Lung physiology 2

Question 1

TLC

Answer 1

Total lung capacity

Question 2

FEV1

Answer 2

Forced expiratory volume in one second

Question 3

FVC

Answer 3

Forced vital capacity

Question 4

PEF

Answer 4

Peak expiratory flow

Question 5

FEF25

Answer 5

Flow at point where 25% of total volume to be exhaled has been exhaled

Question 6

Lung volume - gas dilution

Answer 6

Measurement of all air in the lungs that communicates with the airways.
Does not measure air in non-communicating bullae.
Either closed circuit helium dilution or open circuit nitrogen washout.

Question 7

Total body plethysmography

Answer 7

Measures all lung volume.
Includes the patient panting in a box which creates a pressure proportional to the volume of air in the chest.

Question 8

Carbon monoxide

Answer 8

Used to estimate TLco
This is the overall measure of interaction of:
alveolar surface area
alveolar capillary perfusion
physical properties of the alveolar capillary interface
capillary volume
haemoglobin concentration, and the reaction rate of carbon monoxide and hemoglobin.

Question 9

Forced vital capacity - predicted

Answer 9

A value of 80% or greater - ‘normal’
Low value = airway restriction

Question 10

FEV1 / FVC ratio

Answer 10

A ratio of less than 0.7 indicates airway obstruction.