Dr Sumit MandalEmergency Medicine
Respiratory

Pulmonary Function Test Interpreter

Calculate predicted spirometry values, enter actual results to classify obstructive, restrictive, or mixed patterns with severity grading. Includes flow-volume loop pattern recognition and interpretation guide.

Step 1 — Patient Demographics

Step 2 — Enter Actual (Measured) Values

FEV1 and FVC are required. TLC helps differentiate true restriction from pseudo-restriction. PEF is optional.

Flow-Volume Loop Patterns

VolumeFlow

Normal

Sharp peak, smooth descent

Obstructive

Scooped/concave expiratory limb

Restrictive

Normal shape but reduced volumes

Fixed UAO

Flattened exp + insp (box shape)

PFT Interpretation Algorithm

FEV1/FVC Ratio< 0.70OBSTRUCTIVE≥ 0.70Check FVCSeverity by FEV1 % predicted (GOLD)Mild≥80%Moderate50–79%Severe30–49%V.Severe<30%< 80%≥ 80%Check TLCNORMAL< 80%≥ 80%RESTRICTIVEPseudo-restrictionIf TLC also low:MIXED PATTERNBronchodilator ReversibilityPositive if FEV1 improves ≥ 12% AND ≥ 200mlSuggests asthma over COPD

Predicted values are reference equations and may vary by ethnicity. Clinical interpretation must consider patient history, symptoms, bronchodilator response, and serial trends. This tool is for educational purposes only.