The Many Faces of Pneumomediastinum: An Observational Study

Abstract

BACKGROUNDPneumomediastinum is an uncommon condition which is defined by the presence of air in the mediastinum. It may result from a number of causes, but at times the underlying aetiology remains obscure. The present study aims to review the clinical and imaging features in patients who presented with pneumomediastinum alone or in association with other findings in order to establish the aetiological diagnosis. We report here, a series of cases with pneumomediastinum of various unusual aetiologies and also the clinical profile, predisposing factors and outcome of these patients along with the associated complications. METHODSWe retrospectively reviewed the records of all patients who presented to the respiratory unit of our hospital with the diagnosis of pneumomediastinum over a period of 2 years from 2013-2015. The cases of pneumomediastinum resulting from trauma and iatrogenic causes were excluded from the study. RESULTSA total of six patients (4 males and 2 females) with pneumomediastinum were identified during the study period after applying the exclusion criteria. The most common presenting symptom in these cases was shortness of breath followed by dry cough, chest pain and fever. Subcutaneous emphysema and Hamman sign was identified in one patient each. Of the six cases, preexisting lung disease was identified in 3 patients and these included connective tissue disease related interstitial lung disease in two cases and combined pulmonary fibrosis and emphysema in one case. In the remaining three cases, the causes of pneumomediastinum were Pneumocystis carinii pneumonia (PCP) in HIV positive patient, pulmonary tuberculosis in another and spontaneous oesophageal perforation in the third. Coexisting pneumothorax was present in 3 out of 6 cases. The mean duration of hospital stay in these six patients was 8 days. No recurrence of pneumomediastinum was seen in any of the six patients during six months of followup. CONCLUSIONSPneumomediastinum is a condition with diverse aetiologies. It is important to identify the underlying cause of pneumomediastinum in order to manage these patients. Spontaneous pneumomediastinum needs to be differentiated from secondary pneumomediastinum as the latter is a more morbid condition and has to be managed promptly in order to avoid unfavourable outcome.

Pneumomediastinum- Cause and Consequence

“…It is a relatively uncommon condition however the actual prevalence could be higher than that reported in literature due to underdiagnosis. 4 Pneumomediastinum can be produced in general by three different mechanisms (1) gas forming organisms present in an infection of the mediastinum or adjacent areas (2) rupture of mucosal or cutaneous barriers as occurring in oesophageal or tracheobronchial perforation (3) The Macklin effect based on the inter alveolar and lung interstitial pressure gradient. Increased intrathoracic pressure leads to dissection of air along the bronchovascular sheath into the mediastinum causing pneumomediastinum and into the subcutaneous tissue causing subcutaneous emphysema.…”