FIGURE 5. Restrictive spirometry pattern, the FVC and FEV1 are <LLN but the FEV1/FVC is >LLN. The flow–volume loop is narrow indicating low volumes. FVC, forced vital capacity; FEV1, forced expiratory volume in the first second; FEV3, forced expiratory volume in the third second; M, median; LLN, lower limit of normal.
