Definition:—Air or gas in the pericardium.

Etiology:—Puncture of the pericardium, simultaneously with rupture of the chest wall or lung structure, may result in the admission of air into the pericardial sac. Diseases that produce cavities in the lungs may perforate also the enveloping membrane of the lung and heart, and admit air to this sac. It has also followed pyothorax and gastric ulcer.

Symptomatology:—Pneumopericardium, clinically, does not exist independent of some effusion, either serous, purulent or sanguineous. With the exception that the heart oppression is greater and there is more difficulty of breathing, the symptoms are the same as those of pericarditis, with effusion. The physical signs, however, are of diagnostic value. Instead of diffused dulness there is resonance on percussion over the heart, with occasionally a rasping, crackling metallic friction sound, sometimes known as the "water wheel" sound, resembling the churning or splashing of fluid, due to the commingling of the fluid and gas in the cavity. This, accompanied with marked disturbance of the heart's action, and increasing feebleness, is a diagnostic indication of much value. It should be distinguished from the fluid sounds present when the fluid content of the large lung cavity is agitated by action of the heart.

Prognosis:—The prognosis is unfavorable. But few cases recover; death usually occurs within a few days.

Treatment:—While the symptoms may be ameliorated by specific measures, the real treatment is purely surgical, and this course must not be resorted to unless conditions are in every way favorable. It is usually only applicable in traumatic cases. Where chronic disease, with ulceration, is the cause of this condition surgical or medicinal measures are of no avail.

The Eclectic Practice of Medicine with especial reference to The Treatment of Disease, 1910, was written by Finley Ellingwood, M.D.