Overexpansion and alveolar rupture can occur when breath-holding occurs (usually while breathing compressed air) during ascent, particularly rapid ascent. The result can be pneumothorax (causing dyspnea, chest pain, and unilateral decrease in breath sounds) or pneumomediastinum (causing sensation of fullness in the chest, neck pain, pleuritic chest pain that may radiate to the shoulders, dyspnea, coughing, hoarseness, and dysphagia). Pneumomediastinum may cause crepitation in the neck, due to associated subcutaneous emphysema, and a crackling sound may rarely be heard over the heart during systole (Hamman sign). Air can sometimes track caudad into the peritoneal cavity (falsely suggesting a ruptured viscus and the need for laparotomy), but it does not typically cause peritoneal signs. Tension pneumothorax, although rare with barotrauma, can cause hypotension, distended neck veins, hyperresonance to percussion, and, as a late finding, tracheal deviation. Alveolar rupture can allow air into the pulmonary venous circulation with subsequent arterial gas embolism.
During very deep breath-hold diving, compression of the lungs during descent may rarely lead to a decrease in volume below residual volume, causing mucosal edema, vascular engorgement, and hemorrhage, which manifest clinically as dyspnea and hemoptysis on ascent.
Patients require a neurologic examination for signs of brain dysfunction due to arterial gas embolism.
Chest x-ray is done to look for signs of pneumothorax or pneumomediastinum (radiolucent band along the cardiac border). If chest x-ray is negative but there is strong clinical suspicion, then chest CT, which may be more sensitive than plain film x-rays, may be diagnostic. Ultrasound may also be useful for rapid bedside diagnosis of pneumothorax. Pneumoperitoneum without a ruptured viscus should be suspected when pneumoperitoneum is present without peritoneal signs.
Suspected tension pneumothorax is treated with needle decompression followed by tube thoracostomy. If a smaller (eg, 10 to 20%) pneumothorax is present and there is no sign of hemodynamic or respiratory instability, the pneumothorax may resolve when high-flow 100% oxygen is given for 24 to 48 hours. If this treatment is ineffective or if a larger pneumothorax is present, tube thoracostomy (using a pigtail catheter or small chest tube) is done.
No specific treatment is required for pneumomediastinum; symptoms usually resolve spontaneously within hours to days. After a few hours of observation, most patients can be treated as outpatients; high-flow 100% oxygen is recommended to hasten resorption of extra-alveolar gas in these patients. Rarely, mediastinotomy is required to relieve tension pneumomediastinum.
Prevention of pulmonary barotrauma is usually the top priority. Proper ascent timing and techniques are essential. Patients at high risk for pneumothorax during diving include those with pulmonary blebs or bullae, Marfan syndrome, chronic obstructive pulmonary disease, or previous spontaneous pneumothorax. Such individuals should not dive or work in areas of compressed air. Patients with asthma may be at risk of pulmonary barotrauma, although many people with asthma can dive safely after they are evaluated and treated appropriately. Patients with pneumomediastinum after a dive should be referred to a diving medicine specialist for assessment of risks of future dives.
Although rare, pulmonary barotrauma can result in tension pneumothorax, which must be immediately decompressed.
Examine all patients who have pulmonary barotrauma for signs of brain dysfunction, which suggests arterial gas embolism.
Treat all patients with suspected pulmonary barotrauma with 100% oxygen pending diagnostic testing.