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Pulmonary function of children with tracheomalacia and associated clinical factors
Wicharn Boonjindasup1,2,3, Julie M Marchant3,4, Margaret S McElrea3,4
1Menzies School of Health Research, Child Health Division, NHMRC Centre for Research Excellence in Paediatric Bronchiectasis (AusBREATHE), Charles Darwin University, Casuarina, Northern Territory, Australia.
Insights
Spirometry in children with tracheomalacia shows a common "knee" pattern but lacks correlation with bronchoscopic findings. However, concurrent bronchomalacia significantly lowers airflow, indicating a more severe condition.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Diagnostic Imaging
Background:
- Tracheomalacia is a condition affecting children's airways, yet spirometry data is scarce.
- Understanding spirometry patterns can potentially inform clinical management of tracheomalacia.
- Flexible bronchoscopy is used to assess airway anatomy in tracheomalacia.
Purpose of the Study:
- To analyze spirometry indices, including the Empey index and flow-volume curve patterns, in children diagnosed with tracheomalacia.
- To investigate the association between spirometry findings and specific bronchoscopic features of tracheomalacia.
Main Methods:
- Retrospective review of flexible bronchoscopy and spirometry data from 53 children diagnosed with tracheomalacia between 2016 and 2019.
- Blinded evaluation of spirometry indices and tracheomalacia features (lumen reduction, malacic length, bronchomalacia).
- Multivariable regression analysis was employed to determine associations between spirometry and bronchoscopic findings.
Main Results:
- The mean peak expiratory flow (PEF) was below normal range, while other spirometry parameters (FEV1, FVC, FEF25-75%, FEV1/FVC) were within normal limits.
- The 'knee' pattern on the flow-volume curve was the most frequent pattern, observed in 73.6% of cases.
- Bronchomalacia was significantly associated with reduced FEV1, FEF25-75%, and PEF. Other features like lumen reduction and malacic length showed no significant association with spirometry indices.
Conclusions:
- The 'knee' pattern is prevalent in pediatric tracheomalacia, but the Empey index and other spirometry measures do not reliably characterize the condition.
- Spirometry indices did not correlate with specific bronchoscopic features of tracheomalacia.
- Children with concurrent tracheobronchomalacia exhibit significantly lower airflow compared to those with tracheomalacia alone.
Objectives:
Spirometry is easily accessible yet there is limited data in children with tracheomalacia. Availability of such data may inform clinical practice. We aimed to describe spirometry indices of children with tracheomalacia, including Empey index and flow-volume curve pattern, and determine whether these indices relate with bronchoscopic features.
Methods:
From the database of children with tracheomalacia diagnosed during 2016-2019, we reviewed their flexible bronchoscopy and spirometry data in a blinded manner. We specially evaluated several spirometry indices and tracheomalacia features (cross-sectional lumen reduction, malacic length, and presence of bronchomalacia) and determined their association using multivariable regression.
Results:
Of 53 children with tracheomalacia, the mean (SD) peak expiratory flow (PEF) was below the normal range [68.9 percent of predicted value (23.08)]. However, all other spirometry parameters were within normal range [Z-score forced expired volume in 1 s (FEV1 ) = -1.18 (1.39), forced vital capacity (FVC) = -0.61 (1.46), forced expiratory flow between 25% and 75% of vital capacity (FEF25%-75% ) = -1.43 (1.10), FEV1 /FVC = -1.04 (1.08)], Empey Index = 8.21 (1.59). The most common flow-volume curve pattern was the "knee" pattern (n = 39, 73.6%). Multivariable linear regression identified the presence of bronchomalacia was significantly associated with lower flows: FEV1 [coefficient (95% CI) -0.78 (-1.54, -0.02)], FEF25%-75% [-0.61 (-1.22, 0)], and PEF [-12.69 (-21.13, -4.25)], all p ≤ 0.05. Other bronchoscopic-defined tracheomalacia features examined (cross-sectional lumen reduction, malacic length) were not significantly associated with spirometry indices.
Conclusion:
The "knee" pattern in spirometry flow-volume curve is common in children with tracheomalacia but other indices, including Empey index, cannot be used to characterize tracheomalacia. Spirometry indices were not significantly associated with bronchoscopic tracheomalacia features but children with tracheobronchomalacia have significantly lower flow than those with tracheomalacia alone.
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