FVC Tracing: FEVt and FEVt% Calculator

Calculates FEVt% from a timed FEV reading and FVC reading from a tracing.

Inputs

Color mode links each input to the matching equation term and solving arithmetic.

Equation and Work

Equation:
Solving steps:
FEVt%
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%
FEVt
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L
Reference status
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Normal/reference: FEV0.5% 50–60%; FEV1% 75–85%; FEV2% 94%; FEV3% 97%. FEV1% of 65% or less is clinically significant for airflow obstruction in the book discussion.

Clinical Significance

FEVt% compares forced expiratory volume at a selected time to FVC. The constant 100 converts the ratio into percent.

Timed FEV ratios help distinguish obstructive and restrictive ventilatory patterns when interpreted with predicted values and clinical context.

Graph reading and patient effort affect results. Use predicted values matched to patient demographics for formal interpretation.

References (APA 7th Edition)

  1. Chang, D. W. (2020). Respiratory Care Calculations (Revised 4th ed.). Jones & Bartlett Learning. Formula content adapted from the uploaded text/reference packet.