PERICARDIAL EFFUSIOH



The hemodynamic effects of fluid in the peri­cardial cavity depend on the volume and rate of fluid accumulation. Because the pericardium is not compliant, an increase in pericardial effusion that occurs acutely may cause a rapid rise in in-trapericardial pressure. If the accumulation of fluid is more gradual, the pericardium may ac­commodate, and the intrapericardial pressure in­crease is not as great for any given amount of per­icardial fluid. Small increases in the volume of pericardial fluid may have little hemodynamic ef­fect at first, but subsequent small increases may result in a rapid rise in intrapericardial pressure,accounting for the rapid clinical deterioration of patients with stable pericardial effusion.

The patient with pericardial effusion and he­modynamic compromise has dyspnea, tachycar­dia, distended jugular veins, and a rapid thready pulse. Rales typical of pulmonary edema are ab­sent. Dullness, increased fremitus, and bronchial breath sounds posteriorly below the angle of the left scapula due to compression of the left lower lung by the pericardium (Ewart’s sign) may be present. The precordium often is quiet to auscul­tation, and the apical impulse frequently is not palpable. Kussmaul’s sign, an increase in jugular venous pressure with inspiration, is unusual in pericardial effusion or tamponade. When cardiac tamponade results, pulsus paradoxus, character­ized by a decrease in the systolic blood pressure of more than 10 mm Hg with’ normal inspiration, frequently is present. The paradoxical pulse often can be noted by marked weakening or disappear ance of a peripheral pulse during inspiration. Par­adoxical pulse is not diagnostic of pericardial tamponade and can occur in chronic lung disease, acute asthma, and severe congestive heart failure.

Anv cause of acute pericarditis can lead to per­icardial effusion. The electrocardiogram may be normal, may demonstrate low voltage, or may re­veal ST and T wave changes typical of pericar­ditis. Electrical alternans, a variation in voltage of P. QRS, and T waves in alternate beats, may occur in patients with large effusions. The chest x-ray may show an enlarged “water bottle” cardiac sil­houette, but if the pericardial effusion has devel­oped rapidly, the chest x-ray may show a normal heart size. Definitive diagnosis of pericardial ef­fusion is usually obtained by echocardiography. Cardiac catheterization shows pulsus paradoxus, equalization of diastolic pressures throughout the heart, elevated systemic venous pressure, and normal or reduced cardiac output with reduced stroke volume.

The management of pericardial effusion with­out tamponade is similar to that of acute pericar­ditis. Patients with acute significant pericardial effusions should be hospitalized to monitor for impending tamponade. If tamponade occurs, the pericardium should be drained by pericardiocen­tesis or surgery. Patients with cardiac tamponade and hypotension should receive intravenous vol­ume (and possibly isoproterenol) to optimize car­diac performance until pericardial drainage can be performed. Diuresis is contraindicated.
The pericardial fluid should be examined mi­croscopically for bacteria, cells, cytology, culture, glucose, and protein content. An indwelling cath­eter or drain is sometimes left in place for sub­sequent drainage of pericardial fluid or chemo­therapy instillation.