Respiration

Question 1

Explain tidal volume and state the normal value.

Answer 1

Volume inspired in and out with normal breathing.

500mL.

Question 2

Explain inspiratory reserve volume and state the normal value.

Answer 2

The difference in volume between TV and maximal inspiratory effort. 2-3L.

Question 3

Explain expiratory reserve volume and state the normal value.

Answer 3

The difference in volume between TV and maximal expiratory effort. 1L.

Question 4

Explain residual volume and state the normal value.

Answer 4

The volume of air left in the lung AFTER maximal expiratory effort. 1L (cannot be measured by spirometry).

Question 5

Explain inspiratory capacity and state the normal value.

Answer 5

TV + IRV. 2.5-4L.

Question 6

Explain functional reserve capacity and state the normal value.

Answer 6

ERV + RV = 2L.

Question 7

Explain vital capacity and state the normal value.

Answer 7

IRV + TV + ERV = 3 - 4.5L.

Question 8

Explain total lung capacity and state the normal value.

Answer 8

IRV + TV + ERV + RV = 4-6L.

Question 9

Explain anatomic and physiologic dead space and state the normal volumes.

Answer 9

i) Anatomic: conducting airways that do not participate in gas exchange (150mL).
ii) Physiologic: volume of TV that does not partake in gas exchange (150mL, higher in the case of lung disease).

Dead space: 300mL.

Question 10

Explain what FEV1.0 means and state average values.

Answer 10

Forced Expiratory Volume: volume of air that can be expired within one second after maximal inspiration. Expressed as FEV/FVC (forced vital capacity.
Normal: 0.8 (80%)
Restrictive Lung Disease: >/= 0.8 (80%, reduce FEV and FVC)
Obstructive Lung Disease: <0.8 (80%).

Question 11

Describe the staging process of lung disease.

Answer 11

O (At Risk) - Normal spirometry, but has RFs.
**ALL BELOW HAVE FEV1/FVC OF <70%**
I (Mild) -  FEV1 at least 80% predicted
II (Moderate) - FEV1 50% - 80% predicted
III (Severe) - FEV1 30% - 50% predicted
IV (Very Severe) - FEV1 <30% predicted.

Question 12

Describe the significance of FEV3.0 and state the normal values.

Answer 12

Measures air flow in the small airways so can provide info about smoking damage. This will also be impacted FIRST. Should be >90%.

Question 13

Describe what Maximum Voluntary Volume is and its significance.

Answer 13

Pt breathes as hard and fast as they can for 12s (X5 for L/min). MVV - v indicated capacity for exercise, ensures that thay have reserve.

Question 14

What is DLCO and how can it be affected?

Answer 14

Diffusion capacity at the blood/gas barrier - it is reduced in the case of:

i) scarring
ii) secretions
iii) COPD (reduced SA)

Question 15

Describe the A-a gradient and state the normal values.

Answer 15

Difference between alveolar and arterial pressure. Normally <10mmHg.
Note: if low DLCO, A-a gradient will be higher.