Inner-Ear DCS Versus Arterial Gas Embolism After a Rapid Ascent
A 29-year-old recreational diver makes a panic ascent from 20 m after his regulator free-flows. He surfaces in under a minute, sputtering, and is pulled aboard. Within 10 minutes he has vertigo, vomiting, right-sided hearing loss, and tinnitus. Thirty minutes later he is confused and has left arm weakness. He has no chest pain and no hemoptysis. He is 40 minutes from a chamber and is currently on a boat 15 minutes from shore. His buddy reports he was 'fine' at depth and had no prior ear problems.
1. Distinguish the two competing diagnoses and explain why the distinction matters clinically.
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Two diagnoses fit:
- Inner-ear DCS - vertigo, hearing loss, tinnitus after a dive; typically from bubble formation in the labyrinth, often with other DCS features.
- Arterial gas embolism (AGE) - from pulmonary barotrauma during the rapid ascent; bubbles enter the arterial circulation and can cause stroke-like deficits (confusion, hemiparesis), and can also lodge in the inner ear.
The distinction matters because AGE is treated with urgent recompression, often to 6 ATA (US Navy Treatment Table 6A), and the presentation of inner-ear symptoms plus cortical signs in a diver who made a rapid ascent strongly favors AGE. Inner-ear DCS alone would not explain the hemiparesis. Both are treated with recompression, so the decision to treat is the same; the distinction changes the treatment table and the urgency.
2. What is your immediate management on the boat, and what is your transport and chamber plan?
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Immediate management:
- 100% oxygen by tight-fitting mask (non-rebreather), supine with head slightly down and legs elevated if tolerated - the Trendelenburg position is traditional for AGE; keep the patient flat and avoid straining.
- IV access, treat vomiting (antiemetic), keep the patient calm and warm, and monitor airway.
- Do not delay for imaging - the diagnosis is clinical and the clock matters.
Transport: helicopter or fast boat directly to the chamber, not to a hospital without hyperbaric capability. Notify the chamber en route so a Table 6A can be started on arrival. If air transport is used, keep the patient on oxygen and avoid high altitude if possible; pressurize the cabin or fly low.
3. The patient's symptoms partially resolve with oxygen before arrival. Does that change your decision to recompress?
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No. Partial or complete resolution of symptoms with surface oxygen is common in AGE and does not mean the patient is treated. Residual bubbles and endothelial injury can cause delayed deterioration, and recurrence after apparent recovery is well described.
Recompression is still indicated, and the patient should be treated even if asymptomatic on arrival - the standard is to treat the presumed AGE with a hyperbaric table and observe. Document the pre-oxygen and post-oxygen exam carefully, because improvement with oxygen is itself supportive of the diagnosis.