Body plethysmography cannot diagnose COPD on its own; it serves as a critical component of a broader diagnostic pathway. Clinicians use it alongside spirometry and DLCO tests to confirm air trapping or hyperinflation. According to the 2024 GOLD report, a post-bronchodilator FEV1/FVC ratio of less than 0.70 is the primary requirement for a COPD diagnosis. We use plethysmography to determine the specific severity and phenotype of the condition once it’s identified.