Mask squeeze

Background

• The air in the mask decreases in volume during a dive, and that causes negative pressure on the covered area of the face.
• Occurs when air is not added to facemask during scuba diving descent to equalize the negative pressure.

Barotrauma Types

• Otic barotrauma
• Pulmonary barotrauma
• Sinus barotrauma
• Mask squeeze
• Barodentalgia (trapped dental air causing squeeze)

Diving Physiology

• Pascals Law applies to the diving body (without air filled areas such as lungs) states that the pressure applied to any part of the enclosed liquid will be transmitted equally in all directions through the liquid.
• Boyles Law applies to the diving body's air filled areas such as lungs, sinuses, middle ear, and states that the volume and pressure of a gas at a given temperature are inversely related.
  • At 2 ATA (10m/33ft) a given gas would be 1/2 it's volume, at 3 ATA (20m/66ft) it would be 1/3 it's volume and so on.

Boyle's Law

Clinical Features

Mild barotrauma to a diver caused by mask squeeze

• Facial bruising
• Conjunctival Injection/hemorrhage
• Retrobulbar hemorrhage if severe

Differential Diagnosis

Diving Emergencies

• Barotrauma of descent
  • Otic barotrauma
  • Pulmonary barotrauma
  • Sinus barotrauma
  • Mask squeeze
  • Barodentalgia (trapped dental air causing squeeze)
• Barotrauma of ascent
  • Pulmonary barotrauma (pulmonary overpressurization syndrome)
  • Decompression sickness (DCS)
  • Arterial gas embolism
  • Alternobaric vertigo
  • Facial baroparesis (Bells Palsy)
• At depth injuries
  • Oxygen toxicity
  • Nitrogen narcosis
  • Hypothermia
  • Contaminated gas mixture (e.g. CO toxicity)
  • Caustic cocktail from rebreathing circuit

Evaluation

• Clinical diagnosis, most often benign, with subconjunctival hemorrhage common.
• Rule out rare complications such as hyphema, orbital hematoma, retrobulbar hematoma
  • May warrant CT orbit if exam concerning for ocular compartment syndrome or retrobulbar hematoma
  • Check IOP

Management

• If presentation concerning for ocular compartment syndrome with Retrobulbar hemorrhage, orbital hematoma, hyphema
  • These patients should be treated in usual manner (ophtho, lateral Canthotomy if needed, CT evaluation) if clear signs of mask squeeze and related symptoms instead of jumping to hyperbaric treatments.
• If benign presentation
  • Resolves over a few days to a week
  • Cold compresses and analgesics may help

Disposition

• Outpatient

See Also

• Scuba diving emergencies