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Formulae Sheet

Formulae Sheet


  1. Fev1 as a percentage of predicted

    • ( Meas Fev1 ÷ Pred FEV1 ) x 100 = % predicted

  2. FEV as a percentage of predicted

    • ( Meas FVC ÷ Pred FVC ) x 100 = % predicted

  3. Fev1/FVC Ratio

    • ( Meas Fev1 ÷ Meas FVC ) x 100

  4. To measure reversibility to bronchodilators expressed as change in Fev1 in mls

    1. Post Fev1 - Pre Fev1 x 1000 to give mls
    2. E.g. 1.6 – 1.2 = 0.4 litres x 1000 = 400mls


* See Note Below

Normal

Obstruction

Restriction

Combined

Fev1

>80%







FVC

>80%

>80%





Fev1/FVC

>70%



>70%




* Very Mild Obstruction may be seen with an FEV1 & FVC >80% but the ratio would be < 70%