Administer oxygen immediately when decompression illness occurs to improve outcomes.

What action should be taken immediately if decompression illness occurs?

• A. Ascend to the surface
• B. Administer oxygen immediately
• C. Swim to the nearest boat
• D. Ignore symptoms if feeling fine

Answer: (B)

Administering oxygen immediately is the appropriate action when decompression illness occurs. This condition, also known as "the bends," results from nitrogen bubbles forming in the bloodstream or tissues as a diver ascends too quickly. Administering oxygen helps to reduce the size of these bubbles, assists in the elimination of nitrogen from the body, and provides critical support to the body's healing processes. Oxygen therapy can decrease symptoms of decompression sickness and improve outcomes. It is vital for the diver to receive high-flow oxygen as soon as possible, ideally while other emergency procedures are initiated, such as arranging for transport to a hyperbaric chamber for further treatment. Prompt action can significantly influence recovery and mitigate potential long-term damage. While the other actions listed might seem plausible, they could exacerbate the situation. For example, ascending to the surface can worsen the condition due to changes in pressure and further bubble formation. Swimming to the nearest boat may delay necessary treatment and risk additional complications. Ignoring symptoms, even if feeling fine at the moment, can lead to a worsening of the condition and delayed response to a serious health emergency.

What to do the moment decompression illness shows up — fast, clear, and effective

Decompression illness, sometimes called the bends, isn’t haunted by mystery. It’s a real risk when ascent is rushed and nitrogen bubbles decide to take up residence in your blood and tissues. You’ve trained for calm, controlled ascents, but if symptoms pop up, you need a plan that’s simple to execute and incredibly lifesaving. The first action is a single, powerful move: administer oxygen immediately.

Let me explain why that single step matters so much. When a diver rises too quickly, nitrogen doesn’t have time to exit the body safely. It forms bubbles that can interfere with how your tissues and organs function. Oxygen plays a dual role here. First, it helps by reducing the size of those bubbles and nudging nitrogen out of your system faster. Second, it supports your body’s healing processes as it fights off inflammation and tissue stress. In many cases, oxygen won’t fix everything, but it buys precious time and limits damage while you arrange medical care. So, if you’re ever in a situation where decompression illness could be showing up, the oxygen you carry isn’t just a convenience—it’s the first line of defense.

Here’s the thing about the other options you might be tempted to chase in the moment. Ascending to the surface? That can make bubbles grow or relocate, which worsens the problem rather than helping it. Swimming to the nearest boat could delay critical treatment and put you at risk of fatigue or a misstep. Ignoring symptoms because you feel fine now? That’s a trap—symptoms can evolve, sometimes hours after the event. The best course is focused, immediate oxygen with professional help on the way.

What happens in the body during decompression illness? A quick mental picture helps you stay calm when symptoms show up. The nitrogen that’s dissolved in your blood and tissues under pressure can form bubbles as pressure decreases during ascent. Those bubbles can disturb blood flow, irritate nerves, and inflame joints and muscles. Symptoms aren’t always dramatic. They can start as joint or muscle pain, dizziness, numbness or tingling, fatigue, skin itching or mottling, chest pain, or shortness of breath. If anything feels off after a ascent, treat it as a priority medical situation and act quickly.

The one move you should lock in right away is high-flow oxygen. Here’s a practical way to do it, without turning the scene into a DIY medical clinic:

Immediate actions to take if you suspect decompression illness

• Stop ascending. If you’re still in the water, pause and stay as still and calm as possible. Don’t exert yourself.

• Get the oxygen flowing. Use high-flow 100% oxygen as soon as you can. If you’re on a boat and have a mask and regulator that can deliver 100% oxygen, attach it and deliver a steady, deep breath. If you’re trained and equipped with a non-rebreather mask, fit it snugly and push for the highest flow you can sustain.

• Call for help. Alert your buddy, boat crew, or dive operator. Then contact emergency services and tell them you suspect decompression illness and need rapid transport to a hyperbaric chamber.

• Keep the diver comfortable but still. Have them lie down if possible, keep them warm, and prevent shivering, which can increase stress on the body. Do not give food or drink unless they’re fully alert and safe to swallow.

• Monitor vitals and symptoms. Check for changes in breathing, consciousness, or new symptoms as time passes. If there’s a change, report it to responders immediately.

Why oxygen first? Because it’s the fastest way to support the body at a moment when every minute counts. It’s not a substitute for medical treatment; it’s a doorway to better outcomes while you arrange professional care. The goal is to minimize harm and keep the diver stable until they can reach a hyperbaric chamber, where specialized treatment can apply pressure and further promote bubble resolution.

Getting to a hyperbaric chamber isn’t the end of the story; it’s the beginning of targeted healing. Modern treatment typically involves controlled pressure to shrink the nitrogen bubbles and help them dissolve back into the body safely. The sooner a diver receives this therapy after symptoms begin, the better the chances of a full recovery. That’s why your best plan on the surface is to administer oxygen promptly and get medical help en route.

A quick note on prevention while we’re at it. You already know great training teaches you to ascend gradually, respect safety stops, and monitor your dive computer or tables. Here are some reminders that help keep DCI from becoming a problem in the first place:

• Ascend slowly. A common rule is to limit ascent rate to no more than a slow, steady climb. Your dive computer or tables will guide your actual numbers.

• Plan safety stops. A short stop at around 15 feet for several minutes gives your body time to off-gas nitrogen before you break the surface.

• Stay within your limits. Don’t push into depths or durations that exceed your current certification level or experience.

• Hydration and rest matter. Well-hydrated tissues cope better with pressure changes; fatigue can cloud judgment and reaction times.

A few practical reminders can go a long way. Keep a reliable supply of 100% oxygen on board or on your person if you’re a frequent diver, and make sure everyone on the boat knows where it is and how to use it. Practice your emergency procedures with your buddy so you can act calmly and decisively if the moment arrives. It’s not about fear; it’s about preparedness and care for your own health and the health of your dive buddy.

A tangent worth considering: how do you recognize a true emergency from a passing discomfort? Decompression illness isn’t a single, dramatic event that looks identical in every person. Sometimes the signs are mild or delayed. If you’ve recently ascended and you notice joint pain that won’t quit, a strange fatigue, numbness, trouble breathing, or confusion, treat it as serious and seek help right away. It’s better to be cautious.

If you’re curious about how all the pieces fit in a real-world scenario, here’s a quick vignette. A diver surfaces after a long, thermally demanding dive. They start feeling tightness in the chest, a dull headache, and a ring of sensation across the shoulders. They stop, signal for assistance, and switch to high-flow oxygen. A quick call to rescue services is placed, and a boat team coordinates transport to a hyperbaric chamber. In the hours that follow, medical staff monitor vitals, administer additional oxygen as needed, and guide a careful reintroduction to pressure therapy. It’s not glamorous, but it’s a blueprint for safety—and it works because the first move is clear and immediate.

If you’re teaching someone else how to respond, you’ll want to stress a few core ideas. Oxygen is the frontline defense; don’t wait for symptoms to pass on their own, and don’t ignore the urge to seek help. The faster you begin oxygen therapy and arrange professional care, the better the odds of a quick, full recovery. It’s a practical blend of training and human intuition—knowing when to act and how to coordinate help without delay.

Let’s wrap this up with a down-to-earth takeaway: decompression illness is real, and it’s preventable with good habits and quick, correct action if symptoms appear. The priority is oxygen, followed by rapid transport to a hyperbaric facility. The rest is support—keeping calm, staying warm, avoiding further exertion, and letting professionals take the lead after you’ve laid down the first, essential foundation of care.

So next time you’re preparing for a surface interval or reviewing your on-board safety plan, picture that moment you recognize a potential DCI sign. You’ve already got the tool in your hand—the oxygen reservoir—and you know the first move is to use it now. The ocean is generous, but it’s also powerful. Your best safety practice is to pair respect for the water with quick, decisive action when something signals trouble. That combination is what keeps you in the game, enjoying the wonder of open water while staying as safe as humanly possible.