Comparison of pre and postoperative structural features following lung volume reduction surgery

Purpose: To determine the relationship between radiographically determined thoracic structure, movement, and clinical outcome. Methods: We reviewed the clinical records and pre and postoperative inspiratory and expiratory chest radiographs in 100 sequential patients. Lung height and width at multiple levels, diaphragm length, excursion of the chest wall and diaphragm, diaphragm radius of curvature, and zone of apposition were compared with clinical measures before and 6 months after surgery. Results: Complete records were available in 82 patients. Following surgery, there were decreases in the diameter of the thorax, lung height, and radius of diaphragm curvature and increases in chest wall and diaphragm excursion. Diaphragm zone of apposition increased 7mm. Patients with a larger post-operative increase in diaphragm excursion had greater clinical improvement in FEV₁ (r=.47, p=.01) and exercise tolerance (r=.40, p=.03). Chest Size Pre (cm) Post (cm) Change Lung height 28.3±2.1 25.4±2.8 2.9(10%)* Max AP diameter 23.1±2.3 22.2±1.8 0.9(4%) Max transverse 30.2±3.0 29.7±2.9 0.5(2%)* Diaphragm Radius insp. 20.9±0.9 19.0±0.8 1.9(10%) Radius expir. 15.6±0.5 14.3±0.5 1.3(8%) Length insp. 17.7±2.1 17.0±2.1 0.7(4%) Length expir. 17.9±2.1 17.2±2.1 0.7(4%) Excursion Diaphragm** 1.7±1.1 2.5±1.5 0.8(47%) AP chest 1.0±0.6 1.1±0.9 0.1(10%) Transverse 1.3±0.7 1.5±0.8 0.2(15%) *p<.001, paired t-test **Normal is >3.0cm. Conclusions: Reduced thoracic distention and increased excursion following surgery, particularly changes in the diaphragm, support the hypothesis of improved respiratory movements as a contributing factor to the clinical improvement seen following surgery. Clinical Implications: These findings suggest that the degree of distention and impairment in respiratory movements might be an important consideration in the patient selection process.