quent descending necrotizing mediastinitis, have recently been reviewed in a study of31 patients. The cause is usually an anaerobic or polymicrobial infection involving the posterior mediastinum, resulting in anterior displacement of the trachea. Despite aggressive management, including tracheostomy to deal with upper airway obstruction, cervical and mediastinal drainage, the introduction of antibiotics and the use of computed tomographic (Clj scans, the diagnosis is often delayed and mortality remains at 40 percent. • Bronchogenic cysts can involve the mediastinum and may often be asymptomatic. Respiratory distress is most unusual. Roentgenographic features reveal a smooth, round, homogeneous, noncalcified mass, most often in the subcarinal location, but it can extend to involve the posterior, middle, or superior mediastinum. Esophageal displacement to the left is commonly observed. 3 In a pediatric series, only 15 percent presented with a cervical mass and 10 percent presented with respiratory distress. Fever and recurrent pneumonia are the most frequently observed symptoms. Mediastinal extension was found in 20 percent. The cr scans were the most helpful diagnostic procedure in two thirds of the patients. The lesions are radiopaque with smooth margins that may often compress bronchi and produce respiratory distress. There was no report of upper airway obstruction in this series. • Our patient had features of both a fixed and variable intrathoracic upper airway obstruction on his flow volume loop. His flows plateaued on both inspiration and expiration, with more plateauing on the expiratory loop (Fig 1). The FEF50/FIF50 ratio was extremely low (FIF50=0.97, FEF50=2.00, ratio=0.48), indicating a variable intrathoracic component and easily differentiated from chronic obstructive pulmonary disease (COPD) by the shape of the curve. These findings were confinned on bronchoscopic examination. First described by Miller and Hyatt,• the flow volume loop has proved to be fairly sensitive and specific in diagnosing the three major types of upper airway obstruction. Scarred strictures from previous intubation, as well as large goiters, most commonly produced circumpharyngeal fixed orifices that do not respond to transmural forces regardless oflocation. This results in the typical trapezoidal shape of the flow volume loop. The FEF50/FIF50 usually remains close to 1 in these situations. Tumors of the trachea are the most frequent reasons for variable intrathoracic obstruction, with rarer causes being chondromalacia, relapsing polychondritis, and tracheobronchomegaly. The FEF50/FIF50 is usually far less than 1 in these patients. Benign unilateral vocal cord paralyses accounts for the majority of patients with variable extrathoracic obstruction. In these patients, the FEF50/FIF50 ratio is far greater than 1.8 •7 Bronchogenic cysts that migrate to the posterior mediastinum may impinge on the soft membranous, posterior tracheal wall, resulting in severe narrowing of the intrathoracic trachea, which can be life-threatening. Its early recognition, with prompt institution of therapy, can be lifesaving.

2 Estrera AS, Landay MJ, Grisham JM, Sinn DP, Platt MR. Descending necrotizing mediastinitis. Surg Gnyecol Obstet 1983; 157:545-52 3 Rogers LF, Osmer JC. Bronchogenic cyst. AJR 1964; 91:273-83 4 Ramenofsky ML, Leape GG, McCauley RGK. J Pediatr Surg 1979; 14:219-24 5 Miller D, Hyatt R. Obstructing lesions of larynx and trachea: clinical and physiologic characteristics. Mayo Clin Proc 1969; 44:145-60 6 Miller D, Hyatt R. Evaluation of obstructing lesions of the trachea and larynx by flow-volume loops. ARRD 1973; 108:475-81 7 Kryger M, Bode F, Antic R, Anthonisen N. Diagnosis of obstruction of the upper and central airways. Am J Med 1976; 61:85-93

Thoracoscopic Nd:YAG Laser Resection of a Solitary Pulmonary Nodule* Robert D. Dowling, M.D.; Rodney J Landreneau, M.D., F.C.C.P.; Michael E. Wachs, M.D.; and ftter F. Ferson, M.D.

Advances in endoscopic surgical techniques and laser technology have expanded the role of thoracoscopy. We report a thoracoscopic resection of a benign pulmonary lesion. A 44-year-old man underwent a successful Nd:YAG laser-assisted thoracoscopic resection of a peripheral lung hamartoma. The patient's postoperative course was uncomplicated. Thoracotomy with its attendant morbidity was avoided. Continued success with thoracoscopic resection will have a significant impact on the management of select patients with peripheral, solitary pulmonary nodules. (Cheat 1992; 102:1903-05)

T

he efficacy of Nd:YAG laser in performing open pulmonary resections 1•2 coupled with recent advances in endoscopic surgical techniques led us to explore the possibility of laser-assisted thoracoscopic pulmonary resection. This report describes the successful thoracoscopic resection of a benign pulmonary nodule. CASE REPORT

REFERENCES

A 44-year-old healthy white man wa~ admitted to Presbyterian University Hospital, Pittsburgh, Pa, for operative management of a herniated lumbar vertebral disc. A routine preoperative chest roentgenogram revealed a 1.5-cm nodule adjacent to the right heart border. Computerized tomography of the chest and upper abdomen revealed a 1.5-cm, noncalcilled solitary pulmonary nodule adjacent to the right atrium (Fig 1). There was no mediastinal or hilar adenopathy. The patient reported cigar smoking on rare occasions but denied cigarette smoking. There was no history of recent travel or exposure to pulmonary toxins. The patient underwent pulmonary function studies which were normal. Three years prior to admission, the patient was evaluated for a chronic nonproductive cough. Bronchoscopy and chest roentgenograms at that time were normal as was computerized tomography of the chest and upper abdomen. We believed the lesion was not amenable to percutaneous biopsy due to its location adjacent to the heart (Fig 1). After an uneventful recovery from the lumbar disc surgery, the patient was admitted for bronchoscopy and pulmonary resection. The bronchoscopic assessment was entirely normal without endobronchial lesions. The patient was intubated with a double lumen

1 Forrest Jv. Shackelford CD, Bramson RF, Anderson LS. Acute mediastinal widening. Radiology 1973; 117:881-85

*From the Section of Thoracic Surgery, University of Pittsburgh, Pittsburgh. CHEST I 102 I 6 I DECEMBER, 1992

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FJgrt•t• Hopkins tt•lt·s~'lpt•, No. 26040A. Karl Ston Endost"pic Amt•rica lne, Culver City, Cal) was intnxlueed through an ll-mm diameter troear (Autosuture Surgiport Troears, United States Surgical Corp. Norwalk, Conn) placed in the sixth intert"stal spaet> 2 em mt>dial to the antt•rior axillary line. Two 7-mm diameter troears wt•re then placed in the fifth and seventh interStal spaces at the mid-axillary line under direet thora