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Happy New Year Everyone!
We are reviewing contraindications for mannitol challenges (the latest Aridol PI is attached for reference).
We’re interested in how others interpret the sentence:
“General precautions when conducting spirometry and bronchial provocation testing should be
observed, including using caution in patients with the following: ventilatory impairment
(resting FEV1 of less than 70% of normal predicted values or an absolute value of 1.5L in
adults)”For adults, does your lab interpret “ventilatory impairment (resting FEV1 of less than 70% of normal predicted values or an absolute value of 1.5L in
Adults)” as:
1) If either of these conditions are met – contraindication to test?
2) Only where ventilatory impairment is observed – if either of these conditions are met – contraindication to test; e.g. in a small adult (e.g. older female, 150cm) where baseline spirometry is within normal limits but FEV1 is 1.40L (and >70% pred) is it ok to proceed with mannitol? If yes – what absolute value of FEV1 do you consider a contraindication to test and why?
3) Still do mannitol challenge, but proceed with caution?
4) something else? If so, please advise.We also note that in the test instructions https://www.aridol.info/test-instructions – only FEV1>70% Pred is mentioned…
Thank you in anticipation of your response.
Best wishes,
Brigitte
Dear Brigitte,
Thank you for raising this. We follow an approach most consistent with option 2, but we don’t apply a strict numerical cutoff when deciding whether to proceed with a mannitol challenge. If a patient’s baseline FEV₁ is <1.5 L or <70% predicted, we review the case individually rather than treating it as an automatic contraindication.
We take into consideration the patient’s age, duration and stability of their asthma, previous lung function, and current medication use. This helps us determine whether a low FEV₁ represents true ventilatory impairment or simply reflects normal physiology in a smaller adult. It also helps us to determine how well the patient is likely to recover with Ventolin if they experience a fall in FEV₁ during the challenge.
Aside from the safety concerns, there is the potential for interpretation uncertainty in patients with reduced baseline airway calibre. A low starting FEV₁ increases the likelihood of an exaggerated or false‑positive response, and for that reason, we will not proceed if we feel the baseline FEV₁ is too low to allow a reliable or safe test outcome.
Best wishes, Kate
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