SESSION TITLE: Pulmonary Function Testing
SESSION TYPE: Slide Presentations
PRESENTED ON: Sunday, March 23, 2014 at 04:15 PM - 05:15 PM
PURPOSE: In typical restriction, there is a proportionate reduction in the TLC and in the FVC (TLC %pred-FVC %pred < 5%). In some patients there is a disproportionate reduction in the FVC as compared to the TLC (TLC %pred-FVC %pred ≥5%) along with an increase in the residual volume. We call this pattern ‘complex restriction’ (CR). This study aims to better understand the clinical and pulmonary function profile of patients with CR as compared to typical restriction.
METHODS: From Nov 2009-June 2013, we identified 4532 patients with restriction (TLC < LLN) of whom 2021 patients were classified as CR. Of these, we identified a subgroup of 46 patients who were significantly restricted (TLC %pred-FVC %pred > 25% and RV > ULN) and compared them to 50 patients with simple restriction (TLC %pred-FVC %pred < 5%).
RESULTS: Patients with complex restriction (CR) (n=46) were more likely to be diagnosed with neuromuscular weakness (p=0.0003), diaphragmatic dysfunction (p=0.02) or COPD (p = 0.02) and were less likely to be diagnosed with an interstitial lung disease (p < 0.0001). Chest x-rays in CR patients were more likely to show pleural thickening (p= 0.01) and less likely to show lung fibrosis (p=0.005). Similarly, on Chest CT scans, patients with CR were more likely to show atelectasis (p= 0.001) and less likely to have findings of interstitial lung disease (p= 0.004).
CONCLUSIONS: Complex restriction is a distinct pattern that can be easily identified in patients with restriction. It is characterized by elevated residual volumes and an FVC that is disproportionately reduced as compared to the TLC. Patients with CR are more likely to be diagnosed with neuromuscular weakness, COPD, chest wall deformity or atelectasis whereas interstitial lung disease and lung fibrosis are less frequently seen in this group of patients.
CLINICAL IMPLICATIONS: Recognition of this pattern will allow clinicians to appropriately diagnose and manage their patients with restrictive lung disorders.
DISCLOSURE: The following authors have nothing to disclose: Brittany Dykstra, Vivek Iyer, Kenneth Parker, Robert Hyatt, Paul Scanlon
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