L6 Pulmonary Function Testing

Question 1

What are the 4 uses of pulmonary function testing?

Answer 1

1. assessment of breathlessness, asthma and other chronic disorders.
2. Diagnosis of respiratory conditions: airway obstruction, pulmonary vascular disorders, etc
3. Monitoring response to treatment
4. assessing fitness to undergo surgery, fly, scuba dive and to enter certain occupations.

Question 2

What is spirometry and what does it measure?

Answer 2

Uses a spirometer to measure the volume of air inspired and expired by the lungs.
FEV1: forced expiratory volume in 1 second.
FVC: maximum amount of air a person can expel from the lungs after maximum inspiration.
FEV1/FVC provides a measure of the extent of airway limitation. In patients with obstruction, the ratio will be reduced.
Results are compared with reference values matched for age, gender, height and ethnicity.

Question 3

Describe Peak Expiratory Flow (PEF) monitoring.

Answer 3

PEF meter assesses the diurnal variability of airflow obstruction, as well as response to therapy.
PEFR is the maximal flow achieved during maximally forced expiration initiated at full inspiration. Measured in litres per minute.

Question 4

Describe pulmonary function test results that may indicate a person has asthma.

Answer 4

Large rise (>400mL) in FEV1 in response to a short-acting beta-agonist.
Variation in PEF of 20% or greater over a period of days to weeks.
FEV1 or PEF change with a therapeutic trial over a number of weeks.

Question 5

Describe pulse oximeters, including how they work and what they measure.

Answer 5

Measure oxyhaemoglobin saturation. A clip containing light-emitting diodes is attached to the finger or ear lobe. Light absorption by oxyhaemoglobin and reduced haemoglobin are compared to give Sp02. normal values are above 95%.

Question 6

What do arterial blood gas analysers measure? What parameters can be assessed by this?

Answer 6

PaO2, PaCO2 and pH.

Provides info regarding blood oxygenation, acid-base balance and adequacy of ventilation.

Question 7

How many breaths per minute is the normal respiration rate?

Answer 7

12-20 breaths per minute.