A tension pneumothorax is a unilateral progressive collection of air in the pleural space. If not treated, it results in increasing intrapleural pressures, shifting of intrathoracic structures, hypoxemia, and death. It occurs from a one-way air leak into the pleural cavity from the airway conduits, the lung, or the thoracic wall. The air leak causes air to enter the pleural cavity and become trapped, without a method of egress. Rapid decompression of the tension pneumothorax with a catheter-over-the-needle is known as a needle thoracostomy and can be lifesaving.
A tension pneumothorax is an immediate life-threatening condition that requires prompt recognition and treatment to prevent the patient's imminent demise. The diagnosis must be suspected based upon the patient's prior medical history, the mechanism of injury, physical examination findings, and a patient in extremis. Importantly, treatment must not be delayed to obtain further diagnostic testing (e.g., chest radiograph). These patients most often present with acute and dramatic cardiopulmonary compromise, which may be manifest by a combination of the following signs and symptoms: respiratory distress, chest pain, air hunger, hypotension, tachycardia, diaphoresis, unilateral absence of or decrease in breath sounds, hyperresonance to percussion, increased central venous pressure, hypoxemia, cyanosis, deviation of the cardiac point of maximal impulse, and tracheal deviation.
The most common cause of a tension pneumothorax is mechanical ventilation with positive pressure in a patient with a visceral pleural injury.1 A tension pneumothorax is present in 50% of ventilator-associated pneumothoraces.2 When this occurs in intensive care unit (ICU) patients, they often have minimal functional reserve. To further cloud the issue, they are frequently on other supports (i.e., inotropic agents, complex ventilator settings, etc.), making their physical examination difficult and confusing. They may also have a number of other coexisting factors that are making them unstable. This group of patients has a particularly disastrous course if a tension pneumothorax develops. Rapid diagnosis and treatment are imperative.3
The placement of a central venous catheter has been associated with the development of a pneumothorax. The incidence of this is approximately 3% to 6% with use of the subclavian approach. A tension pneumothorax may be delayed in approximately 0.4% of attempts to gain central venous access. In one case report, a patient developed a tension pneumothorax while under general anesthesia 10 days after the placement of a subclavian central venous line.4
A tension pneumothorax may also occur in the setting of blunt or penetrating trauma of the lung. It may occur uncommonly following a tracheobronchial or esophageal injury. It may complicate a simple pneumothorax if the parenchymal lung leak does not seal spontaneously. In this case, the site of the lung injury acts as a one-way valve, allowing air entry into the pleural space and not allowing it to escape. Occasionally, chest wall defects may result in a tension pneumothorax if the wound is completely covered by an occlusive dressing or if the wound itself acts ...