Rules Engine

Interpretation Playbook

Back to Overview Case Simulator Open Workstation

Purpose

Show the reading sequence clearly

Use this page when the operator needs to explain why the report reads the way it does.

Primary Use

Spirometry to full PFT flow

Move from quality and ratio to TLC, DLCO, and advanced testing only when needed.

Best Pairing

Keep the workstation open nearby

Review the logic here, then return to live data entry and report completion.

Start with technical acceptability

Before any strong interpretation, the operator should know whether the session grade is acceptable, usable, or limited.

Anchor obstruction at LLN

FEV1/FVC below the lower limit of normal is the entry point for obstruction, not a fixed 0.70 threshold.

Use FVC to decide the next branch

Low FVC with obstruction needs lung volumes. Low FVC with preserved ratio needs TLC review for restriction versus nonspecific pattern.

Read severity from z-scores

Values move from normal to mild, moderate, and severe as the z-score becomes more negative. That is easier to defend than percent predicted alone.

Bronchodilator response stays explicit

The workstation keeps the ATS/ERS percent-of-predicted response rule visible instead of burying it in the report text.

TLC resolves restriction

TLC below LLN supports restriction. Preserved TLC with a low FVC points away from primary restriction and toward nonspecific pattern or obstruction with low FVC.

RV/TLC reveals air trapping

When RV/TLC sits above its upper limit of normal, the report can surface air trapping or hyperinflation explicitly.

DLCO adds physiologic depth

Reduced DLCO below LLN should remain visible as a separate gas transfer impairment, not be flattened into the spirometry label.

FeNO and challenge answer airway biology questions

Use FeNO and bronchial challenge when symptoms or asthma suspicion remain unresolved after baseline spirometry, not as automatic add-ons to every report.

Respiratory muscle tests clarify weakness

SNIP, MIP, and MEP should be interpreted against entered lower limits of normal and used when weakness would change the meaning of low volumes or symptoms.

CPET should stay high-yield

Focus the exercise read on peak VO2, VE/VCO2 slope, breathing reserve, oxygen pulse, desaturation, and effort adequacy rather than the full device printout.

Finish with structured wording

The final impression should still show the logic path: quality, pattern, severity, bronchodilator response, TLC, DLCO, and only the advanced modules that changed the interpretation.

Spirometry Output

Deterministic before narrative

The workstation is designed so the operator can see exactly why "obstructive," "low FVC with preserved ratio," or "no primary spirometric abnormality" was selected.

Input	Interpretive Use
FEV1/FVC vs LLN	Obstruction gate
FVC vs LLN	Low-volume branch
FEV1 z-score	Severity ladder
Pre/post values	Bronchodilator response

Full PFT Output

Pattern resolution and advanced testing layer

The F3 branch keeps restriction, air trapping, reduced gas transfer, airway biology, muscle weakness, and exercise limitation explicit so the operator can carry only the useful findings into the final report.

Input	Interpretive Use
TLC vs LLN	Restriction confirmation
RV/TLC vs ULN	Air trapping / hyperinflation
DLCO vs LLN	Gas transfer impairment
DLCO z-score	Severity wording
FeNO band	Type 2 airway inflammation signal
PD20 / PD15 or key FEV1 fall	Challenge positivity threshold
SNIP / MIP / MEP vs LLN	Respiratory muscle weakness
Peak VO2, VE/VCO2, breathing reserve	CPET limitation pattern

Guideline Use

Use the advanced modules selectively

FeNO follows ATS adult cut-points, challenge testing follows ERS threshold-based interpretation, respiratory muscle testing follows LLN-based reading, and CPET stays limited to variables that change the limitation pattern.

Teaching Cases

Examples now mirror the workstation

The logic page now lines up with the teaching cases for high FeNO with positive challenge, respiratory muscle weakness, CPET deconditioning, and CPET ventilatory limitation.