PEDIATRIC
SURGEON'S
WORKSHOP
Diagnostic Pneumomediastinum By W. A. Cumming and J. S. Simpson
A
3-yr-old girl had a chest roentgenogram performed because of a respiratory tract infection. It showed an apparent anterior mediastinal mass extending to the left, above and anterior to the heart (Fig. 1). The differential diagnosis included congenital heart disease, thymic t u m o r or cyst, and a large left lobe of normal thymus gland. Heart disease was ruled out clinically but fluoroscopy and conventional tomography failed to rule out a tumor or cyst (Fig. 2). PROCEDURE
Using mild sedation and local anesthesia, a diagnostic pneumomediastinum was performed. An 18-gauge disposable needle, bent into a semicircle, was guided over the suprasternal notch with its tip down against the posterior aspect o f the manubrium (Fig. 2A). Fifty cubic centimeters of nitrous oxide was injected under fluoroscopic control. Once this gas was seen in the anterior mediastinum, a further injection of 100 cc of oxygen was made. It was immediately apparent at fluoroscopy that the apparent mass was a large normal left lobe of thymus gland. This was confirmed by t o m o g r a p h y (Fig. 2B). Recently, we have used a Teflon intravenous catheter with a removable steel
Fig. 1. (A) Anteroposterior roentgenogram of the chest showing the full context density in the region of the left upper cardiac border, as indicated by the arrow. (B) Tomogram not helping in the definition of a separate anterior mediastinal mass.
From the Hospital for Sick Children, Toronto, Ontario, Canada. Address for reprint requests: James S. Simpson, M.D., 170 St. George St., Suite 421, Toronto, Ontario, M5R 2M8, Canada. 9 1975 by Grune & Stratlon, Inc. Journal of Pediatric Surgery, Vol. 10, No. 6 (December), 1975
971
972
A
PEDIATRIC SURGEON'S WORKSHOP
i[
Fig. 2. (A) Graph demonstrating technique of anterior mediastinal oxygen injection to produce a pneumomediastinum. (B) Tomogram following the introduction of a pneumomediastinum showing quite clearly the typically shaped left lobe of the thymic gland~
needle. This was bent by hand into a semicircle and, when the tip was behind the manubrium, the needle was removed, leaving the plastic catheter in position. Because children may become restless, the catheter seems less likely to damage any structures in the area. DISCUSSION
Diagnostic pneumomediastinography is not a new procedure. It was described by Condorelli in 1936 and there are many reports of its use since then. Indications for the procedure have included investigation of bronchogenic carcinoma, lymphoma, parathyroid adenoma, and myasthenia gravis. Suggested routs of injection include suprasternal, xiphisternal, transternal, paravertebral, paratracheal, transtracheal, and presacral. Gases used have included air, carbon dioxide, nitrous oxide, and oxygen. We believe that the suprasternal injection of nitrous oxide and oxygen is a safe and easy method of identifying the thymus gland in children with suspected anteromediastinal masses. There are no reported complications due to this technique. REFERENCES 1. Hare WSC, Mackay IR: Radiological assessment of thymic size in myasthenia gravis and systemic lupus erythematosus. Lancet 1: 746-748, 1963 2. Hughes DL, Hanafee W, O'Loughlin BJ:
Diagnostic pneumomediastinum. 78:12-18, 1962
Radiology
3. Simecek C: Diagnostic pneumomediastinography. Dis Chest 53:24-29, 1968
SURGEON'S
WORKSHOP
Diagnostic Pneumomediastinum By W. A. Cumming and J. S. Simpson
A
3-yr-old girl had a chest roentgenogram performed because of a respiratory tract infection. It showed an apparent anterior mediastinal mass extending to the left, above and anterior to the heart (Fig. 1). The differential diagnosis included congenital heart disease, thymic t u m o r or cyst, and a large left lobe of normal thymus gland. Heart disease was ruled out clinically but fluoroscopy and conventional tomography failed to rule out a tumor or cyst (Fig. 2). PROCEDURE
Using mild sedation and local anesthesia, a diagnostic pneumomediastinum was performed. An 18-gauge disposable needle, bent into a semicircle, was guided over the suprasternal notch with its tip down against the posterior aspect o f the manubrium (Fig. 2A). Fifty cubic centimeters of nitrous oxide was injected under fluoroscopic control. Once this gas was seen in the anterior mediastinum, a further injection of 100 cc of oxygen was made. It was immediately apparent at fluoroscopy that the apparent mass was a large normal left lobe of thymus gland. This was confirmed by t o m o g r a p h y (Fig. 2B). Recently, we have used a Teflon intravenous catheter with a removable steel
Fig. 1. (A) Anteroposterior roentgenogram of the chest showing the full context density in the region of the left upper cardiac border, as indicated by the arrow. (B) Tomogram not helping in the definition of a separate anterior mediastinal mass.
From the Hospital for Sick Children, Toronto, Ontario, Canada. Address for reprint requests: James S. Simpson, M.D., 170 St. George St., Suite 421, Toronto, Ontario, M5R 2M8, Canada. 9 1975 by Grune & Stratlon, Inc. Journal of Pediatric Surgery, Vol. 10, No. 6 (December), 1975
971
972
A
PEDIATRIC SURGEON'S WORKSHOP
i[
Fig. 2. (A) Graph demonstrating technique of anterior mediastinal oxygen injection to produce a pneumomediastinum. (B) Tomogram following the introduction of a pneumomediastinum showing quite clearly the typically shaped left lobe of the thymic gland~
needle. This was bent by hand into a semicircle and, when the tip was behind the manubrium, the needle was removed, leaving the plastic catheter in position. Because children may become restless, the catheter seems less likely to damage any structures in the area. DISCUSSION
Diagnostic pneumomediastinography is not a new procedure. It was described by Condorelli in 1936 and there are many reports of its use since then. Indications for the procedure have included investigation of bronchogenic carcinoma, lymphoma, parathyroid adenoma, and myasthenia gravis. Suggested routs of injection include suprasternal, xiphisternal, transternal, paravertebral, paratracheal, transtracheal, and presacral. Gases used have included air, carbon dioxide, nitrous oxide, and oxygen. We believe that the suprasternal injection of nitrous oxide and oxygen is a safe and easy method of identifying the thymus gland in children with suspected anteromediastinal masses. There are no reported complications due to this technique. REFERENCES 1. Hare WSC, Mackay IR: Radiological assessment of thymic size in myasthenia gravis and systemic lupus erythematosus. Lancet 1: 746-748, 1963 2. Hughes DL, Hanafee W, O'Loughlin BJ:
Diagnostic pneumomediastinum. 78:12-18, 1962
Radiology
3. Simecek C: Diagnostic pneumomediastinography. Dis Chest 53:24-29, 1968
