Background

Pneumopericardium is the presence of air within the pericardial space. The most common etiologies include iatrogenic factors, positive pressure mechanical ventilation, and less commonly pericardial infections with gas producing organisms [1]. It is a rare complication in cases with bacterial necrotizing pneumonia and proven to be lethal, further leading to cardiac tamponade and hemodynamic instability [2]. The overall mortality of pneumopericardium has been estimated as 57% [3].

Case presentation

A 21-year-old male, known case of T-cell ALL status post-chemotherapy, presented with relapse of ALL. His presenting complaints were breathlessness, fever, burning micturition, and he was further evaluated for febrile neutropenia. Laboratory workup showed pancytopenia with a total leukocyte count (TLC) of 300. The patient was transferred to intensive care on day 8 of his admission in view of severe breathlessness. HRCT chest on day 11 of admission showed evidence of multifocal consolidations in bilateral lung parenchyma, predominantly involving the lower lobes (Fig. 1). The bronchoalveolar lavage came out to be acinetobacter positive. HRCT chest on day 17 of admission showed interval appearance of cavitatory changes, suggestive of necrotizing pneumonia (Fig. 2). The patient developed acute respiratory distress syndrome (ARDS) and deteriorated further. The patient was intubated and kept on positive pressure ventilation. On day 23 of admission, chest X-ray showed evidence of pneumopericardium (Fig. 3). Pericardiocentesis was performed. Air leak from the pericardial catheter was synchronous with mechanical ventilation, which strongly suggested a pericardial communication with the airway. Follow-up HRCT chest was done to look for the underlying etiology, which showed interval increase in cavitatory consolidations and interval appearance of moderate to significant pneumopericardium. A subsegmental area of air space consolidation was seen encasing the medial segmental bronchus of the right middle lobe with eccentric cavitation, showing trans-pericardial contiguity with resultant broncho-pericardial fistula. Significant compression over cardiac chambers, predominantly on right atrium and right ventricle was also seen. The pericardial drain was seen in situ in posterior pericardial cavity, as well as bilateral pleural effusions (Fig. 4). The patient unfortunately succumbed to cardiopulmonary arrest the very next day, despite aggressive management.

Fig. 1
figure 1

High-resolution computed tomography chest (lung window) on day 11 of admission shows multiple patchy to confluent areas of air space opacifications in bilateral lung parenchyma

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Fig. 2
figure 2

High-resolution computed tomography chest (lung window) on day 17 of admission redemonstrates areas of air space opacifications with interval appearance of internal areas of breakdown

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Fig. 3
figure 3

X-ray chest (Antero-posterior view) on day 23 of admission shows areas of inhomogeneous opacities in central as well as peripheral locations in bilateral lung fields. The heart is seen outlined by air, consistent with significant pneumopericardium with mass effect on the underlying heart

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Fig. 4
figure 4

Non-contrast computed tomography Chest on day 24 of admission shows subsegmental area of consolidation encasing medial segmental bronchus of the right middle lobe, with eccentric cavitation showing transpericardial contiguity. Significant pneumopericardium with cardiac air tamponade is also noted. Note is made of bilateral pleural effusions. Pericardial catheter is seen lying in posterior pericardial cavity (blue arrow). Note the presence of broncho-pericardial fistula (white arrow)

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Discussion

Pneumopericardium should always raise a suspicion for broncho-pericardial fistula, tracheo-pericardial or gastro-pericardial fistula. The causative factors include blunt trauma, penetration trauma, carcinoma, or iatrogenic [4]. Other less common causes are bacterial necrotizing pneumonia, HIV, hepatitis, and invasive pulmonary aspergillosis. In this case, due to the immunocompromised status of the patient, he developed necrotizing pneumonia. Acinetobacter baumannii is a rare cause of necrotizing pneumonia which is highly virulent and shows antimicrobial resistance compared with other organisms [5]. Complications of necrotizing pneumonia include parapneumonic effusions, pleural empyema, and bronchopleural fistula. In our case, the patient developed the rare complication of secondary broncho-pericardial fistula formation from cavitatory changes alongside the pericardium and resultant tension pneumopericardium. Mass effect on the heart was seen, causing impairment of right ventricular filling, resulting in pericardial tamponade with increase and equalization of intracardiac pressures, pulsus paradoxus, arterial hypotension, and resultant cardiogenic shock [6]. Pneumopericardium often does not require any specific treatment. However, in view of tension pneumopericardium, traditional therapy such as tube decompression was employed in our case.

Conclusions

Our case illustrates broncho-pericardial fistula as a rare complication of necrotizing pneumonia and the utility of multimodality imaging for the diagnosis of bronchopericardial fistula and tension pneumopericardium.