Barotrauma on ascent in diving

On ascent, barotrauma risk results from increasing gas volume within a trapped air space; relative over-pressurisation can cause problems such as tympanic membrane rupture, ear pain and vertigo. Management of local air trapping on ascent is as for barotrauma on descent.

Pulmonary barotrauma is a serious event occurring on ascent, when expanding gas trapped in the lung causes alveoli to rupture. Air trapping can result in:

  • arterial gas embolism
  • pneumothorax
  • pneumomediastinum.

Prevention of pulmonary barotrauma includes:

  • medical screening to ensure the diver has no conditions that predispose to lung injury with expanding air pressure; see Contraindications to scuba diving
  • good diving practice of a controlled ascent rate with exhalation.

Arterial gas embolism results from ruptured alveoli allowing air bubbles to enter the pulmonary capillaries and then the systemic circulation. Typically, arterial gas embolism develops on ascent, or immediately after a diver surfaces; it presents as a sudden loss of consciousness and circulatory collapse. Any sudden loss of consciousness or neurological presentations within 10 minutes of a diver surfacing should be considered arterial gas embolism. Suspected arterial gas embolism is an emergency; it can be clinically indistinguishable from the neurological effects of decompression sickness. The treatment is identical—urgent referral for hyperbaric oxygen therapy. Refer any diver with loss of consciousness or neurological presentations that occur within 10 minutes of surfacing for emergency hyperbaric oxygen recompression treatment. through the Diving Emergency Service (telephone 1800 088 200 within Australia) or through local emergency services. See also Management of decompression sickness.

Note: Refer any diver with loss of consciousness or neurological presentations that occur within 10 minutes of surfacing for emergency hyperbaric oxygen recompression treatment through the Divers Emergency Service (telephone 1800 088 200 within Australia) or through local emergency services.

Pneumothorax is uncommon in diving, although more likely in the presence of underlying lung disease or previous pneumothorax. It can present as chest pain, shortness of breath and, rarely, haemoptysis. All divers presenting with chest pain or shortness of breath require a detailed assessment including 12-lead electrocardiogram (ECG) and chest X-ray. See Pneumothorax for management. A decompensated (tension) pneumothorax can present with more severe chest pain and dyspnoea, tachycardia, hypotension, cyanosis and distended neck veins; it may progress to cardiovascular collapse and respiratory arrest.

Note: All divers with chest pain or shortness of breath require an electrocardiogram and chest X-ray.

Pneumomediastinum is possible; it may present with pleuritic chest pain radiating to the shoulders, dyspnoea, coughing and dysphagia. Palpable crepitation due to subcutaneous emphysema might be found. Tension pneumomediastinum is rare, presenting with all the symptoms of pneumomediastinum, but progressing rapidly to severe respiratory distress and cardiovascular collapse, due to increased intrathoracic pressure obstructing venous return to the heart.

Note: Consider tension pneumothorax or tension pneumomediastinum in all divers with severe respiratory distress.

Minimally symptomatic pneumomediastinum and small pneumothoraces usually only require conservative management with supplemental oxygen, rest and analgesia. Close observation and daily chest X-ray can be used to monitor spontaneous resolution. Tension pneumothorax and tension pneumomediastinum are managed with a midclavicular intercostal needle thoracostomy followed by formal intercostal tube thoracostomy.