PHYSIOLOGIC ASPECTS OF IDIOPATHIC UNILATERAL HYPERLUCENT LUNG, WITH A REVIEW OF THE LITERATURE

Surgically treated Swyer-James syndrome

Because patients with Swyer-James syndrome have almost always been treated conservatively, few reports exist of pathological findings of the lung in this syndrome. We report a case of this rare disease treated surgically and discuss pathological findings. A 36-year-old woman repeatedly contracted bronchitis and pneumothorax since adolescence, until April 26, 1997, when she reported chest pain and dyspnea. Chest X-ray on admission showed left pulmonary collapse with a slight deviation of the mediastinum toward the right. Chest computed tomography showed an apical bulla and emphysematous change in the left upper lobe. Pulmonary arteriography at age 17 showed hypoplasia of left pulmonary artery branches in the left upper lobe. Based on a diagnosis of Swyer-James syndrome, we conducted left upper lobectomy on May 2, 1997. Pathological examination of the resected left upper lobe showed marked emphysematous change, including an emphysematous bulla with destruction of alveolar structure and peribronchiolar fibrosis. No vascular abnormality was recognized in histology. Emphysematous change secondary to repeated bronchiolitis is believed to have led to her repeated pneumothorax.

Differential lung function in an infant with the Swyer-James syndrome

A previously healthy two year old boy had an adenoviral infection at the age of 13 months and developed hyperlucency of the left lung, chronic respiratory distress, and failure to thrive. Bronchodilators and steroid treatment had no effect. Radionuclide lung scans using an intravenous bolus of xenon-133 both before and after treatment showed substantially reduced function on the hyperlucent side and modestly reduced function on the other side. Fibreoptic bronchoscopy showed no structural abnormalities. Partial forced expiratory flow volume (PEFV) curves, generated from end inspiration by rapid compression of the chest wall with an inflatable jacket, were obtained from the total respiratory system and from each lung separately by inflating a Fogarty catheter in the contralateral mainstem bronchus. Expiratory flow rates and volumes during both tidal breathing and PEFV manoeuvres were considerably decreased in the hyperlucent lung. PEFV curves from the "healthy" right lung and from the total respiratory system were similar in shape and showed a moderately obstructive pattern. The right lung ventilated about four times as much as the left when measured by bronchospirometry and about three times as much when measured by the radionuclide technique. The lung scans appeared to reflect adequately the functional abnormality in this infant with the Swyer-James syndrome.

Cardiopulmonary performance at rest and during exercise in seven patients with increased transradiancy of one lung ("Macleod's syndrome")

A group of seven patients with increased transradiancy of one lung included four with chronic bronchitis. The function of the two lungs combined was assessed by measurement of the lung volumes, airway resistance, and carbon monoxide uptake at rest, and by measurement of pulmonary ventilation, gas exchange, blood gases, and cardiac output at rest and during steady state exercise. The contribution of the hypertransradiant lung to the overall functional abnormalities at rest was estimated using a radioactive gas technique.

All the patients had airway obstruction. Pulmonary gas exchange was only mildly affected at rest because of equal reduction of ventilation and perfusion in the abnormal lung, but during exercise ventilation-perfusion inequality increased in some of the patients. Cardiac output was low in five patients during exercise and in four there was excessive lactate production. The greatest physiological abnormalities were seen in two of the chronic bronchitics who had abnormalities of ventilation and perfusion in both lungs.

We suggest that a pulmonary vascular abnormality resulting in reduced cardiac output, as well as ventilatory impairment due to airway obstruction, may contribute to the limited exercise capacity of these patients.