Lung Function Testing

Question 1

What is peak flow?

Answer 1

Measures fastest rate of air blown out of lungs in L/min, can be used in diagnosis and monitoring of asthma. Dependant on height, age, gender.

Question 2

How would you record peak flow?

Answer 2

1) ID, informed consent
2) Decontaminate hands
3) Patient standing/ sitting upright
4) Insert disposable mouthpiece with a one-way valve into peak flow meter, use appropriate size mouthpiece
5) Set pointer on meter to 0, ask patient to hold meter underneath
6) Take full breath in, seal mouth around mouthpiece and blow hard/fast over 1/2 seconds
7) Ensure remains upright (not leaning forward) when blowing
8) Repeat x3 and record best reading
9) Document if patient unable to. Document measurement, report any low readings

Question 3

What is spirometry?

Answer 3

Measures how quickly and effectively lungs can be emptied and filled

Question 4

What measurements can spirometry take?

Answer 4

• Forced expiratory volume in 1 sec (FEV1)
• Forced vital capacity (FVC)
• FEV1/FVC - low value = narrowed airways
• Degree of reversibility following administration of bronchodilator

Question 5

What do the following spirometry results categorise COPD as?

FEV1 At least 80% of predicted value

Answer 5

Mild (stage 1)

Question 6

What do the following spirometry results categorise COPD as?

FEV1 50 - 79% of predicted value

Answer 6

Moderate (stage 2)

Question 7

What do the following spirometry results categorise COPD as?

FEV1 30 - 49% of predicted value

Answer 7

Severe (stage 3)

Question 8

What do the following spirometry results categorise COPD as?

FEV1

Answer 8

Very severe (stage 4)

Question 9

What would you advise patient not to do prior to performing spirometry?

Answer 9

• Smoke for 24hrs
• Heavy meal 2hrs
• Alcohol 4hrs
• Vigorous exercise 30mins
• No restrictive clothing
  Document any deviations

Question 10

How would you perform spirometry? (preparation)

Answer 10

1) ID, informed consent
2) Decontaminate hands
3) No contradictions
4) Empty bladder
5) Age, gender, height recorded
6) Seated in chair with arms, feet flat on floor
7) Losen tight clothing, remove false teeth if loose fitting

Question 11

What are some contradictions to spirometry?

Answer 11

• Previous problems
• Current acute illness
• Coughing up blood
• Suspected/active TB
• Unstable heart disease/angina
• Recent pneumothorax (3mnths)
• Recent eye surgery
• Recent abdominal/chest surgery (3 mnths)
• Diagnosed aneurysm
• Ear problems, fainting history, glaucoma, pregnant

Question 12

How would you perform spirometry? (slow VC)

Answer 12

Done first

1) Nose clip on/ hold nose, breathe in deeply as poss
2) Place lips around mouthpiece to form seal, blow out slowly and steadily for as long as poss
3) Repeat x2 to ensure results consistent, accurate

Question 13

How would you perform spirometry? (forced VC)

Answer 13

1) Remove nose clip
2) Ask to blow out forcibly and rapidly for as long as poss until no breath left (6-15secs), take min of 3 readings (best 2 should have FVC within 100mls of each other)
3) Should not lean forwards when breathing out
4) Should not cough/take another breath during procedure
5) Record:
- FEV1 and % of predicted FEV1
- FVC and % of predicted FVC
- Peak flow (PEF)
- FEV1/FVC

Question 14

How would you perform spirometry? (reversibility testing)

Answer 14

Only done if doubt over diagnosis and to ID asthma

1) Patient prescribed bronchodilator (usually salbutamol)
2) Measure FEV1
3) Patient take 4 puffs of inhaler via large volume spacer
4) After 20 mins, remeasure FEV1, if increase of >12% from baseline reading, indicate reversible airflow obstruction and supports asthma diagnosis