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Cardiac tamponade is a relatively rare condition. If a
pericardial effusion compromises hemodynamics, pericardiocentesis
can be lifesaving. The cause of cardiac tamponade may be
determined by fluid analysis after pericardiocentesis (Table
37-1).
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In a small study of medical cardiac tamponade, the mean volume drained
was 593 ± 313 mL. When the primary cause was malignancy, nearly
80% of the patients had a 1-year mortality.1
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Maintain a high degree of suspicion of cardiac tamponade for
oncology patients who fit the clinical signs and symptoms of tamponade.
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Blunt cardiac rupture is rare, occurring approximately once in
2400 blunt trauma patients. Of this subgroup, 89% arrive
alive to the ED.2 Those who arrive alive may benefit
from a bedside US examination to detect a traumatic effusion. Tamponade
may require a temporizing pericardiocentesis while the patient is
prepared for definitive surgical repair.
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In a South African study, mortality from gunshot wounds compared
to stab wounds was 81% and 15.6%, respectively.3 This
comparison underlines the probability that patients with stab wounds
to the heart are more likely to survive to the ED and may benefit
from pericardiocentesis.
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The pericardium is a fibrocollagenous sac covering the heart
that contains a small amount of physiologic serous fluid. The fibrocollagenous
pericardium has elastic properties and will stretch in response
to increases in intrapericardial fluid. Accumulation of fluid that
exceeds the stretch capacity of the pericardium precipitates hemodynamic
compromise and results in pericardial tamponade.
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The initial portion of the pericardial volume–pressure
curve is flat, so early on, relatively large increases in volume
result in comparatively small changes in intrapericardial pressure.
The pericardium becomes less elastic as the slope of ...