Barotrauma

Barotrauma (from the Ancient Greek βάρος — weight, pressure, and τραῦμα — wound) is a physical injury that occurs when tissues are damaged due to a difference in pressure between a gas-filled cavity in the body and the surrounding environment. This injury happens when gas within a cavity cannot freely equalize with external pressure.

Boyle’s law explains the underlying mechanism: as external pressure changes, the volume of gas in a closed cavity adjusts accordingly. Gas expands when pressure decreases and contracts when it increases, stretching or compressing the surrounding tissues, which may ultimately lead to rupture.

Aetiology and Pathophysiology

Barotrauma can occur in any situation where environmental pressure changes rapidly.

The most common scenarios include:

• Diving and underwater descents: Even small changes in depth can produce significant pressure differences, making diving a classic cause of barotrauma.
• Air travel: Cabin pressure changes during ascent and descent can create similar effects.
• Mechanical ventilation: Excessive airway pressure from ventilators can injure the lungs, a phenomenon known as volutrauma.
• Blast exposure: Explosive pressure waves can cause sudden and severe tissue injury.

The pathogenesis of barotrauma is related to the inability of gas-filled cavities (e.g., the middle ear, paranasal sinuses, lungs) to equalize with external pressure. This often occurs when the channels connecting these cavities, such as the Eustachian tube, sinus ostia, or airways, are blocked.

Clinical Significance by Location

Symptoms of barotrauma depend entirely on which organ is affected.

• Ear barotrauma (barotitis or aerotitis):
  • Description: The most common form of barotrauma. It develops when the Eustachian tube is blocked, for example, due to a cold or adenoidal hypertrophy.
  • Symptoms: Patients typically experience sudden, sharp ear pain, a sensation of fullness, hearing loss, or tinnitus. In severe cases, the tympanic membrane may rupture, bleeding can occur in the middle ear (hemotympanum), or the inner ear may be damaged, resulting in a perilymphatic fistula.
• Sinus barotrauma (barosinusitis, sinus squeeze, or aerosinusitis):
  • Description: This occurs when sinus ostia are obstructed.
  • Symptoms: It usually presents with intense, acute pain in the forehead (frontal sinus) or cheeks (maxillary sinus). Epistaxis may also occur in some cases.
• Pulmonary barotrauma:
  • Description: The most severe, potentially life-threatening form, typically seen in divers. It occurs when expanding gas in the lungs ruptures alveoli during ascent while holding the breath.
  • Complications: Patients may develop pneumothorax or subcutaneous emphysema. In severe cases, arterial gas embolism can occur, where air bubbles enter the bloodstream and may lead to stroke or myocardial infarction.
• Dental barotrauma (barodontalgia): Pain in a tooth caused by air trapped under a filling that expands during pressure changes.

Prevention and Treatment

Prevention is the cornerstone of managing barotrauma. Individuals should avoid flying or diving with an acute upper respiratory infection or sinus inflammation. During changes in pressure, such as when flying or diving, it is important to actively use techniques to equalize pressure, such as swallowing, yawning, chewing, or the Valsalva maneuver. Treatment depends on the severity and location of the injury. Mild forms affecting the ear or sinuses often resolve spontaneously or with the aid of decongestants and anti-inflammatory medications. Pulmonary barotrauma complicated by gas embolism is a medical emergency, requiring immediate oxygen therapy and hyperbaric treatment.