(See also Overview of Diving Injuries Overview of Diving Injuries More than 1000 diving-related injuries occur annually in the United States; > 10% are fatal. Similar injuries can befall workers in tunnels or caissons (watertight retaining structures used... read more and Overview of Barotrauma Overview of Barotrauma Barotrauma is tissue injury caused by a pressure-related change in body compartment gas volume in air-containing areas. During ascent, gas expansion can affect the lungs and gastrointestinal... read more .)
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 Pneumothorax Pneumothorax is air in the pleural space causing partial or complete lung collapse. Pneumothorax can occur spontaneously or result from trauma or medical procedures. Diagnosis is based on clinical... read more
(causing dyspnea, chest pain, and unilateral decrease in breath sounds) Pneumomediastinum Pneumomediastinum Pneumomediastinum is air in mediastinal interstices. The main causes of pneumomediastinum are Alveolar rupture with dissection of air into the interstitium of the lung with translocation to... read more
(causing sensation of fullness in the chest, neck pain, pleuritic chest pain that may radiate to the shoulders, dyspnea, coughing, hoarseness, and dysphagia).
The most common form of pulmonary barotrauma is pneumomediastinum. Mediastinal air can track into the neck, causing subcutaneous emphysema detectable as crepitation, and voice changes. A crackling sound rarely heard over the heart ("mediastinal crunch," 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 Pneumothorax (Tension) Tension pneumothorax is accumulation of air in the pleural space under pressure, compressing the lungs and decreasing venous return to the heart. (See also Overview of Thoracic Trauma.) Tension... read more , 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 Arterial Gas Embolism Arterial gas embolism is a potentially catastrophic event that occurs when gas bubbles enter or form in the arterial vasculature and occlude blood flow, causing organ ischemia. Arterial gas... read more , which is particularly dangerous when it involves the brain, but can also affect other organs (eg, spinal cord, heart, skin, kidneys, spleen, gastrointestinal tract).
Compression of the lungs may occur during very deep descent in breath-hold diving; compression may rarely decrease lung volume below residual volume, causing mucosal edema, vascular engorgement, pulmonary edema, and hemorrhage, which manifest clinically as dyspnea and hemoptysis on ascent.
Diagnosis of Pulmonary Barotrauma
Chest imaging
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.
If patients have any neurologic deficits found on neurologic examination, arterial gas embolism to the brain should be suspected.
Treatment of Pulmonary Barotrauma
100% oxygen
Sometimes tube thoracostomy
Suspected tension pneumothorax is treated with needle decompression followed by tube thoracostomy How To Do Tube and Catheter Thoracostomy Surgical tube thoracostomy is insertion of a surgical tube into the pleural space to drain air or fluid from the chest. Pneumothorax that is recurrent, persistent, traumatic, large, under tension... read more 
. 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 Mediastinoscopy and Mediastinotomy Mediastinoscopy is a procedure in which an endoscope is introduced through the suprasternal notch into the mediastinum to allow visualization of it. Mediastinotomy is surgical opening of the... read more is required to relieve tension pneumomediastinum.
Prevention of Pulmonary Barotrauma
Prevention of pulmonary barotrauma is usually the top priority. Proper ascent timing and techniques are essential. Patients at high risk for pneumothorax Pneumothorax Pneumothorax is air in the pleural space causing partial or complete lung collapse. Pneumothorax can occur spontaneously or result from trauma or medical procedures. Diagnosis is based on clinical... read more during diving include those with pulmonary bullae, Marfan syndrome Marfan Syndrome Marfan syndrome consists of connective tissue anomalies resulting in ocular, skeletal, and cardiovascular abnormalities (eg, dilation of ascending aorta, which can lead to aortic dissection)... read more 
, chronic obstructive pulmonary disease Chronic Obstructive Pulmonary Disease (COPD) Chronic obstructive pulmonary disease (COPD) is airflow limitation caused by an inflammatory response to inhaled toxins, often cigarette smoke. Alpha-1 antitrypsin deficiency and various occupational... read more 
, or previous spontaneous pneumothorax. Such individuals should not dive or work in areas of compressed air. Patients with asthma Asthma Asthma is a disease of diffuse airway inflammation caused by a variety of triggering stimuli resulting in partially or completely reversible bronchoconstriction. Symptoms and signs include dyspnea... read more 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 Pneumomediastinum Pneumomediastinum is air in mediastinal interstices. The main causes of pneumomediastinum are Alveolar rupture with dissection of air into the interstitium of the lung with translocation to... read more after a dive should be referred to a diving medicine specialist for assessment of risks of future dives.
After COVID-19 infection, some people develop lung pathology (such as bullae) that could increase their risk for pulmonary barotrauma while diving. Proposed guidelines (1, 2 Prevention references Barotrauma is tissue injury caused by a pressure-related change in body compartment gas volume. Factors increasing risk of pulmonary barotrauma include certain behaviors (eg, rapid ascent, breath-holding... read more ) recommend spirometry and chest imaging for anyone who has had respiratory or cardiac symptoms (including chest pain, palpitations, significant cough, or dyspnea) due to COVID-19 infection
Prevention references
1. Sadler C, Alvarez Villela M, Van Hoesen K, et al: Diving after SARS-CoV-2 (COVID-19) infection: Fitness to dive assessment and medical guidance. Diving Hyperb Med 50(3):278-287, 2020. doi 10.28920/dhm50.3.278-287
2. Sadler C, Alvarez-Villela M, Van Hoesen K, et al: Diving after COVID-19: An update to fitness to dive assessment and medical guidance. Diving Hyperb Med 52(1):66-67, 2022. doi: 10.28920/dhm52.1.66-67
Key Points
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.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
Krzyżak J, Korzeniewski K: Medical assessment of fitness to dive. Part I. Int Marit Health 72(1):36-45, 2021. doi: 10.5603/MH.2021.0005
Krzyżak J, Korzeniewski K: Medical assessment of fitness to dive. Part II. Int Marit Health 72(2):115-120, 2021. doi: 10.5603/MH.2021.0005
Divers Alert Network: 24-hour emergency hotline, 919-684-9111
Duke Dive Medicine: Physician-to-physician consultation, 919-684-8111
