Measuring a Bronchodilator Response

Question 1

What is BD response?

Answer 1

’ Determination of improvement of airflow in response to BD administration as measured by change in FEV1 and FVC ‘

Question 2

When can it be used?

Answer 2

• With known or suspected airflow obstruction

- Such as Asthma/COPD

Question 3

What do you always need to check before?

Answer 3

• Signed referral form/prescription from requesting clinician
• Local SOP

Question 4

5 key steps of BD response

Answer 4

1. Choice of test (Is it worth doing it based on the baseline tests)
2. Which drug? B2 agonist/Anticholinergic/Corticosteroids
3. Which device? MDI/Extension/Neb
4. Re-test (time interval)
5. Interpretation

Question 5

What indications are there for BD response?

Answer 5

• Determine improvement of airflow obstruction (FEV1/FVC)
• Confirm/Support diagnosis of Asthma or to differentiate between COPD/Asthma
• Evaluate drug regimes
• Post BD FEV1 used for COPD diagnosis
• Determine Prognosis
• Reverse bronchospasm

Question 6

Clinical Features of Asthma/COPD

Answer 6

Refer to Paper Copy

Question 7

Factors influencing BD response

Answer 7

• Severity of Baseline Obstruction
• Type of BD/Dose
• Device used
• Timing of repeat test
• Previous BD used?
• Criteria
• Time of day

Question 8

What patients may be resistant to BD therapy?

Answer 8

• Severe asthmatics may be resistant to BD bc of airway oedema, secretions blocking airways which means slow response to BD

Question 9

A clinician error with BD’s?

Answer 9

• Routinely ordered without checking pre BD results

- increased time and expense

Question 10

Method

Answer 10

• Patients stable and free from infection
• Prior instructions regarding previous BD on the day/yday
• Drug history
• Baseline FEV1/FVC/VC recorded
• Administer BD via device
• Discontinue if patient experiences symptoms/side effects
• Date/Time of each manoevre

Question 11

Guidelines

Answer 11

ATS/ERS

SABA - 400micrograms and between 10-15 minutes wait time in between

Short acting AntiChol

-160 micrograms and 30 minutes wait time in between

Question 12

Contraindications/Cautions

Answer 12

• Known or suspected reactions to a BD
• Spiro Contras
• Pregnancy
• Poor technique

Question 13

Other types of tests which get requested?

Answer 13

• Comparison of 2 different BD’s or via a different device

- 2 seperate days but same time of day and same equipment/physiologist

Question 14

Whats the minimum info needed on the report?

Answer 14

• Baseline (FEV1/FVC/VC)
• Post BD results
• Reference values
• Graphs
• Inhaled drug, dose , device
• Other drugs taken
• Comments

Question 15

Guidelines for Exam REMEMBER!

Answer 15

• > 12% and 200ml in FEV1 and/or FVC (increase)

Question 16

Percentage change

Answer 16

(new-old) / actual value

Question 17

Limitations of BD studies

Answer 17

• Failure to get a significant response
• Responses less than 15% does not rule out asthma
• Technique internet with caution
• Spiro may induce bronchoconstriction

Question 18

Summary?

Answer 18

• Patients with Asthma and COPD may demonstrate significant bronchodilator responsiveness to inhaled BD
• Interpret in line with history, examination, other tests
• Several factors influence responses to BD, e.g.:
  Severity of baseline airflow obstruction
  Drug administered/dose/mode of administration
• Spirometry is commonly used to assess changes in lung function following BD administration
  Measurement of FEV1 and FVC
• Acceptable & reproducible measurements are required
• Relatively quick, inexpensive and readily available
• Appropriate time intervals for measuring BDR are important
• There are several criteria commonly used to evaluate measured responses
  ATS/ERS = > 12% and 200ml increase in FEV1 and/or FVC
• Limitations to bronchodilator assessments