INDIRECT Bct

Question 1

WHY MANNITOL?

Answer 1

Work indirectly to cause bronchoconstriction by releasing mediators from inflammatory cells which act on specific receptors within the airways
•More specific for asthma than direct agents

Question 2

WHAT IS MANNITOL

Answer 2

Capsule containing dry powder, administered via an inhaler device:
oIncreasing doses (total dose = 635mg)
oCannot skip doses
oFEV1 used to monitor response

Question 3

WHAT DOES MANNITOL DO?

Answer 3

Mannitol increases osmolarity of ASL
•Water moves from epithelial cells to restore ASL

Significant bronchoconstriction of bronchial smooth muscle

Question 4

WHAT IS A POSITIVE RESPONSE?

Answer 4

15% fall in FEV1 from baseline FEV1 or

o≥10% incremental fall in FEV1 between doses

Question 5

HOW LONG SHOULD THE TEST BE COMPLETED BY? (?Mins)

Answer 5

35 minutes

Question 6

Advantages for mannitol

Answer 6

Quick
•Standardised procedure
•Reduced need to calibrate equipment
•Storage in refrigerator not required
•Long shelf life / less wastage
•↑ specificity for asthma
•Safer (asthmatic staff)
•More rapid spontaneous recovery in FEV1 post test

Question 7

The limitations are:

Answer 7

Cough
•Not currently used in paediatrics (UK)
•Capsule contains gelatin:
oHypersensitivity of gelatin is an absolute contraindication7

Question 8

How would you classify MANNITOL BHR IN TERMS OF SEVERITY

Answer 8

635- NORMAL
<635->155- MILD BHR
<155- >35MODERATE
<35- SEVERE