Brief clinical and laboratory observation

The pericardial “window”: A rare etiologic factor in neonatal pneumopericardium

We present a case of tension pneumopericardium in a patient involved in a motor vehicle crash. This patient was treated initially with a percutaneously placed drain and then definitively by a video assisted thoracoscopic pericardial window.

Cardiac tamponade most commonly results from accumulation of blood or other fluids within the pericardial sac. However, there is a growing body of clinical evidence showing that pneumopericardium can lead to cardiac tamponade in a large number of patients. Including those in the present report, a total of 252 patients with pneumopericardium are available for review. Interestingly, cardiac tamponade developed in 94 patients, or 37% of this group, because of air within the pericardial space. Pneumopericardium resulting in tamponade most frequently occurs in trauma patients or in newborn infants requiring positive pressure ventilation. This syndrome can be recognized promptly because of its characteristic physical findings and radiographic features. Although air tamponade can be treated effectively by either needle aspiration or insertion of a pericardial tube, the development of a pneumopericardium is a bad prognostic sign. Out of the 221 patients reported in the literature whose outcome is known, 127 (57%) died. In the group with a tension pneumopericardium, the mortality was 56% (53 out of 94 patients). Even without the development of tension, however, pneumopericardium was associated with a 58% mortality (74 out of 127 patients) due to other underlying disease processes.

Thirteen premature infants receiving mechanical ventilation for respiratory distress syndrome developed pneumopericardium. All had high peak inflation pressures (mean, 42 mm Hg; range, 26 to 60 mm Hg), and all were on positive end-expiratory pressure (PEEP) ventilation (mean, 3.1 mm Hg; range, 2.1 to 5.7 mm Hg) at the time that pneumopericardium occurred. Arterial blood gases, indices of respiratory support, and hemodynamic data were reviewed before and after the onset of pneumopericardium in all patients. There was a statistically significant increase in peak inflation pressure (PIP) over the 16 hours prior to onset of pneumopericardium (p < 0.05). There was, however, no significant relationship between onset of pneumopericardium and other respiratory variables, including PEEP. In the majority of patients, pneumopericardium was associated with cardiac air tamponade. Various forms of treatment for pneumopericardium were attempted, including observation, needle aspiration, and insertion of pericardial tubes. Review of the therapy indicates that insertion of a pericardial tube under direct vision is the safest and most effective means of treating pneumopericardium in infants. These data also suggest that PIP is more important than PEEP in predisposing neonates with respiratory distress syndrome to pneumopericardium.