A tension pneumothorax is a unilateral progressive collection of air in the pleural space (Figures 50-1 and 50-2). 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 is lifesaving.
A right-sided tension pneumothorax. The traditional site for a needle thoracostomy is the second intercostal space in the midclavicular line.
Radiograph of a left-sided tension pneumothorax with no mediastinal shift. (Used with permission from reference 22.)
A tension pneumothorax is an immediate life-threatening condition that requires prompt recognition and treatment to prevent the patient’s imminent demise. The diagnosis may be suspected based on 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.
ANATOMY AND PATHOPHYSIOLOGY
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 supportive interventions (e.g., inotropic agents, complex ventilator settings), making their physical examination challenging and unreliable. 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, but this has been shown to decrease significantly with the use of ultrasound.4 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 ...