pneumomediastinum & Pneumopericardium

35-year-old alcoholic man came to ER with Chest pain & dyspnea..

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

Stacey S et al. A case of spontaneous tension pneumopericardium. Br J Cardiol 2004;11:32-14.