Service manual

IQmark Digital Spirometer Operation Manual
67
E. Interpretation – ATS
The American Thoracic Society (ATS) created recommendations for the interpretation of
Spirometry tests. Measurements are compared to the Lower Limit of Normal (LLN).
The IQmark Digital Spirometer software displays the statement "Normal Spirometry" if
the FVC and the FEV1/FVC ratio are within the normal range (i.e., above the LLN).
Airway Obstruction - If the FEV1/FVC ratio is below the LLN, the software displays
one of the following statements regarding obstruction.
Statement Criteria
Obstruction may be a
physiological variant. FEV1 >= 100% Pred. FEV1
Mild obstruction. 70% Pred. FEV1 <= FEV1 < 100% Pred. FEV1
Moderate obstruction. 60% Pred. FEV1 <= FEV1 < 70% Pred. FEV1
Moderately severe obstruction. 50% Pred. FEV1 <= FEV1 < 60% Pred. FEV1
Severe obstruction. 34% Pred. FEV1 <= FEV1 < 50% Pred. FEV1
Very severe obstruction. FEV1 < 34% Pred. FEV1
If the FVC is below the LLN, the software will add, "with low vital capacity" to the above
obstruction statements.
Lung Restriction - If there is no suggested airway obstruction, the program displays one
of the following statements pertaining to lung restriction.
Statement Criteria
Mild restriction. 70% Pred. FVC <= FVC < LLN
Moderate restriction. 60% Pred. FVC <= FVC < 70% Pred. FVC
Moderately severe restriction. 50% Pred. FVC <= FVC < 60% Pred. FVC
Severe restriction. 34% Pred. FVC <= FVC < 50% Pred. FVC
Very severe restriction. FVC < 34% Pred. FVC
Pre/Post Bronchodilator Comparison - If both pre and post bronchodilator tests have
been performed, the software performs and reports automatic interpretation for both sets
of test data.
Statement Ratio of Post-BD / Pre-BD (Post/Pre)
Post FVC/Pre FVC Or Post FEV1/Pre FEV1
Markedly improved >= 1.25 >= 1.25
Improved 1.15 to 1.24 1.12 to 1.24
Not clearly improved 1.05 to 1.14 1.05 to 1.11
Not improved < 1.05 < 1.05
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