Surgical Correction of Severe Scoliosis Leads to Changes in Central Airway Resistance Evaluated with CT-Based 3D Reconstruction and Impulse Oscillometry

BACKGROUND: Previous studies have not compared airway resistance and morphological parameters before and after the treatment of severe scoliosis. In the present study, 3-dimensional (3D) computed tomographic (CT) reconstruction and impulse oscillometry (IOS) were used to evaluate the changes in airway dilation and airway resistance caused by posterior spinal fusion for the treatment of severe kyphoscoliosis. METHODS: Thirty-four patients with severe scoliosis (Cobb angle, >100°) underwent posterior spinal fusion. Preoperative and postoperative evaluations included CT scans, radiographic assessment, and IOS. Changes in bronchial dilation were evaluated with use of 3D CT reconstruction, and changes in airway resistance were evaluated with use of IOS. Differences were assessed with use of 2-tailed paired Student t tests, and correlations were evaluated with use of the Spearman rank test. RESULTS: Nearly all spinal radiographic measurements improved after posterior spinal fusion. The mean Cobb angle was 133.21° ± 22.15° preoperatively and 50.92° ± 13.37° postoperatively (p < 0.001). The mean thoracic kyphosis angle was 121.42° ± 32.42° preoperatively and 50.67° ± 5.21° postoperatively (p < 0.001). The IOS measurements improved, with the reactance at 20 Hz (R20) decreasing from 0.4029 ± 0.0747 to 0.3100 ± 0.0837 kPa/(L/s) (p = 0.0004). Following posterior spinal fusion, the trachea, left main bronchus, and right main bronchus expanded. Moreover, the diameter and lumen area of the trachea were moderately correlated with R20 (r = -0.5071, p = 0.0114; r = -0.5537, p = 0.0050) and the diameter and lumen area of the right main bronchus were correlated with R20 (r = -0.5583, p = 0.0056; r = -0.6389, p = 0.0008). R20 and the lumen area of the trachea were correlated with the thoracic kyphosis angle (r = 0.6394, p = 0.0004; r = -0.6160, p = 0.0023). CONCLUSIONS: Posterior spinal fusion can safely and effectively improve the curve and relieve airway obstruction in patients with severe scoliosis. Impulse oscillometry analysis suggested that R20 substantially increased after posterior spinal fusion, primarily because of altered central airway enlargement as measured with CT reconstruction. LEVEL OF EVIDENCE: Therapeutic Level IV . See Instructions for Authors for a complete description of levels of evidence.