|Year : 2006 | Volume
| Issue : 4 | Page : 154-157
Pneumomediastinum, simultaneous bilateral spontaneous pneumothorax and subcutaneous emphysema following burn
Ramakant Dixit1, Hetal Shah1, Kalpana Dixit2, NJ Shah1
1 Department of Chest Diseases & Tuberculosis, B.J. Medical College & Civil Hospital, Ahmedabad - 380016 Gujarat., India
2 Institute of Cardiology, B.J. Medical College & Civil Hospital, Ahmedabad - 380016 Gujarat., India
381/26, Ramganj, Ajmer - 305001 (Rajasthan).
Source of Support: None, Conflict of Interest: None
Clinical trial registration None
| Abstract|| |
Simultaneous bilateral spontaneous pneumothorax and pneumomediastinum with subcutaneous emphysema following burn is unreported in the literature. We describe such case in an 18-year-old male patient with possible mechanism of such presentation.
Keywords: Burn, Pneumomediastinum, Pneumothorax.
|How to cite this article:|
Dixit R, Shah H, Dixit K, Shah N J. Pneumomediastinum, simultaneous bilateral spontaneous pneumothorax and subcutaneous emphysema following burn. Lung India 2006;23:154-7
|How to cite this URL:|
Dixit R, Shah H, Dixit K, Shah N J. Pneumomediastinum, simultaneous bilateral spontaneous pneumothorax and subcutaneous emphysema following burn. Lung India [serial online] 2006 [cited 2020 Jan 27];23:154-7. Available from: http://www.lungindia.com/text.asp?2006/23/4/154/44390
| Introduction|| |
A more vigorous approach to antibiotic therapy and physiologic fluid replacement has resulted in reduced fatality from shock and sepsis, unmasking the high incidence & mortality of pulmonary complications among burn patients.  Approximately one-third of fire fatalities are due to smoke inhalation and/ or asphyxia, and the major morbidity in fire victims is related to pulmonary complications. 
The pulmonary complications in burn patients, specially following smoke inhalation may result primarily from direct chemical injury to the respiratory tract, or secondarily from circulatory, metabolic, or infectious complications of surface burn or from complications of therapeutic maneuvers such as oxygen therapy, tracheostomy, mechanical ventilation or aggressive fluid therapy.  Immediately recognizable pulmonary abnormalities are usually due to chemical pulmonary edema and inhalation pneumonitis. Complications manifested 2 to 5 days after injury include pulmonary microembolism, adult respiratory distress syndrome and atelectasis. Delayed complications are major pulmonary embolism, pneumonia, and adult respiratory distress syndrome. 
Pneumothorax and pneumomediastinum as a complication of burn is probably underreported in the literature. , The present report is first one on the occurrence of pneumomediastinum, simultaneous bilateral spontaneous pneumothorax and subcutaneous emphysema following burn.
| Case Report|| |
An 18-year-old male patient was admitted in burn unit of our hospital with thermal injury involving face & upper part of chest and shortness of breath. He had history of fall down over boiling milk followed by excessive shortness of breath within one hour of the incidence.
On physical examination he had sustained 30% second and third degree burns over face, neck and upper part of chest on left side. He was in respiratory distress with inspiratory stridor. The pulse was 110/min, blood pressure 100/70 mmHg, respiratory rate 40/min, temperature 98°F and SpO 2 84%. The patient was conscious, and had extensive surgical emphysema over the neck, chest and arms. Respiratory system examination revealed bilaterally reduced intensity of breath sounds, rhonchi & stridor. Throat examination revealed congestion and edema of epiglottis and vocal cords. The admitting chest X-ray revealed bilateral pneumothorax with extensive subcutaneous emphysema and linear hypertranslucent opacity along the cardiac margins suggestive of pneumomediastinum [Figure 1].
An urgent closed tube thoracostomy was performed on both sides with resultant decrease in respiratory distress and stridor. He was also given oxygen inhalation at high flow rates, intravenous dexamethasone, aminophylline, antibiotics (ceftazidime, cloxacillin and metronidazole), fluids and nebulised bronchodilators along with local care for surface burns. Since child was conscious with spontaneous breathing and improved with above mentioned therapy, endotracheal intubation or tracheostomy was deferred.
Laboratory studies revealed haemoglobin 11.2 gm%, total leucocyte count 5500/mm 3 , differential count - polymorphs 69%, lymphocytes 28%, eosinophils 2% and monocyte 1% with normal blood sugar, renal function tests, liver function tests & electrolytes etc. Swab culture from the burn wound revealed growth of Staphylococcus aureus, sensitive to the antibiotics, which were already given to the patient. A repeat chest-X-ray revealed expansion of lung on both sides with opacities in the upper lung fields suggestive of pneumonitis [Figure 2]. Bronchoscopic examination to assess the airway injury could not be done.
The child continued to improve with treatment and both chest tubes were removed after six days following normal chest X-ray [Figure 3]. Dexamethasone was gradually tapered & finally stopped after 15 days, however, antibiotics were continued for three weeks. The initial chest X-ray abnormalities were completely resolved on the 14th and 21st post-burn day.
Patient was discharged on hospital day 28, with topical therapy for surface burns. His pulmonary function tests were normal at the time of discharge.
| Discussion|| |
Pneumomediastinum or the mediastinal emphysema is not a common clinical condition, although it may occur in a wide variety of different disorders. The gas within the mediastinum can originate from five sites: the lung, the mediastinal airways, the oesophagus, the neck and the abdominal cavity.  Extension of gas from the air spaces of the pulmonary parenchyma into the interstitial tissues and thence into the mediastinum is the most common pathogenetic mechanism of pneumomediastinum. It is suspected by the presence of subcutaneous emphysema, mainly in the region of neck or may be diagnosed mainly by its characteristic radiological features. ,
Spontaneous pneumomediastinum is usually a benign and self limiting condition. However, some time danger arises if the mediastinal pressure rises abruptly or decompression does not occurs into the subcutaneous tissues. Potentially life threatening complications includes (i) Pneumothorax (ii) Tension pneumomediastinum leading to cardiac temponade effect (iii) Air block because of splinting action of the air within the connective tissue of lung further occluding the airways and lastly (iv) impedance of pulmonary vascular flow by air within the vascular sheaths. 
The medical literature gives extensive coverage to problems related to pneumomediastinum and unilateral spontaneous pneumothorax. However, little information is available on, occurrence of simultaneous bilateral spontaneous pneumothorax and pneumomediastinum following burn. In a review of 697 patients of burn cases having pulmonary complications, Pruitt et al  found only one case of spontaneous pneumothorax. He also found eight cases of pneumothorax as a complication of tracheostomy and one case secondary to rib fracture. In another study, Lee et al  studied plain chest radiographs of 45 patients from a major fire disaster to assess effect of smoke inhalation injury on lung. He found only one patient developed unilateral spontaneous pneumothorax and pneumomediastinum accompanied by surgical emphysema in the first 24 hours, and another patient a spontaneous pneumomediastinum only. Neither of these patients were being assisted by mechanical ventilation at that time. In the same series, one patient with pulmonary oedema developed bilateral pneumothoraces a week after admission, caused by insertion of a subclavian venous catheter on one side and by high positive pressure ventilation on the other. Bruce et al  studied incidence & course of pulmonary complications in 100 patients of their burn unit. They found clinically significant pulmonary complications in 22 patient and among them unilateral pneumothorax was seen in one patient only occurring 18 hours after admission. Putman & Coworkers  analysed chest radiographic findings in 21 patients with acute smoke inhalation and did not encountered pneumothorax or pneumomediastinum in their series. We could not find simultaneous occurrence of bilateral spontaneous pneumothorax & pneumomediastinum within 12 hours following burn in the available literature, as occurred in the present case.
We suggest that spontaneous pneumomediastinum in our case might have been caused by an air leak associated with a rise in intrathoracic pressure due to bouts of coughing. Moreover, the airway obstruction is a known complication of respiratory burn.  It may result from edema any where along the laryngotracheobronchial tree, from reflex bronchoconstriction or from peribronchial cuffs of edema which decrease the normal tethering action of the lung to hold the airways open. , With the history of frequent coughing coupled with clinical evidence of airflow obstruction in our case, we propose that these mechanisms caused sudden rise in the intrathoracic pressure, creating a pressure gradient between the distended alveoli & surrounding structures leading to rupture of the marginal alveoli at their bases. Since the mean pressure in the mediastinum is always lower than that in the peripheral lung parenchyma, air thus dissected proximally along the brochovascular sheath to the mediastinum & then decompressed into soft tissue components of the neck.
Pneumothorax following pneumomediastinum is uncommon but a known complication.  Once in the mediastinum, the extra alveolar air follows the path of least resistance and may rupture through the delicate mediastinal fascia & overlying pleura into the pleural space. Why this occurs in some individuals & not in others may be determined by local pleural scarring in some cases but is often not readily apparent.  Another mechanism for pneumothorax following alveolar rupture has been hypothesized,  in which air dissects towards the periphery of the lung rather than towards the mediastinum & ruptures via sub pleural blebs through the visceral surface of the lung. Any of the above two mechanism could be responsible for bilateral spontaneous pneumothorax in our case.
Management of pneumothorax in burn patient requires special attention. The presence of burn of the chest wall in association with pneumothorax greatly increases the possibility of intrapleural contamination occurring during therapy and greatly magnifies the likelihood of empyema with significant morbidity & even mortality in these patients. The placement of the thoracostomy tube may require compromise with the usual surgical dicta to avoid placement of the tube through the invariably infected, burned skin. Therefore, in burn patients, all possible attempts should be made to place chest tube through unburned skin & unburned skin should be removed as far as possible from the burn wound margin. 
In all burn patients, whenever there is severe dyspnoea, tachypnea, inspiratory retractions, diminished breath sounds and arterial blood gas evidence of alveolar hypoventilation (rising PaCO 2 ), mechanical assistance to respiration will be necessary. Since it may be difficult to decide whether the main obstruction is in the larynx or lower in the tracheobrochial tree, the upper airway should be assessed by direct or indirect laryngoscopy before swelling of head, neck or oropharynx and trismus complicate this examination.  In all such cases pneumothorax should be excluded by chest X-ray, which is more useful to diagnose bilateral pneumothorax, because clinical diagnosis may be difficult due to presence of similar findings on both the sides,  as occurred in our case.
Bilateral simultaneous pneumothorax is a grave emergency that may endanger the life of patient unless appropriate therapy is given immediately. Prompt recognition of condition may result in quicker diagnosis and decrease in morbidity & mortality.
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[Figure 1], [Figure 2], [Figure 3]