Pulmonary function and flow-volume loop patterns in patients with tracheobronchomalacia.

Area of Science:

• Respiratory Medicine
• Pulmonary Diagnostics

Background:

• Tracheobronchomalacia (TBM) is a condition affecting the airways.
• Limited data exists on pulmonary function test (PFT) and flow-volume loop patterns in TBM.
• Previous studies suggested four main flow-volume loop morphologies in TBM.

Purpose of the Study:

• To describe common PFT and flow-volume loop patterns in a large cohort of patients with symptomatic moderate to severe TBM.
• To evaluate the utility of PFTs and flow-volume loops in diagnosing clinically important TBM.

Main Methods:

• Retrospective analysis of prospectively collected data from 90 patients with TBM symptoms.
• Evaluation of PFT results and flow-volume loops from January 2002 to December 2008.
• Categorization of ventilatory defects and flow-volume loop morphologies.

Main Results:

• 44.4% of subjects had obstructive ventilatory defects, 17.8% restrictive, and 16.7% mixed.
• Among subjects with available flow-volume loops, low maximum forced expiratory flow was most common (81.6%).
• A significant proportion of patients (21.1% by PFTs, 17.1% by flow-volume loops) had normal or non-distinctive results.

Conclusions:

• PFTs and flow-volume loops can be normal in a substantial number of patients with moderate to severe TBM.
• These tests alone should not be the sole basis for determining the presence or clinical importance of TBM.
• Further diagnostic approaches may be necessary for TBM evaluation.