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lung, but it also compresses the contralateral lung ( Fig. 115.2 ). These patients
may present in severe respiratory distress with decreased breath sounds on the
side of the pneumothorax. There is also a shift of the mediastinal structures to the
contralateral side. Two-thirds of the blood supply to the body is returned to the
heart via the inferior vena cava. Because the inferior vena cava is relatively fixed
in place as it passes through the diaphragm and cannot shift as much as the
superior vena cava, venous return to the heart is reduced.

FIGURE 115.2 Tension pneumothorax with a mediastinal shift.

Some patients with a pneumothorax or hemothorax demonstrate tension
physiology: tachycardia and peripheral vasoconstriction. If left untreated, this will
progress to shock. Initial treatment for tension physiology consists of needle
decompression. An immediate release of air should be noted with tension
pneumothorax and the patient’s hemodynamic status should improve. The needle
decompression is only a temporizing measure and must be followed by tube
thoracostomy.
Open Pneumothorax
An open pneumothorax is the result of penetrating trauma. There is a direct
connection between the pleural space and the atmosphere, impeding ventilation.
As in a bronchial tear or lung parenchymal injury, air may enter but not leave the
pleural space, creating a ball-valve effect. Initial treatment includes placement of