Ventilation

Question 1

Standard Atmospheric Pressure?

Answer 1

760 mm Hg

Question 2

Is pleural or pulmonary pressure lower?

Answer 2

Pleural pressure is lower

Question 3

Normal FEV1/FVC?

Answer 3

80%

Question 4

Effect on FEV1 and FEV1/FVC during OBSTRUCTIVE airway diseases?

Answer 4

Reduced

Question 5

Obstructive vs Restrictive in definition?

Answer 5

Obstructive: obstruction within airway affecting airflow
Restrictive: problem outside the airway affecting elastic work

Question 6

Residual volume in obstructive disease?

Answer 6

Higher (since didn’t release more volume)

Question 7

Effect on FEV1 and FEV1/FVC during RESTRICTIVE airway diseases?

Answer 7

Reduced FEV1, but normal FEV1/FVC

Question 8

Technique used to measure Functional Residual Volume (FRC)

Answer 8

Helium Dilution technique: known volume of 10% Helium, and when person breathes after full expiration start breathing into spirometer

Question 9

What 3 things can spirometer not measure?

Answer 9

FRC, TLC, RV

Question 10

3 types of dead space?

Answer 10

1. Anatomical
2. Alveolar
3. Physiological

Question 11

Anatomcial dead space?

Answer 11

350ml out of total 500ml (tidal volume) enters alveoli.

150ml remaining in mouth/nose/pharynx/trachea = anatomical dead space

Question 12

Alveolar dead space?

Answer 12

Air in alveoli that is surrounded by pulmonary capillaries with no blood flow

Question 13

Physiological dead space?

Answer 13

Anatomical + Alveolar dead space

Question 14

Fowler’s method?

Answer 14

Used to measure anatomical dead space:
- continuous nitrogen exhaled measures
Phase 1: no nitrogen
Phase 2: rapid rise in N2
Phase 3: plateau
(issue: mixture of alveolar + anatomical)

Question 15

Bohr’s method?

Answer 15

Used to measure physiological dead space: PaCO2 of alveoli (arterial blood) and expired air

Question 16

Pulmonary ventilation is always (in normal person)

Answer 16

6000ml/min

Question 17

Normal alveolar ventilation

Answer 17

4200ml/min

Question 18

Optimum rate of ventilation?

Answer 18

15 breaths/min

Question 19

Optimum tidal volume?

Answer 19

500ml

Question 20

Total lung elasticity made up 1/3 and 2/3 what?

Answer 20

1/3 tissue elastic forces

2/3 fluid air tension elastic forces in alveoli

Question 21

Function of surfactant other than reducing surface tension and increasing compliance?

Answer 21

Stabilising alveoli of different sizes