You already know some of the dangers of scuba diving: drowning, boating accidents, dangerous encounters with marine life, and so on. However, there’s danger that is silent but no less dangerous than the rest. It is known as “the bends” or decompression sickness (DCS). You’ll know you are experiencing the bends when you have symptoms like fatigue, pain, and immobile, bent joints. In some cases decompression sickness can result in death.
As you can imagine, decompression sickness is a serious issue. It can happen to you when you surface too quickly. As you do, the rapid change in pressure from high to low pressure sets of a chain reaction in your body that will wreak havoc on your joints and internal organs. You may feel these effects as quickly as 15 minutes after surfacing, or even up to 12 hours later.
Before you go scuba diving, you should learn more about the dangers of decompression sickness – its symptoms, causes, and treatment – and why you should always surface slowly so that you can avoid it.
Decompression Sickness Happens At the Worst Possible Time
As we mentioned, decompression strikes when you’re most vulnerable – when you are trying to get to the surface. You may have very legitimate reasons for wanting to get out of the water. Perhaps you are having a medical episode, or there was an equipment malfunction, or you’re running out of air. Maybe you just made a small mistake and ascended a little too quickly. Unfortunately, the ocean doesn’t care. Or more specifically, the nitrogen in your body doesn’t care.
What Happens When You Ascend Too Quickly?
To explain this next point, first you have to understand that normal air is composed of 21% oxygen and 79% nitrogen. This is how much nitrogen your body is used to absorbing. However at deep depths, due to the extreme pressure acting on your body and the air, your body’s tissues absorb nitrogen in higher amounts. That in itself is not the danger.
The problem arises (literally) when you begin to ascend, and the water pressure around you decreases. As it does, the excess nitrogen absorbed in your body starts to get released. If you surface too quickly, the dissolved nitrogen will form bubbles in large quantities. You can effectively “fizz up”, and it is these bubbles that can cause mild to deadly symptoms.
The severity of your symptoms depend on how many bubbles form and where the bubbles travel to. These bubbles tend to accumulate around the joints, reducing your mobility and causing your joints to stay bent (hence why it is called “the bends”). However, the bubbles can also block off your blood flow which can have some life-threatening consequences.
The Deeper You Dive, the Greater the Risk of Decompression Sickness
Every 10m (33ft) underwater you dive, the atmospheric pressure increases by 14.6 pounds per square inch. This means that every square inch of your body feels 14.6 pounds of force acting on it. The significance of this number is that it is what’s referred to as one atmosphere of pressure, which is the weight of the earth’s atmosphere at sea level (source). So on land at sea level, you are experiencing one atmosphere of pressure. At 10m underwater, you feel two atmospheres of pressure, and so on.
As you can imagine, you don’t have to dive very far to have multiple atmospheres of pressure acting on you. The further you dive, the greater the pressure and therefore the more nitrogen gas is being dissolved into your tissues. This is known as “on-gassing.” Since you have far more nitrogen in your tissues, you have a higher chance for nitrogen to form bubbles in the wrong places.
When you ascend, the water pressure decreases and nitrogen starts to leave the tissues. This is known as “off-gassing.” The point is to ascend slowly so that the nitrogen can leave safely without forming too many bubbles. As long as you ascend slowly, and stop for the requisite amount of time as recommended by a dive computer or a dive table, then you should be able to avoid getting bent.
Can Decompression Sickness Be Fatal?
Absolutely. Decompression sickness is not a laughing matter. Even if you don’t die, you may have serious side effects like paralysis or brain damage. You should be doing everything in your power not to get bent.
With that said, even when decompression sickness is not fatal, it can produce a variety of symptoms. The severity depends on the maximum depth the diver reached and how fast the ascent was. It also affects people based on their age, gender, level of fitness, and overall health. The levels of DCS can be categorized into two types: low and high severity.
Type I DCS (Low Severity)
The less severe symptoms of the bends is general pain. You may experience pain and restricted mobility in the joints of the legs, arms, or back. Sometimes it is unclear where the source of the pain is coming from.
The pain may start off mild, but can increase over time. It may even become so severe that the victim buckles over and cannot stand on their own. People who have gotten bent describe the feeling as a stabbing pain that feels like someone is drilling holes into your bones.
Some additional symptoms of the Type I DCS are: decreased appetite, skin rashes, skin molting, itching, swollen lymph nodes, nausea, and extreme fatigue. These symptoms are not life-threatening, but they may be a precursor to even worse Type II symptoms. Whether you are experiencing type I or type II symptoms, you should seek medical attention immediately.
Type II DCS (High Severity)
In severe cases, divers may experience type II decompression sickness. At this point, the negative effects may be permanent and divers can get paralyzed or die from it.
Type II symptoms may follow after type I symptoms, so just because someone appears to be fine does not mean that their condition won’t worsen. The long-term effects of decompression sickness can be severe, so do not hesitate to go to the hospital.
How DCS Affects the Spinal Cord
The spinal cord is particularly affected by the bends. Sometimes the nitrogen bubbles will enter the spinal column, and this can have a permanent, damaging effect. When this happens, divers may experience numbness, weakness, and a tingling sensation like pins and needles are attacking their spine.
They may also feel a combination of these sensations in their arms and legs. The first wave of weakness and pain can cause irreversible paralysis. It may take hours for this to happen, so get medical attention before it worsens.
Additional symptoms of spinal cord DCS include the inability to urinate. On the other extreme, it can cause the victim to become incontinent and to urinate and defecate uncontrollably. Back and abdomen pain is also common.
How DCS Affects the Brain
When symptoms of type II DCS affect the brain, that means the nitrogen bubbles have formed in the brain, or they made their way to the brain by traveling through the veins. Common symptoms include: headaches, hallucinations, confusion, slurred speech, and loss of consciousness.
If the nitrogen bubble restricts blood flow to the brain or damages the brain tissue, then it can result in violent seizures, severe neurological trauma, and the affected individual may even slip into a coma.
How DCS Affects the Inner Ear
When nitrogen bubbles form or travel to the inner ear, it can cause: vertigo, ringing in the ear (tinnitus), and temporary hearing loss. You may feel nauseous, dizzy, and find it hard to walk in a straight line. The ringing in the ears can get so severe that that might be all you hear for a time. Even after getting treated for DCS, the dizziness and ringing may linger for a time.
How DCS Affects the Lungs
When nitrogen bubbles form in the lungs, it can cause adverse reactions in mere moments. The minor symptoms are shortness of breath, exhaustion, confusion, pain, and a cough. As it progresses, the symptoms become nightmarish. Rather than cough up the typical mucus or clear stuff, you can start coughing up foamy, frothy blood. If this happens, it’s a sign that decompression sickness has ruptured your lungs.
How to Prevent Rapid Ascents and Avoid DCS
Nowadays, it has become almost mandatory to dive with a dive computer. In fact, you should probably be diving with two. Rather than having to look at complicated dive tables like in days past, a dive computer can monitor your depth and changes in pressure during your ascent. It will perform calculations and recommend a safe ascent rate, if any decompression stops are needed, and how long you should stop for. If you ignore or miss any of its recommendations, the dive computer will alert you with its alarms.
You really should be diving with a dive computer nowadays. If you’re not sure which ones are good, we have written reviews on which dive computers are the best for beginners, and which ones are the most affordable.
Pro-Tip: Treat each dive as a decompression dive.
The minute that you are underwater, your body is subjected to greater pressures compared to the surface. This means that at any depth, your body has absorbed more nitrogen than usual, which means nitrogen bubbles can form when you ascend. This extra nitrogen needs time to slowly escape, unless you want to get bent.
The reason why we are stressing to treat each dive as a decompression dive is because there is this concept of no-decompression dives. It refers to dives where no decompression stops are required because you have stayed within your no-decompression limit. Just because you don’t have to perform a deco stop does not mean you are free to ascend as quickly as you like. The concept of a no-decompression dive can give divers a false sense of security, so we recommend to treat each dive like a decompression dive.
Can You Die From Getting Bent?
With a chance of causing permanent damage to your spine, brain and lungs, it is no surprise that decompression sickness can be fatal. You may also suffer from seizures, numb limbs, or loss of consciousness leading to a coma. Even if you are only experiencing mild symptoms, it may be a sign of something worse coming.
If left untreated, the type I symptoms can progress to type II symptoms. Then you can start to experience such effects as arterial damage or blockages so severe your heart can’t function and neurological damage so damaging that your brain shuts down. So if you or a buddy starts to experience the symptoms of DCS, you should take it seriously.
First things first, call emergency medical services. Also contact the Divers Alert Network (DAN) to speak to a professional who can give you advice on what to do in the meantime, as well as inform you of the nearest hyperbaric chamber (decompression chamber).
Next, if there is an oxygen mask available, provide it to the affected individual. Fresh oxygen must be continuously administered from now throughout the rest of their treatment. When being transported to the hospital, it is not recommended to travel by air. High altitudes can cause decompression sickness to worsen.
Additionally, cover them up with a blanket to keep their body temperature warm. Keep a close eye on them to ensure that they don’t suddenly lose consciousness. They need to quickly get into a hyperbaric chamber, which has proven to be an effective treatment for the bends.
In a hyperbaric chamber, the diver is re-pressurized to a depth that is at least equivalent to or even deeper than their last dive. This is to stop rapid release of stored nitrogen in the body. The chamber then slowly de-pressurizes until the diver returns to atmospheric pressure. This effectively mimics the decompression stops that a diver should do as recommended by their dive computer.
Death occurs typically in the most extreme scenarios where treatment was delayed or a reckless rapid ascent was done from a deep depth.