Decompression sickness occurs when dissolved inert gas comes out of solution and forms bubbles in the body during or after a dive. Arterial gas embolism occurs when gas enters the arterial circulation, often after lung overexpansion during ascent. Both are serious diving emergencies, but they differ in how gas causes harm.
The symptoms can overlap, so appearance alone may not reliably distinguish them. Understanding the mechanisms behind decompression sickness vs. arterial gas embolism helps explain why dive history, timing and prompt medical assessment matter—and why either suspected condition warrants urgent care.
| Criterion | Decompression sickness | Arterial gas embolism |
|---|---|---|
| Underlying process | Dissolved gas forms bubbles as pressure falls | Gas enters the arterial circulation |
| Typical timing clue | May begin after surfacing, sometimes later | Often sudden during ascent or shortly after surfacing |
| Possible presentation | Pain, sensory change, weakness, or other neurological symptoms | Sudden neurological symptoms, including weakness or loss of consciousness |
| Can symptoms overlap? | Yes | Yes |
| Response to suspected symptoms | Urgent medical evaluation | Urgent medical evaluation |
What distinguishes decompression sickness from arterial gas embolism?
Decompression sickness (DCS) involves inert-gas bubbles forming from gas dissolved in the body as pressure falls during or after a dive, whereas arterial gas embolism (AGE) occurs when gas enters the arterial circulation, commonly after lung overexpansion during ascent. Both are pressure-related diving emergencies, but they arise through different processes.
- DCS: The defining process is bubble formation from dissolved inert gas during or after the pressure decrease.
- AGE: The defining process is gas entering arterial blood; lung overexpansion during ascent is a common route.
The distinction is about how gas reaches the circulation, not simply whether a diver has bubbles: DCS begins with inert gas coming out of solution, while AGE involves gas entering the arteries. These descriptions explain the mechanisms but do not, on their own, establish a diagnosis for an individual diver.
Limits of the available evidence
The supplied research contains no dive-medicine source, so it cannot substantiate detailed diagnostic criteria, symptom comparisons, timing rules or treatment protocols for DCS and AGE. For that reason, no numerical thresholds, test criteria or treatment instructions can be responsibly given here; suspected cases require assessment by qualified medical professionals.
When do symptoms appear after a dive?
Symptoms of arterial gas embolism (AGE) classically begin rapidly during ascent or shortly after surfacing, while decompression sickness (DCS) can start after surfacing and may emerge later. The timing differs in typical presentations, but there is no exact onset window or percentage available here to define either condition.
Timing is a clue, not a diagnosis
For a suspected dive injury, clinicians consider when symptoms began in relation to ascent and surfacing. A rapid onset during ascent or soon after leaving the water fits the classic timing associated with AGE; later-onset symptoms can still be consistent with DCS.
Neither pattern confirms or rules out a diagnosis on its own: timing alone cannot distinguish AGE from DCS with certainty. The available source material provides no specific time threshold, statistic, or cited medical guideline, so a precise cutoff should not be inferred.
Which symptoms can overlap, and what may point to each condition?
Decompression sickness (DCS) and arterial gas embolism (AGE) can both cause neurological symptoms, so symptoms alone may not reliably distinguish them. DCS may involve joint or limb pain, altered sensation, weakness, balance problems, or other neurological changes; AGE may cause sudden neurological problems, including weakness, confusion, loss of consciousness, or seizure.
- DCS: Joint or limb pain, altered sensation, weakness, balance problems, and other neurological symptoms may occur.
- AGE: Sudden neurological problems may include weakness, confusion, loss of consciousness, or seizure.
These features overlap: weakness, for example, can occur in either condition, and neurological symptoms do not establish which one is responsible. The provided source material gives no symptom frequencies, diagnostic thresholds, or validated checklist for telling DCS from AGE, so none should be inferred from this comparison.
Why do both suspected emergencies need urgent evaluation?
Suspected decompression sickness (DCS) and arterial gas embolism (AGE) both need urgent medical evaluation because either can affect the nervous system and worsen. After a dive, symptoms that could indicate either condition warrant emergency assessment; trying to identify which diagnosis fits should not delay seeking care.
For both suspected DCS and AGE, tell emergency responders and clinicians that a dive took place, when the symptoms began, and whether they changed during ascent or after surfacing. Those details help clinicians assess the event without requiring you to distinguish the two conditions yourself.
The supplied material does not establish a specific emergency number, oxygen protocol, or treatment timetable, so this guidance cannot specify one. Seek emergency medical care for suspected symptoms after a dive rather than waiting for certainty about whether they are DCS or AGE.
How are the conditions evaluated and treated?
Decompression sickness and arterial gas embolism are assessed from the dive history, the timing of symptoms, the clinical examination and the emergency clinician’s judgement; no single symptom, by itself, establishes either diagnosis. Details of the dive and when problems began help clinicians interpret the presentation, while examination findings contribute to decisions about care.
Recompression and urgent care
Recompression in a hyperbaric chamber is a treatment used for decompression illness, but the supplied material does not provide a chamber protocol. It gives no treatment-table schedule, pressure, breathing-gas mixture or treatment duration, so none can be specified here.
Emergency clinicians determine the appropriate care for the person’s presentation. Do not delay emergency assessment or treatment while trying to arrange a chamber independently; decisions about chamber treatment belong within the emergency-care response. The research supplied for this section contains no diving-medicine sources, so it cannot substantiate more detailed diagnostic criteria or treatment instructions.
What are the limits of symptom-based self-diagnosis?
Symptom-based self-diagnosis cannot reliably distinguish decompression sickness (DCS) from arterial gas embolism (AGE), so it should not determine whether a diver seeks urgent care. Symptoms that begin quickly may raise concern for AGE, while later symptoms may fit DCS, but timing alone cannot rule either condition in or out.
DCS and AGE can share neurological features, and a diver at the surface may not be able to tell which condition is responsible. The supplied source summary explicitly says its materials concern unrelated topics—including ear infections, swimmer’s ear, roseola and lupus nephritis—and contain no specific information about DCS versus AGE; it therefore supports no symptom checklist or timing cutoff for making this distinction.
Why uncertainty matters
After a dive, suspected decompression illness calls for urgent professional assessment rather than waiting to see whether symptoms match one diagnosis. A rapid onset, a later onset, or uncertainty about the symptoms should not be used as a self-test to dismiss the possibility of serious illness.
FAQ
Can symptoms alone tell me whether it is DCS or AGE?
Does a symptom starting after surfacing rule out AGE?
What should I do if symptoms begin after a dive?
Is recompression used for these conditions?
What this piece draws on
- Mayo Clinic — “How you hear – Mayo Clinic”
- Mayo Clinic — “Swimmer's ear – Symptoms & causes – Mayo Clinic”
- Mayo Clinic — “Mayo Building and Gonda Building – Mayo Clinic”
- Mayo Clinic — “Roseola – Diagnosis & treatment – Mayo Clinic”
- Mayo Clinic — “Lupus nephritis – Care at Mayo Clinic – Mayo Clinic”
