BackgroundThe severities of COPD (FEV1 % predicted) and airflow obstruction (FEV1/FVC) are considered to be due to both emphysema and small airways disease. To our knowledge, this has not been previously confirmed by combined measurements of emphysema and of small airway function. We hypothesized that small airways disease and emphysema extent contribute independently to the severity of both COPD and airflow obstruction.MethodsTwenty-six subjects with COPD underwent measurements with forced oscillation technique (FOT) at 6 Hz and single-breath nitrogen washout. Respiratory system resistance, respiratory system reactance (Xrs), and expiratory flow limitation (EFL) index (measured as mean inspiratory Xrs − expiratory Xrs) were derived from FOT. Closing volume/vital capacity (CV/VC) was derived from the washout. Emphysema extent was measured as low attenuation areas < −910 Hounsfield units, expressed as a percentage of CT scan lung volume from multislice CT scans taken at total lung capacity.ResultsSubjects were aged (mean ± SD) 69.6 ± 8.0 years. Postbronchodilator FEV1 was 64.8 ± 19.8% predicted, and diffusing capacity of lung for carbon monoxide was 50.7 ± 15.8% predicted. Emphysema extent was 22.6% ± 15.0% CT scan volume. CV/VC was 16.9% ± 7.9%; Xrs, −3.72 ± 3.03 cm H2O/L/s; and EFL index, 3.88 ± 3.93 cm H2O/L/s. In multiple regression analyses, FEV1/FVC was predicted by both emphysema and CV/VC (model r2 = 0.54, P < .0001) whereas FEV1 % predicted was predicted by emphysema and EFL index (model r2 = 0.38, P = .0014).ConclusionsThe severities of COPD and airflow obstruction are independently predicted by both small airways disease and emphysema extent.
Patient selection remains one of the most important aspects of successful surgery for bullous disease. Operation is indicated for patients who have incapacitating dyspnea with large bullae that fill more than 30% of the hemithorax and result in the compression of healthy adjacent lung tissue. Operation is also indicated for patients who have complications related to bullous disease such as infection or pneumothorax. Patients who have bullous disease in the presence of diffuse lung disease (emphysematous or nonemphysematous) should be evaluated on an individual basis and surgery should be performed on patients in whom even a small increase in pulmonary function might be of major benefit. Smoking cessation and outpatient pulmonary rehabilitation are required of all patients preoperatively. Patients should undergo PFTs including lung volumes by whole body plethysmography, spirometry, diffusion capacity, and arterial blood gas. CT remains the most important preoperative evaluation because it is useful assessing the extent of bullous disease and the quality of the surrounding lung tissue. The authors favor a minimally invasive technique through VATS whenever possible because it might allow for a quicker recovery and might be associated with less pain than is seen following thoracotomy. Modified Monaldi-type drainage procedures are also effective, especially in high-risk patients who cannot tolerate excisional procedures. Special care must be taken to avoid sacrifice of any potentially functional lung tissue. Lobectomies should be avoided whenever possible. The best results are seen in limited resections of large bullae that spare all surrounding functional pulmonary parenchyma. Postoperative complications are minimized through aggressive tracheobronchial toilet and vigorous chest physiotherapy. Adequate pain control in maintained throughout the postoperative period, initially by way of epidural infusion of morphine or fentanyl and later through oral opioids. Early ambulation and pulmonary rehabilitation also help minimize complications.
The initial imaging evaluation of a patient with a suspected tracheal abnormality is the chest radiograph, which is poor for detection of central airway lesions. Prior to the development of CT, planar tomography was performed to better evaluate the deep layers of the chest. Tomography is rarely performed today for chest imaging. There have been major advances in chest radiography techniques secondary to improvements in electronics and computer technology that might ultimately improve plain film assessment of the central airways.
The technical aspects of lung transplantation have been refined over the past two decades. Anomalous donor anatomy and suboptimal harvests do not preclude transplantation, but they must be appropriately dealt with to ensure good outcomes. New techniques have been developed to increase the donor pool. Techniques for recipient pneumonectomy and graft implantation have been optimized, and ways of dealing with difficult exposures and anatomic variants have been designed. Novel methods for prevention of ischemia-reperfusion injury have been developed based on experimental studies, but more complete clinical scrutiny is needed to determine their impact.
