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BMJ Open Respir Res. 2018 Mar 25;5(1):e000264. doi: 10.1136/bmjresp-2017-000264. eCollection 2018.

Effect of idiopathic thoracic scoliosis on the tracheobronchial tree.

Author information

1
School of Engineering, University of Edinburgh, Edinburgh, UK.
2
Scottish National Spine Deformity Service, Royal Hospital for Sick Children, Edinburgh, UK.

Abstract

Introduction:

High prevalence of obstructive lung disease has been reported in patients undergoing surgical correction of thoracic scoliosis. Airway narrowing due to spine morphology is analysed as a contributing factor.

Methods:

Preoperative surgical planning CTs of 34 patients with right-sided thoracic scoliosis (age: 17.6±9.0) were retrospectively analysed and compared with 15 non-scoliotic controls (age: 16.3±5.1). Three-dimensional models of spine and airway lumen were reconstructed. Based on thoracic sagittal profile, patients were divided into hypokyphosis (HypoS: <10°), normal kyphosis (NormS: ≥10° and <40°) and hyperkyphosis (HyperS: ≥40°) groups. Lumen area of bronchi, bifurcation angles and minimum spine-airway distance were measured. Pulmonary function tests were correlated to scoliosis, kyphosis and lumen area.

Results:

Loss of kyphosis led to proximity between bronchus intermedius (BI) and spine. HypoS (NormS) had lumen area reductions in the right main bronchus of 29% (19%), BI of 45% (23%), right middle lobar bronchus of 46% (32%) and right lower lobe bronchus (RLL7) of 66% (37%), respectively (P<0.05). The lower right superior segmental bronchus was reduced across all scoliotic groups (P<0.05). Airways were displaced caudal by 0.65±0.45 vertebra in patients with scoliosis. Loss of kyphosis correlated negatively with forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC), FVC/(FVC predicted) and FEV1/(FEV1 predicted) (P<0.01). Lumen area of trachea, right upper lobar bronchus, BI and RLL7 correlated negatively with FEV1/FVC. BI and RLL7 narrowing were strong predictors of FVC and FEV1 loss (P<0.001).

Conclusions:

Right-sided main stem airways are narrowed in HypoS and NormS. Loss of kyphosis leads to narrowing of BI and its trifurcation. FEV1/FVC correlated negatively with airway narrowing, implying an obstructive element to lung function impairment in patients with scoliosis and hypokyphosis.

KEYWORDS:

lung physiology; paediatric lung disaese; paediatric physician; thoracic surgery

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