INTRODUCTION
Congenital lung malformations (CLM) are rare and a heterogeneus group of disorders including abnormal and dysfunctional pulmonary parenchyma and airways. Congenital lung malformations are a large spectrum of disorders such as congenital pulmonary airway malformation (CPAM), congenital lobar emphysema (CLE), bronchogenic cyst (BC), bronchopulmonary sequestration (BPS)1. Surgical resection is the definitive treatment for these lesions with a controversy of elective surgery or conservative treatment in the management of asymptomatic patients and standard surgical treatment method is lobectomy2-4. After resection of abnormal congenital lesion, lung volume and function may be expected to improve.
Small peripheral airways are defined as conducting airways and gas exchange bronchioli and alveolar ducts with luminal diameter less than 2 mm. Despite representing large amount of total lung volume, peripheral airways contribute little to overall airway resistance. Therefore peripheral airways can not be evaluated by spirometry which assesses large airways’ flow and resistance5. Changes and impairment in peripheral small airway structure with pathological processes, affects the distribution of ventilation among different parallel lung units and cause ventilation inhomogeneity6,7.
Lung Clearance Index (LCI) is a lung function test derived from multiple breath washout technique. It is defined as dividing cumulative expired volume calculated by assessment of the number of respiratory turnovers required to clear saturated inert gas from the lungs, into functional residual capacity. It exhibits ventilation distribution and reflects peripheral airway status7. As LCI is feasible for young children measurements are performed during tidal breathing without require forced expiratory maneuvers8-10.
In early stages of chronic progressive lung diseases without increased general airway resistance, LCI may be much more specific than spirometry to demonstrate periferic airway involvement7,8.
Data on long-term lung function in children with postoperative CLMs is rare and in the published articles spirometry is the most preferred method11-13. Although surgical resection of the affected part may facilitate the compensatory growth of the remaining lung, it may cause inhomogeneity of ventilation distribution. Depending on this fact, LCI may be more appropriate to evaluate peripherical airway function.
The primary objective of this study is to evaluate the long term lung function of patients who had lobectomy for CLM. As a secondary objective, diagnostic accuracy of LCI and spirometry was compared in patients and healthy controls.