ECMO-/ECLS

tenderness and subcutaneous emphysema. There is increased risk of
intrathoracic damage with penetrating injuries, particularly hemothorax and
pneumothorax. There should be a low threshold to perform chest tube
thoracostomy, if the clinical situation warrants.
The heart, esophagus, and tracheobronchial tree reside in the anterior
“cardiac box” and penetrating wounds over the precordium or traversing
missiles through this area should prompt concern for cardiac injury. The
boundaries of the box are the clavicles superiorly, the nipples laterally, and the
costal margin inferiorly. As part of the physical exam, the patient should be
examined for signs of cardiac tamponade. Three classical signs, known as
Beck’s triad, include hypotension, distended neck veins, and muffled heart
sounds. Additionally, pulsus paradoxus, or a drop in 10mm Hg of arterial
pressure with inspiration, may be seen. Sonographic examination should also
be done at the bedside to assess for pericardial effusion. Confirmation of
cardiac injury or hemodynamic instability warrants emergent thoracotomy. In
cases of severe tamponade, pericardiocentesis may be done as a temporizing
measure prior to the operating room.
The posterior “cardiac box” is occupied by the tracheobronchial tree,
esophagus, and aorta. Physical exam findings may be non-specific for injuries
in this area of the cardiac box. Patients may present with hoarseness, chest
wall crepitance, or substernal tenderness. However, the location of the
penetration wound and knowledge of the cardiac box may be the only clue to