Few small studies have reported the characteristics of PFTs in patients with tracheobronchomalacia (TBM). Four main expiratory flow volume loop (FVL) patterns have been associated with TBM: low peak flow, biphasic expiratory curve, flow oscillation and notching. However, these patterns have been neither sensitive nor specific to TBM. Our objective is to describe common pulmonary function test (PFT) and FVL patterns among the largest series of patients to date undergoing evaluation for moderate to severe TBM.
A descriptive study based on review of PFTs and FVLs of 90 consecutive patients evaluated for moderate to severe TBM.
The median age of patients in this sample was 65 years (31–95 years), 40 (44%) patients were men, 44 (48.9%) met GOLD criteria for COPD, and 21 (23%) had been diagnosed with asthma. Of 90 PFTs, 40 (44.4%) had obstruction, 16 (17.8%) had definite or highly likely restriction, 15 (16.7%) had a mixed defect, and 19 (21.1%) were within normal limits. FVLs were available on 76 patients. Among 76 patients with FVL, the most frequent finding was low FEFmax 62 (81.6%), followed by biphasic morphology 16 (21.1%), notched expiratory loop 7 (9.2%) and expiratory oscillations 2 (2.6%).The balance of patients 13 (17.1%) had no distinctive FVL characteristics. Biphasic morphology was most common among patients with COPD.
Irrespective of a clinical diagnosis of COPD or asthma, the most common pattern seen in the flow volume loops of patients with TBM was low FEFmax.
The FVL and PFTs in patients with TBM are frequently abnormal; however, their usefulness for the diagnosis of TBM is likely limited. In our clinical database, TBM is very commonly seen among patients who also meet clinical and laboratory criteria for COPD.
Andres Sosa, No Financial Disclosure Information; No Product/Research Disclosure Information