European Journal of Radiology, 15 (1992) 0
1992 Elsevier
EURRAD
Science Publishers
7-10
B.V. All rights reserved.
0720-048X/92/$05.00
00274
Tension mediastinal emphysema: emergency percutaneous drainage with CT guidance R.F. Dondelinger a, M. Coulona, J.C. Kurdziel” and M. Hemmerb “Department of Diagnostic and Interventional Radiology and bDepartment of Surgical Intensive Care, Centre Hospitalier, Luxembourg, Luxembourg
(Received
10 October
Key words: Thorax, emphysema;
1991; accepted
Computed
21 December
tomography,
1991)
thorax; Radiology, interventional
Abstract
Four patients aged 8 to 54 years, clinical symptoms of compromised with a diameter varying from F12 aspiration. Emergency treatment
under mechanical ventilation, presented with sudden tension mediastinal emphysema and exhibited typical venous return. Diagnosis of tension mediastinal emphysema was confirmed by CT. A percutaneous catheter to F20 was inserted in the anterior mediastinal compartment with CT control and connected to a waterseal was effkient in all patients. Percutaneous aspiration was continued for 3 to 20 days.
Introduction Mediastinal emphysema or pneumomediastinum was described in detail by Laennec [ 11. Dyspnea and precordial chest pain are the most common clinical symptoms. Physical examination may reveal a thoracic or cervical subcutaneous emphysema and occasionally a crunch can be heard over the mediastinal area. Radiographic confirmation is required for a definite diagnosis. The most severe clinical presentation is tension mediastinal emphysema, which was reported in single patients [ 2-61 or in limited series [ 7,8], mainly children and newborn. Tension within a large air collection confined to the mediastinum is responsible for compromised venous return, which may evolve into a life threatening condition, if refractory to medical management. Successful treatment of tension mediastinal emphysema dates back to 1884 [9] ; several incisions were made with a knife at the sites where thoracic subcutaneous emphysema was prominent. Needle aspiration of subcutaneous air was advocated [ lo] until decomAddress for reprints: Prof. R.F. Dondelinger, Department of Diagnostic and Interventional Radiology, Centre Hospitalier, 4 Rue Barb16 - L-1210 Luxembourg.
pression incision or mediastinotomy became standard emergency therapy [2,11,12]. We report four patients with tension pneumomediastinum, efftciently treated with continuous aspiration through a percutaneous catheter, placed in the mediastinal emphysema with CT guidance. Case reports Case 1 A 22 year-old male was admitted following a motor vehicle accident. The patient was in deep coma, had a right hemiplegia and severe respiratory distress, necessitating tracheal intubation. CT of the brain revealed contusion of both frontal lobes and diffuse cerebral oedema. Radiological evaluation disclosed a fracture of the posterior arch of the sixth cervical vertebra, multiple left rib fractures and other minor peripheral bone fractures. Chest radiography and thoracic CT evidenced contusion of the lower lobe of both lungs and a minimal left pneumothorax. Two days following admission, chest radiography showed a major left pneumothorax and subcutaneous emphysema. Peak airway pressure (PAP) was 45 cm H,O and positive end expiratory pressure (PEEP) at 6 cm H,O. Fraction of inspired oxygen (Fi 0,) was increased at 70%, Central venous
8
pressure (CVP) was 13 mm Hg. The pneumothorax was treated with a chest tube, but the patient did not improve. Chest radiography and thoracic CT confirmed mediastinal emphysema, pushing the heart posteriorly and limiting expansion of both lungs (Fig. la). The pneumomediastinum extended into the posterior and superior mediastinal compartment and pneumoretroperitoneum was present. An F16 chest tube was placed percutaneously with CT control in the anterior and superior mediastinum by a left anterolateral approach and was connected to a waterseal aspiration with a negative pressure of 10 cm H,O (Fig. lb). CVP was 12 mm Hg and Fi 0, was decreased at 40%. The mediastinal catheter was removed in error three days later. On the following days, subsequent bilateral tension pneumothoraces occurred and were drained. Mediastinal emphysema persisted without recurrence of tension (Fig. lc). The patient left the intensive care unit 28 days after admission. Case 2 A 41 year-old alcoholic female was admitted for “etat de mal”. Previous history included bilateral pneumonia, complicated by a right pleural empyema. Insertion of two thoracostomy tubes in another hospital was inefficient. The patient was intubated for adult respiratory distress syndrom (ARDS) secondary to septicemia. CVP was + 5 mm Hg. The patient was ventilated with PAP at 46 cm H,O, PEEP at 8 cm H,O and Fi 0, of 50%. The general condition of the patient deteriorated rapidly. On the fourth day, she exhibited subcutaneous emphysema, with CVP of 20-30 cm H,O. Diuresis was 20 ml/hour. She was ventilated with Fi 0, of 80-loo”/,, PAP of 49 cm H,O and PEEP of 8 cm H,O. Thoracic CT demonstrated a left loculated pneumothorax with mild tension and subcutaneous emphysema. The pneumothorax was drained with a chest tube. On the next day, the patient was hypoxic
again. Mechanical ventilation with PAP of 50 cm H,O and Fi 0, of 100% was continued. CVP persisted at 25 mm Hg and diuresis was nearly non-existent (< 10 ml/hour). Thoracic CT evidenced tension mediastinal emphysema with compression of the heart and of large mediastinal veins. An F14 catheter with multiple sideholes was placed percutaneously in the anterior and superior mediastinum by a left parasternal approach and connected to a waterseal aspiration with a negative pressure of 15 cm H,O. Following drainage of tension mediastinal emphysema, the patient improved dramatically: CVP decreased at 5-10 mm Hg, diuresis returned and hypoxemia vanished. Thoracic CT performed two days later confirmed persistent mediastinal emphysema without tension. The patient improved continuously and the mediastinal catheter was removed 20 days after insertion. A final thoracic CT confirmed resolution of mediastinal air. Case 3 An eight year-old boy who had been on haemodialysis for one year for juvenile nephronophtisis was admitted to receive a kidney transplant. In the operating theater, after injection of human antilymphocytic immunoglobulin (Pressimmun), he went into anaphylactic shock. The patient was intubated and ventilated with 100% oxygen and a PEEP of 12 cm H,O. Chest radiography on the next day showed ARDS. Four days after starting mechanical ventilation, subcutaneous emphysema extended from neck to scrotum. Arterial pressure was 120/50 mm Hg, pulse rate 140 c/min, CVP 17 mm Hg.. The patient was ventilated with Fi 0, of 100x, PAP of 30 cm H,O and PEEP of 12 cm H,O. Diuresis was 8 ml/hour. Tension mediastinal emphysema was clinically evident and confirmed by thoracic CT. The air collection dissected the anterior mediastinum along its entire length and pushed the heart posteriorly (Fig. 2a). Percutaneous drainage was performed with an F7
Fig. 1. (a) Extensive mediastinal tension emphysema compressing the mediastinal vessels and both lungs, the trachea is pushed posteriorly. (b) Percutaneous CT guided insertion of an F16 chest tube (-+) in the anterior mediastinal air collection. (c) Persistent mediastinal emphysema without tension following percutaneous decompression.
Fig. 2. (a) Massive mediastinal tension emphysema with severe compression of the mediastinal vessels and flattening of the main bronchi. Extensive pulmonary ARDS and right lateral subcutaneous emphysema. (b) The heart is pushed posteriorly by the mediastinal tension emphysema. Percutaneous left lateral retrosternal puncture of the mediastinal air collection (-) and insertion of an F7 pigtail catheter with multiple sideholes. (c) Return of the heart to normal position after decompression of mediastinal tension emphysema. The F7 pigtail catheter is located in the collapsed anterior mediastinal compartment (+).
angiographic pig-tail catheter by a left parasternal approach with CT control and connected to a waterseal aspiration at a negative pressure of 15-30 cm H,O (Fig. 2b). CVP decreased at 8 mm Hg and hypoxia improved: Fi 0, was decreased at 60% on the 7th day. Thoracic CT performed two days later showed persistent mediastinal emphysema without tension (Fig. 2~). Cardiac and respiratory decompensation recurred two days later with arterial pressure of 180/120 mm Hg, tachycardia at 140 c/min. Subcutaneous emphysema increased again. Thoracic CT demonstrated tension mediastinal emphysema and a left pneumothorax, responsible for massive pulmonary compression. The mediastinal F7 pigtail catheter was exchanged for an F 14 abscess drainage catheter and the pneumothorax was drained with an F 12 chest tube. The patient showed an immediate positive clinical response. The mediastinal catheter was removed after 12 days. The patient recovered fully and left the intensive care unit 19 days after admission. Renal transplantation was carried out nine months later.
mechanical ventilation. During this time period, multiple bilateral pneumothoraces occurred without pneumomediastinum. Two days after tracheal extubation, the pleural drains being clamped, the patient had acute superior vena caval obstruction syndrome. Subcutaneous emphysema was present, arterial pressure was 170 mm Hg and pulse rate 140 c/min. The patient was intubated again with Fi 0, at 7036, PEEP at 20 cm H,O, and PAP was at 30 cm H,O Thoracic CT confirmed tension mediastinal emphysema with compression of both lungs and the heart. The tension mediastinal emphysema was drained with CT control; an F20 chest tube was introduced percutaneously into the anterior mediastinum with CT control by a left parasternal approach. The heart was decompressed and both lungs re-expanded immediately. Pulse rate decreased to 100 c/min and arterial pressure to 130/80 mm Hg. The patient was extubated three days later and the mediastinal drain was removed 10 days after insertion. She left the intensive care unit 20 days after tension mediastinal emphysema had appeared.
Case 4 A 54 year-old female was admitted for abdominal pain and fever. She had undergone cholecystectomy and hepatico-jejunostomy four years before and had experienced several episodes of cholangitis. Abdominal CT demonstrated two liver abscesses and dilated bile ducts in the lateral segment of the left lobe, which was atrophic. Massive ARDS developed secondary to sepsis. Percutaneous hepatic abscess drainage was successful and followed by left lateral hepatectomy. Mechanical ventilation was continued for ARDS during the post-operative period with a PEEP of 20 cm H,O. The patient was extubated after 3 months of
Discussion Mediastinal emphysema or pneumomediastinum is generated by distinct pathophysiological mechanisms: disruption of air-containing structures, gas producing infection and so-called spontaneous mediastinal emphysema, which occurs in patients with or without any clinical abnormality and is caused by a large variety of conditions. In hospital patients, the main cause of mediastinal emphysema is mechanical ventilation with high PAP and PEEP. The basic condition for mediastinal emphysema is interstitial pulmonary emphysema, due
10
to alveolar rupture caused by increased alveolar pressure. Penetration of air in the mediastinum occurs along the interstitial tissue contained in the bronchovascular sheaths. When mediastinal pressure rises abruptly, the mediastinal pleura may rupture, resulting in pneumothorax. Bilateral or left sided pneumothorax was present in our four patients during their hospital stay. Radiological recognition of pneumomediastinum can be problematic on chest radiographs when mediastinal air volume is limited. The mediastinal air collection is best recognized with CT, particularly when extensive subcutaneous emphysema overlies endothoracic structures on bedside chest radiographs. Identification of the source of mediastinal air is crucial for management. In most cases, mediastinal emphysema is well tolerated. Conservative management is sufficient and spontaneous regression is the rule [6]. Tension mediastinal emphysema may develop in ventilated patients if cervical or subphrenic escape routes for mediastinal air were obliterated by previous surgery or scars. Clinical symptoms include dyspnea, cyanosis, hypotension, oligoanuria, and cardiovascular collapse mimicking acute cardiac tamponade. Association with tension pneumothorax worsens the clinical symptoms. In our four patients, tension mediastinal emphysema alone was responsible for the impaired cardiovascular status. Prompt therapy must be established before clinical evidence of cardiac tamponade or increase of intracranial pressure. Limited mediastinostomy is usually performed by an incision above or below the sternum, below the clavicle or lateral to the sternum, followed by blunt dissection to open the retrosternal space or by insertion of a chest tube in the mediastinum under direct vision. These manceuvres proved generally to be efficient, without serious complications [2,3,5-81. A suprasternal incision may occasionally fail and need full sternotomy [ 41. Percutaneous CT guided insertion of a mediastinal drainage catheter is a useful therapeutic adjunct following confirmation of tension mediastinal emphysema and avoids the hazards of blind catheter insertion or limited mediastinostomy. Usual percutaneous drainage catheters or chest tubes with variable diameters are used. Catheters with multiple sideholes are necessary to avoid obstruction of the sideholes by the connective mediastinal tissue. The best percutaneous approach is anterolateral, the extremity of the catheter being placed behind the sternum in the superior or inferior mediastinal compartment when large mediastinal vessels or the heart are pushed posteriorly by the pneumomediastinum. The internal mammary vessels and large mediastinal vessels are avoided by the course of the catheter. When a
pneumothorax is present, insertion of the mediastinal catheter is facilitated before the pneumothorax is treated. The trocard technique is usually adequate for catheter insertion in the mediastinum. A continuous waterseal aspiration with slight negative pressure is maintained during 1 to 3 weeks until signs of tension have vanished without recurrence. Mediastinal emphysema without symptoms of tension may persist in patients undergoing mechanical ventilation following percutaneous decompression. In three of the four patients reported, clinical response was dramatic following mediastinal drainage. Conclusion In intubated and ventilated patients with limited pultension mediastinal monary function, symptomatic emphysema should not be left untreated. Percutaneous catheter insertion in the mediastinum is optimally achieved with CT guidance during a diagnostic CT examination and was proven efficient as an emergency decompression. References
4
5
6
I
8
9
10
11 12
Laennec RTH. Traite de 1’Auscultation Mediate. Paris: Asselin et Cie, 1879. Van Stiegman G, Brantigan CO, Hopeman AR. Tension mediastinum. Arch Surg 1977; 112: 1212-1215. Tyler DC, Redding G, Hall D, Lynn A. Increased intracranial pressure: an indication to decompress a tension pneumomediastinum. Crit Care Med 1984; 12: 467-468. Shennib HF, Barkun AN, Matouk E, Blundell PE. Surgical decompression of a tension pneumomediastinum. Chest 1988; 93: 1301-1302. Beg MH, Reyazuddin Ansari MM. Traumatic tension pneumomediastinum mimicking cardiac tamponade. Thorax 1988; 43: 576-577. Rosenfeld DL, Cordell CE, Jadeja N. Retrocardiac pneumomediastinum: radiographic finding and clinical implications. Pediatrics 1990; 85: 92-97. Pfenninger J, Bossi E, Biesold J, Blumberg A. Treatment of pneumothorax, pneumopericardium and pneumomediastinum. Helv Paediatr Acta 1982; 37: 353-360. Moore JT, Wayne EH, Hanson J. Malignant pneumomediastinum: successful tube mediastinostomy in the neonate. Am J Surg 1987; 154: 688-691. Bishopp. Rapid and extensive emphysema with severe collapse from passage of cart wheel over the thorax treated at one with marked relief with multiple punctures of the skin: rapid convalescence. Br Med J 1884; 1: 163-164. Jewet TC Jr, Adler RH, Taheri SA. Tension pneumomediastinum in the newborn. J Thorac Cardiovasc Surg 1960; 43: 540-547. Tiegel M. Ein einfaches Verfahren zur Beklmpfung des mediastinalen Emphysema. Zentralbl Chir 1911; 38: 420-423. Rydell JR. Emergency cervical mediastinostomy for massive mediastinal emphysema. Arch Surg 1955; 70: 647-653.
1992 Elsevier
EURRAD
Science Publishers
7-10
B.V. All rights reserved.
0720-048X/92/$05.00
00274
Tension mediastinal emphysema: emergency percutaneous drainage with CT guidance R.F. Dondelinger a, M. Coulona, J.C. Kurdziel” and M. Hemmerb “Department of Diagnostic and Interventional Radiology and bDepartment of Surgical Intensive Care, Centre Hospitalier, Luxembourg, Luxembourg
(Received
10 October
Key words: Thorax, emphysema;
1991; accepted
Computed
21 December
tomography,
1991)
thorax; Radiology, interventional
Abstract
Four patients aged 8 to 54 years, clinical symptoms of compromised with a diameter varying from F12 aspiration. Emergency treatment
under mechanical ventilation, presented with sudden tension mediastinal emphysema and exhibited typical venous return. Diagnosis of tension mediastinal emphysema was confirmed by CT. A percutaneous catheter to F20 was inserted in the anterior mediastinal compartment with CT control and connected to a waterseal was effkient in all patients. Percutaneous aspiration was continued for 3 to 20 days.
Introduction Mediastinal emphysema or pneumomediastinum was described in detail by Laennec [ 11. Dyspnea and precordial chest pain are the most common clinical symptoms. Physical examination may reveal a thoracic or cervical subcutaneous emphysema and occasionally a crunch can be heard over the mediastinal area. Radiographic confirmation is required for a definite diagnosis. The most severe clinical presentation is tension mediastinal emphysema, which was reported in single patients [ 2-61 or in limited series [ 7,8], mainly children and newborn. Tension within a large air collection confined to the mediastinum is responsible for compromised venous return, which may evolve into a life threatening condition, if refractory to medical management. Successful treatment of tension mediastinal emphysema dates back to 1884 [9] ; several incisions were made with a knife at the sites where thoracic subcutaneous emphysema was prominent. Needle aspiration of subcutaneous air was advocated [ lo] until decomAddress for reprints: Prof. R.F. Dondelinger, Department of Diagnostic and Interventional Radiology, Centre Hospitalier, 4 Rue Barb16 - L-1210 Luxembourg.
pression incision or mediastinotomy became standard emergency therapy [2,11,12]. We report four patients with tension pneumomediastinum, efftciently treated with continuous aspiration through a percutaneous catheter, placed in the mediastinal emphysema with CT guidance. Case reports Case 1 A 22 year-old male was admitted following a motor vehicle accident. The patient was in deep coma, had a right hemiplegia and severe respiratory distress, necessitating tracheal intubation. CT of the brain revealed contusion of both frontal lobes and diffuse cerebral oedema. Radiological evaluation disclosed a fracture of the posterior arch of the sixth cervical vertebra, multiple left rib fractures and other minor peripheral bone fractures. Chest radiography and thoracic CT evidenced contusion of the lower lobe of both lungs and a minimal left pneumothorax. Two days following admission, chest radiography showed a major left pneumothorax and subcutaneous emphysema. Peak airway pressure (PAP) was 45 cm H,O and positive end expiratory pressure (PEEP) at 6 cm H,O. Fraction of inspired oxygen (Fi 0,) was increased at 70%, Central venous
8
pressure (CVP) was 13 mm Hg. The pneumothorax was treated with a chest tube, but the patient did not improve. Chest radiography and thoracic CT confirmed mediastinal emphysema, pushing the heart posteriorly and limiting expansion of both lungs (Fig. la). The pneumomediastinum extended into the posterior and superior mediastinal compartment and pneumoretroperitoneum was present. An F16 chest tube was placed percutaneously with CT control in the anterior and superior mediastinum by a left anterolateral approach and was connected to a waterseal aspiration with a negative pressure of 10 cm H,O (Fig. lb). CVP was 12 mm Hg and Fi 0, was decreased at 40%. The mediastinal catheter was removed in error three days later. On the following days, subsequent bilateral tension pneumothoraces occurred and were drained. Mediastinal emphysema persisted without recurrence of tension (Fig. lc). The patient left the intensive care unit 28 days after admission. Case 2 A 41 year-old alcoholic female was admitted for “etat de mal”. Previous history included bilateral pneumonia, complicated by a right pleural empyema. Insertion of two thoracostomy tubes in another hospital was inefficient. The patient was intubated for adult respiratory distress syndrom (ARDS) secondary to septicemia. CVP was + 5 mm Hg. The patient was ventilated with PAP at 46 cm H,O, PEEP at 8 cm H,O and Fi 0, of 50%. The general condition of the patient deteriorated rapidly. On the fourth day, she exhibited subcutaneous emphysema, with CVP of 20-30 cm H,O. Diuresis was 20 ml/hour. She was ventilated with Fi 0, of 80-loo”/,, PAP of 49 cm H,O and PEEP of 8 cm H,O. Thoracic CT demonstrated a left loculated pneumothorax with mild tension and subcutaneous emphysema. The pneumothorax was drained with a chest tube. On the next day, the patient was hypoxic
again. Mechanical ventilation with PAP of 50 cm H,O and Fi 0, of 100% was continued. CVP persisted at 25 mm Hg and diuresis was nearly non-existent (< 10 ml/hour). Thoracic CT evidenced tension mediastinal emphysema with compression of the heart and of large mediastinal veins. An F14 catheter with multiple sideholes was placed percutaneously in the anterior and superior mediastinum by a left parasternal approach and connected to a waterseal aspiration with a negative pressure of 15 cm H,O. Following drainage of tension mediastinal emphysema, the patient improved dramatically: CVP decreased at 5-10 mm Hg, diuresis returned and hypoxemia vanished. Thoracic CT performed two days later confirmed persistent mediastinal emphysema without tension. The patient improved continuously and the mediastinal catheter was removed 20 days after insertion. A final thoracic CT confirmed resolution of mediastinal air. Case 3 An eight year-old boy who had been on haemodialysis for one year for juvenile nephronophtisis was admitted to receive a kidney transplant. In the operating theater, after injection of human antilymphocytic immunoglobulin (Pressimmun), he went into anaphylactic shock. The patient was intubated and ventilated with 100% oxygen and a PEEP of 12 cm H,O. Chest radiography on the next day showed ARDS. Four days after starting mechanical ventilation, subcutaneous emphysema extended from neck to scrotum. Arterial pressure was 120/50 mm Hg, pulse rate 140 c/min, CVP 17 mm Hg.. The patient was ventilated with Fi 0, of 100x, PAP of 30 cm H,O and PEEP of 12 cm H,O. Diuresis was 8 ml/hour. Tension mediastinal emphysema was clinically evident and confirmed by thoracic CT. The air collection dissected the anterior mediastinum along its entire length and pushed the heart posteriorly (Fig. 2a). Percutaneous drainage was performed with an F7
Fig. 1. (a) Extensive mediastinal tension emphysema compressing the mediastinal vessels and both lungs, the trachea is pushed posteriorly. (b) Percutaneous CT guided insertion of an F16 chest tube (-+) in the anterior mediastinal air collection. (c) Persistent mediastinal emphysema without tension following percutaneous decompression.
Fig. 2. (a) Massive mediastinal tension emphysema with severe compression of the mediastinal vessels and flattening of the main bronchi. Extensive pulmonary ARDS and right lateral subcutaneous emphysema. (b) The heart is pushed posteriorly by the mediastinal tension emphysema. Percutaneous left lateral retrosternal puncture of the mediastinal air collection (-) and insertion of an F7 pigtail catheter with multiple sideholes. (c) Return of the heart to normal position after decompression of mediastinal tension emphysema. The F7 pigtail catheter is located in the collapsed anterior mediastinal compartment (+).
angiographic pig-tail catheter by a left parasternal approach with CT control and connected to a waterseal aspiration at a negative pressure of 15-30 cm H,O (Fig. 2b). CVP decreased at 8 mm Hg and hypoxia improved: Fi 0, was decreased at 60% on the 7th day. Thoracic CT performed two days later showed persistent mediastinal emphysema without tension (Fig. 2~). Cardiac and respiratory decompensation recurred two days later with arterial pressure of 180/120 mm Hg, tachycardia at 140 c/min. Subcutaneous emphysema increased again. Thoracic CT demonstrated tension mediastinal emphysema and a left pneumothorax, responsible for massive pulmonary compression. The mediastinal F7 pigtail catheter was exchanged for an F 14 abscess drainage catheter and the pneumothorax was drained with an F 12 chest tube. The patient showed an immediate positive clinical response. The mediastinal catheter was removed after 12 days. The patient recovered fully and left the intensive care unit 19 days after admission. Renal transplantation was carried out nine months later.
mechanical ventilation. During this time period, multiple bilateral pneumothoraces occurred without pneumomediastinum. Two days after tracheal extubation, the pleural drains being clamped, the patient had acute superior vena caval obstruction syndrome. Subcutaneous emphysema was present, arterial pressure was 170 mm Hg and pulse rate 140 c/min. The patient was intubated again with Fi 0, at 7036, PEEP at 20 cm H,O, and PAP was at 30 cm H,O Thoracic CT confirmed tension mediastinal emphysema with compression of both lungs and the heart. The tension mediastinal emphysema was drained with CT control; an F20 chest tube was introduced percutaneously into the anterior mediastinum with CT control by a left parasternal approach. The heart was decompressed and both lungs re-expanded immediately. Pulse rate decreased to 100 c/min and arterial pressure to 130/80 mm Hg. The patient was extubated three days later and the mediastinal drain was removed 10 days after insertion. She left the intensive care unit 20 days after tension mediastinal emphysema had appeared.
Case 4 A 54 year-old female was admitted for abdominal pain and fever. She had undergone cholecystectomy and hepatico-jejunostomy four years before and had experienced several episodes of cholangitis. Abdominal CT demonstrated two liver abscesses and dilated bile ducts in the lateral segment of the left lobe, which was atrophic. Massive ARDS developed secondary to sepsis. Percutaneous hepatic abscess drainage was successful and followed by left lateral hepatectomy. Mechanical ventilation was continued for ARDS during the post-operative period with a PEEP of 20 cm H,O. The patient was extubated after 3 months of
Discussion Mediastinal emphysema or pneumomediastinum is generated by distinct pathophysiological mechanisms: disruption of air-containing structures, gas producing infection and so-called spontaneous mediastinal emphysema, which occurs in patients with or without any clinical abnormality and is caused by a large variety of conditions. In hospital patients, the main cause of mediastinal emphysema is mechanical ventilation with high PAP and PEEP. The basic condition for mediastinal emphysema is interstitial pulmonary emphysema, due
10
to alveolar rupture caused by increased alveolar pressure. Penetration of air in the mediastinum occurs along the interstitial tissue contained in the bronchovascular sheaths. When mediastinal pressure rises abruptly, the mediastinal pleura may rupture, resulting in pneumothorax. Bilateral or left sided pneumothorax was present in our four patients during their hospital stay. Radiological recognition of pneumomediastinum can be problematic on chest radiographs when mediastinal air volume is limited. The mediastinal air collection is best recognized with CT, particularly when extensive subcutaneous emphysema overlies endothoracic structures on bedside chest radiographs. Identification of the source of mediastinal air is crucial for management. In most cases, mediastinal emphysema is well tolerated. Conservative management is sufficient and spontaneous regression is the rule [6]. Tension mediastinal emphysema may develop in ventilated patients if cervical or subphrenic escape routes for mediastinal air were obliterated by previous surgery or scars. Clinical symptoms include dyspnea, cyanosis, hypotension, oligoanuria, and cardiovascular collapse mimicking acute cardiac tamponade. Association with tension pneumothorax worsens the clinical symptoms. In our four patients, tension mediastinal emphysema alone was responsible for the impaired cardiovascular status. Prompt therapy must be established before clinical evidence of cardiac tamponade or increase of intracranial pressure. Limited mediastinostomy is usually performed by an incision above or below the sternum, below the clavicle or lateral to the sternum, followed by blunt dissection to open the retrosternal space or by insertion of a chest tube in the mediastinum under direct vision. These manceuvres proved generally to be efficient, without serious complications [2,3,5-81. A suprasternal incision may occasionally fail and need full sternotomy [ 41. Percutaneous CT guided insertion of a mediastinal drainage catheter is a useful therapeutic adjunct following confirmation of tension mediastinal emphysema and avoids the hazards of blind catheter insertion or limited mediastinostomy. Usual percutaneous drainage catheters or chest tubes with variable diameters are used. Catheters with multiple sideholes are necessary to avoid obstruction of the sideholes by the connective mediastinal tissue. The best percutaneous approach is anterolateral, the extremity of the catheter being placed behind the sternum in the superior or inferior mediastinal compartment when large mediastinal vessels or the heart are pushed posteriorly by the pneumomediastinum. The internal mammary vessels and large mediastinal vessels are avoided by the course of the catheter. When a
pneumothorax is present, insertion of the mediastinal catheter is facilitated before the pneumothorax is treated. The trocard technique is usually adequate for catheter insertion in the mediastinum. A continuous waterseal aspiration with slight negative pressure is maintained during 1 to 3 weeks until signs of tension have vanished without recurrence. Mediastinal emphysema without symptoms of tension may persist in patients undergoing mechanical ventilation following percutaneous decompression. In three of the four patients reported, clinical response was dramatic following mediastinal drainage. Conclusion In intubated and ventilated patients with limited pultension mediastinal monary function, symptomatic emphysema should not be left untreated. Percutaneous catheter insertion in the mediastinum is optimally achieved with CT guidance during a diagnostic CT examination and was proven efficient as an emergency decompression. References
4
5
6
I
8
9
10
11 12
Laennec RTH. Traite de 1’Auscultation Mediate. Paris: Asselin et Cie, 1879. Van Stiegman G, Brantigan CO, Hopeman AR. Tension mediastinum. Arch Surg 1977; 112: 1212-1215. Tyler DC, Redding G, Hall D, Lynn A. Increased intracranial pressure: an indication to decompress a tension pneumomediastinum. Crit Care Med 1984; 12: 467-468. Shennib HF, Barkun AN, Matouk E, Blundell PE. Surgical decompression of a tension pneumomediastinum. Chest 1988; 93: 1301-1302. Beg MH, Reyazuddin Ansari MM. Traumatic tension pneumomediastinum mimicking cardiac tamponade. Thorax 1988; 43: 576-577. Rosenfeld DL, Cordell CE, Jadeja N. Retrocardiac pneumomediastinum: radiographic finding and clinical implications. Pediatrics 1990; 85: 92-97. Pfenninger J, Bossi E, Biesold J, Blumberg A. Treatment of pneumothorax, pneumopericardium and pneumomediastinum. Helv Paediatr Acta 1982; 37: 353-360. Moore JT, Wayne EH, Hanson J. Malignant pneumomediastinum: successful tube mediastinostomy in the neonate. Am J Surg 1987; 154: 688-691. Bishopp. Rapid and extensive emphysema with severe collapse from passage of cart wheel over the thorax treated at one with marked relief with multiple punctures of the skin: rapid convalescence. Br Med J 1884; 1: 163-164. Jewet TC Jr, Adler RH, Taheri SA. Tension pneumomediastinum in the newborn. J Thorac Cardiovasc Surg 1960; 43: 540-547. Tiegel M. Ein einfaches Verfahren zur Beklmpfung des mediastinalen Emphysema. Zentralbl Chir 1911; 38: 420-423. Rydell JR. Emergency cervical mediastinostomy for massive mediastinal emphysema. Arch Surg 1955; 70: 647-653.
