Decompression Sickness and Arterial Gas Embolism

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Updated July 2026  |  More ICU nursing guides →

Diving injuries, collectively called dysbarism, arise from the physics of breathing compressed gas under pressure and then returning to the surface. Under pressure, extra nitrogen dissolves into the body's tissues; if the diver ascends too fast, that nitrogen comes out of solution as bubbles — like opening a shaken soda. Those bubbles cause decompression sickness (DCS, "the bends"). A separate, more immediate catastrophe, arterial gas embolism (AGE), happens when a diver holds their breath on ascent and lung gas is forced into the arterial circulation. Coastal, resort, and military-adjacent hospitals see these, and the treatment is time-sensitive.

Two injuries, one gas problem

It helps to hold the two entities apart even though their treatment overlaps.

The timing is a clue. AGE strikes within minutes of surfacing and looks like a sudden stroke or cardiac arrest. DCS more often declares itself over minutes to hours after the dive — joint pain and fatigue in milder cases, or neurologic deficits (numbness, weakness, difficulty urinating, unsteadiness) in serious ones. Any new neurologic symptom after a dive is treated as serious until a diving-medicine expert says otherwise.

Oxygen and position: what the nurse does first

Two nursing interventions matter enormously before the patient ever reaches a hyperbaric chamber. First, give 100% oxygen by non-rebreather at high flow. High-concentration oxygen creates a diffusion gradient that helps wash inert nitrogen out of the bubbles and shrink them, and it treats the tissue hypoxia the bubbles cause — this is a genuine treatment, not just supportive care, and it should be started as early as possible and continued during transport. Second, lay the patient flat (supine) and keep them there; the historical head-down (Trendelenburg) position is no longer recommended because it can worsen cerebral edema, but keeping the patient horizontal helps and avoiding upright positioning is important.

Alongside these, give IV fluids for the dehydration that accompanies diving and bubble injury, keep the patient warm, and monitor neuro status closely. Document a careful dive history — depth, bottom time, ascent rate, number of dives, and time since surfacing — because the diving-medicine team needs it and the nurse is often who captures it.

Hyperbaric oxygen: the definitive treatment

The definitive treatment for significant DCS and for AGE is hyperbaric oxygen therapy (HBOT) — recompression in a chamber that re-pressurizes the body to shrink the bubbles back into solution while delivering high-concentration oxygen, then slowly decompresses on a controlled schedule. The nurse's role is to stabilize the patient, get them on 100% oxygen and fluids, and facilitate rapid referral to a chamber; earlier recompression generally means better neurologic recovery. Some deficits resolve completely with prompt treatment; delay allows permanent injury.

The arterial gas embolism emergency

AGE is the one that arrests patients on the dock. A diver who surfaces and immediately collapses, seizes, or develops sudden stroke-like deficits is a gas-embolism emergency: this is standard resuscitation — airway, breathing, circulation — with 100% oxygen, supine positioning, and the fastest possible route to a hyperbaric chamber. Because gas can enter the coronary and cerebral arteries, cardiac arrest and stroke-like presentations both occur, and the underlying cause is not something ordinary ACLS reverses — recompression is what treats the bubbles.

For the neurologic monitoring these patients need, see neuro checks and the Glasgow Coma Scale; the sudden-collapse presentation overlaps with acute stroke recognition. Related environmental emergencies: high-altitude illness and marine envenomation.