injuries poisoning
Cardiac Tamponade
Introduction
Cardiac tamponade is accumulation of blood in the pericardial sac of sufficient volume and pressure to impair cardiac filling. Patients typically have hypotension, muffled heart tones, and distended neck veins. Diagnosis is made clinically and often with bedside echocardiography. Treatment is immediate pericardiocentesis or pericardiotomy. (See also Overview of Thoracic Trauma .) Fluid in the pericardial sac can impair cardiac filling, leading to low cardiac output and sometimes Shock and death. If fluid accumulates slowly (eg, due to chronic inflammation), the pericardium can stretch to accommodate up to 1 to 1.5 L of fluid before cardiac output is compromised. However, with rapid fluid accumulation, as occurs with traumatic hemorrhage, as little as 150 mL may cause tamponade. In trauma, the cause is more often a penetrating rather than blunt mechanism. The wound is often medial to the nipples (for anterior wounds) or the scapulae (for posterior wounds). Tamponade due to blunt trauma involves cardiac chamber rupture, which is typically fatal before patients can be brought for treatment. 