

Question 10

How do lung volumes change in Restrictive disease?

Answer 10

Decreased IRV, ERV, RV and TV

Question 11

Name two obstructive lung diseases:

Answer 11

COPD and Asthma

Question 12

Name four restrictive lung diseases:

Answer 12

Lung fibrosis, Interstitial lung disease, obesity and neuromuscular disease

Question 13

What is anatomical dead space?

Answer 13

Capacity of the airways incapable of undertaking gas exchange; usually the conducting zone - the first 16 generations of airways (150ml) - e.g. Nose, pharynx, larynx, trachea, bronchi and bronchioles

Question 14

What is Alveolar dead space?

Answer 14

Capacity of the airways that should be able to undertake gas exchange but cannot (e.g. hypoperfused alveoli); usually the non-perfused parenchyma, which should be 0ml in adults

Question 15

What is physiological dead space?

Answer 15

Sum of the alveolar and anatomical dead space; i.e. Should be 150ml in adults

Question 16

What can increase and decrease dead space?

Answer 16

Increase: snorkelling / anaesthetic circuits

Decrease: tracheostomy / cricothyrotomy

Question 17

Describe the Ventilation and perfusion in the lung apex:

Answer 17

Alveoli are stretched by gravity due to a greater transmural pressure, so need a greater pressure to inflate (less compliant and perform less ventilation); simultaneously, blood is pulled downwards, achieving a lower intravascular pressure, causing reduced perfusion

Question 18

Describe the Ventilation and Perfusion in the lung base:

Answer 18

Alveoli are squashed and so can inflate more, performing more ventilation; simultaneously blood is pulled downwards to produce a higher intravascular pressure, increasing perfusion of the parenchyma

Question 19

What is Ventilation Perfusion Matching?

Answer 19

Perfusion and Ventilation both increase towards lung base, but perfusion does so at a greater rate

Question 20

What is wasted ventilation?

Answer 20

Occurs at lung apex bc perfusion cannot meet demands of ventilation supplied

Question 21

What is wasted perfusion?

Answer 21

Ocurs at base bc ventilation cannot meet demands of perfusion supplied

Question 22

What is the Ventilation-Perfusion ratio?

Answer 22

V/Q ratio would be 1 if matched, but gravity means changes regionally (calculated as alveolar ventilation/cardiac output) - averages approx. 0.84 in a healthy lung