Pneumopericardium is rare - defined as a collection of air or gas in the pericardial space.
The amount of air required to produce haemodynamic changes depends on the volume and rate of introduction:
- haemodynamic changes may occur with as little as 60 ml of air if it is introduced rapidly
- up to 500 ml may accumulate into the pericardium without marked effect if introduced slowly into the pericardial space (1)
Aetiology can be divided into three broad categories.
- most common cause is trauma:
- blunt or penetrating chest injury and barotrauma are included in this category:
- barotrauma is usually secondary to positive pressure ventilation (both invasive and noninvasive)
- most commonly occurring in neonatal practice
- however cases associated with severe asthma, prolonged labour and cocaine inhalation may occur
- second category - fistulation between pericardium and a hollow or air-containing structure e.g. pleural space, pulmonary substance, bronchial tree, gastrointestinal tract
- examples include
- staphylococcal lung abscess rupture
- erosion into the pericardium as a result of a bronchial carcinoma
- gastropericardial fistula complicating peptic ulcer disease
- third category - much less common is secondary to gas production de novo by microorganisms invading the pericardial sac e.g. Clostridium perfringens and Klebsiella
Two distinctive clinical signs associated with pneumopericardium.
- splashing ‘mill wheel’ murmur - this was described in the first description of this condition by Bricketeau in 1844. The case was in fact one of pyopneumopericardium. The 'mill wheel' murmur described was a result of the combination of fluid and gas in the pericardial space
- presence of shifting tympany - revealed when the precordium is percussed in the recumbent and upright positions
Investigations in pneumopericardium include:
- ECG - may reveal signs of pericarditis; at the point of tamponade then bradycardia is said to be common
- CXR - may allow differentiation between pneumopericardium and pneumomediastinum
- may show ‘transverse band of air’ sign - represents air within the transverse sinus of the pericardium.
- 'transverse band of air' sign is not present in pure pneumomediastinum or medial pneumothorax
- CT scan - demonstrates pericardial air; also may provide diagnostic clues to the aetiology of the pneumopericardium
- barium contrast swallow - may demonstrate an oesophagopericardial fistula
- negative result cannot completely exclude this diagnosis
- echocardiography - may reveal pathognomonic spontaneous contrast within the pericardial space; also may show features of cardiac tamponade if present
Management:
Seek expert advice.
- in the absence of tension then, in general, treatment is aimed at the specific cause
- if signs of tamponade develop then
- urgent pericardiocentesis is required
- a pericardial catheter should be left in place in order to prevent the development of further tension
Prognosis:
- pneumopericardium - one review revealed a 57% all-cause mortality
- pyopneumopericardium - has an even higher associated mortality rate
Reference:
- Stacey S et al. A case of spontaneous tension pneumopericardium. Br J Cardiol 2004;11:32-14.