Specialty Hub
Pulmonary Function Testing
Reading the breath as a number. Pulmonary function testing turns how a patient breathes into the values that name a disease — the spirometry ratio that finds obstruction, the lung volumes that confirm restriction, the loop shapes, and the diffusing capacity that points to the cause. This hub teaches the test and how to read it.
Guides
From the spirometry maneuver to reading the loop, the volumes, and the diffusing capacity.
Spirometry Basics
The foundation of pulmonary function testing - what FEV₁, FVC, and the FEV₁/FVC ratio measure, how a good effort is coached and judged (ATS/ERS acceptability and repeatability), and how the ratio separates an obstructive from a restrictive pattern.
Interpreting Pulmonary Function Tests
A systematic way to read a PFT - start with the FEV₁/FVC ratio to find obstruction, use the FVC and TLC to find restriction, grade severity by percent predicted, check bronchodilator response, and let DLCO narrow the cause.
Flow-Volume Loops
Reading the spirometry loop at a glance - the normal shape, the scooped expiratory limb of obstruction, the tall narrow loop of restriction, and the flattened plateaus that flag fixed and variable upper-airway obstruction.
Diffusing Capacity (DLCO)
How well gas crosses the alveolar-capillary membrane - what the single-breath DLCO measures, why carbon monoxide is used, the diseases that lower it (emphysema, interstitial disease, pulmonary vascular disease, anemia) and raise it, and the hemoglobin correction.
Bronchoprovocation & Bronchodilator Response
Proving airway reactivity when spirometry is normal - the bronchodilator reversibility criteria (12% and 200 mL), the methacholine challenge and its PC20, the role of exercise challenge, and how these tests confirm or exclude asthma.
Interactive Practice
Practice Tools
Drill obstructive-vs-restrictive pattern recognition, quantify bronchodilator reversibility against the published threshold, and work the gas-exchange math behind every PFT.
Clinical References
The interpretation cutoffs and the lung-volume measurement methods, ready to scan.
PFT Interpretation Reference
A bedside lookup for reading pulmonary function tests - the obstruction and restriction defining patterns, the FEV₁ percent-predicted severity bands, the bronchodilator reversibility criteria, and the DLCO grading - in one scannable reference.
Lung Volume Measurement Methods
How the lung volumes spirometry can't reach are measured - body plethysmography, helium dilution, and nitrogen washout for FRC, RV, and TLC - with what each method captures, its principle, and where it falls short.
Quick Charts
The loop patterns and the pattern-plus-DLCO diagnosis, side by side.
Flow-Volume Loop Patterns
The flow-volume loop shapes side by side - normal, obstructive, restrictive, and the fixed and variable upper-airway obstructions - with the loop appearance, the hallmark, and the typical cause for each.
DLCO Interpretation
Combining the spirometry pattern with DLCO to name the disease - obstruction or restriction paired with a low, normal, or high diffusing capacity - with the diagnosis each combination points to and why.
Suggested Learning Path
From the spirometry maneuver to naming the disease with DLCO.
Related Specialties
Pulmonary function testing connects directly to these areas.