Scuba Diving

What are the bends in scuba diving?

The bends – more properly known as decompression sickness – are something you need to be very aware of when scuba diving.

If you dive deep, if you dive for a long time or you come back up too fast, well…

That’s when decompression sickness can be a serious danger. In fact, in extreme cases, it can kill you.

But don’t worry:

In this article, you will learn all about decompression sickness, the symptoms of the bends and how to avoid them.

What is decompression sickness?

Decompression sickness (DCS) or “the bends” is also called Caisson disease.

It is caused when bubbles of gas (most commonly nitrogen) form in the body tissues due to changes of pressure which occur during scuba dives (or aerospace or high altitude events when the participants experience quick changes of pressure from sea level).

These bubbles can have a range of negative effects on almost any part of your body.

Why is decompression sickness called the bends?

When DCS was first discovered and written down in medical journals, the term “the bends” related specifically to the joint pain which is perhaps the most common symptom.

The other symptoms had similar colloquial names – such as “the chokes” and “the staggers” – as we’ll see below.

What causes the bends?

When you dive beneath the water, you experience greater pressure than you do when at sea level.

As you dive, the pressure may cause the gases in your air tank to dissolve into your body tissues. This is sometimes called “on-gassing.”

Then, as you come back to the surface, the pressure is reduced and the gases should slowly leave the tissue. This is often called “off-gassing.”

However, if the ascent is too fast, the gas will not leave your body’s tissues safely. Instead, tiny bubbles of it will be formed and remain. This is what causes the bends.

Picture it like a bottle of soda. In the closed, pressurised bottle, all is well. You only see all of the carbon dioxide bubbles fizz out of the drink when you take the top off and release the pressure.

Although any kind of gas in a diver’s tank can be affected in this way, nitrogen is the problematic one. This is because your body has no use for nitrogen. All it does is build up in the tissues, prevent blood from flowing properly and stretch or damage the nerves.

The released gas can also cause an embolism, cause blood to coagulate or vasoactive compounds (these are natural agents in your body which decrease or increase blood pressure or heart rate) to be released.

The risk of DCS is increased by:

  • The depth of the dive
  • The duration of the dive
  • The rate of ascent

Decompression sickness – symptoms

The symptoms of decompression sickness are usually found to affect the musculoskeletal and nervous systems.

They almost always develop within 48 hours of the dive (or another event) taking place. However, it is more common for them to develop within 6 hours or even within the first hour.

Some of the most common symptoms of the bends include:

  • Joint pain – especially around major joints like the shoulders and elbows. The original name for this symptom alone was “the bends”.
  • Weak or numb upper extremities – the fingers and forearms.
  • Chest or abdominal pain – when the gas affects the torso. If this is worse when the affected diver is breathing in or it develops into coughing, breathing difficulties, blue lips or blue skin this is the most dangerous form of the condition and needs to be addressed immediately. This also went by the catchy name of “the chokes”.
  • Lower back pain – divers suffering from DCS often find their spinal cord is affected.
  • Weak, numb or even paralyzed lower body – this is again due to the dissolved gas affecting the lower back.
  • Incontinence – if the gas affects the sphincter or urine valve.
  • Fatigue – far more than any given activity should cause.
  • Swollen glands – when the lymph nodes are affected by the gas.
  • Confusion, decreased awareness or restricted or lost vision – these occur when the gases affect the brain.
  • Difficulty walking or with balance – sometimes called “the staggers”, especially when paired with ear ringing, deafness or vomiting caused by the above symptoms.


A note on skin rashes

Skin rashes which are very itchy or which appear red or marbled in colour are often cited as being a symptom of the bends. They are sometimes colloquially known as “the creeps”.

However, these tend to be more related to pressure changes experienced by portions of the skin which were not properly covered by the wet suit.

They may also appear when someone is in the hyperbaric chamber. Again, this is because of pressure changes.

Decompression sickness – treatment

If you or anyone you dive with experiences any of the possible symptoms of the bends you should seek treatment for decompression sickness immediately.

It is important to tell the doctor or staff at the emergency care facility you visit that you have been diving in the past 48 hours so that they know that DCS is a likely cause of your condition.

1) Professional treatment for the Bends

A hyperbaric re-compression chamber is the device required for treatment of DCS:

  • Hyperbaric treatment can take as long as 12 hours or more depending on the severity of symptoms.
  • The chamber is a pressurized environment which reduces the size of the bubbles and helps them to be reabsorbed.
  • It also provides large amounts of oxygen to the damaged tissues.

Before treatment in the re-compression chamber, a doctor will usually test the person suffering from the condition and hook them up to IV and oxygen lines.

Afterwards, hospital admission for monitoring of their status is a likely outcome.

2) Emergency care for DCS

Calling the local emergency services should always be your first port of call when a case of the bends is reported.

Be sure that the professional you are speaking to understand:

  • The diver has decompression sickness.
  • They need to be transported lying flat on their back.
  • If they are going to be airlifted, the vehicle should travel below 1000 feet if at all possible – or be pressurized to sea level.
  • A hyperbaric chamber will almost certainly be required for their treatment, so in the hospital, they will be taken to needs to have one. You can search online for where the closest chamber to you is on the Divers Alert Network website.

If you absolutely cannot reach a hospital in time, there are a few things you can do to keep a person suffering from the bends stable until help arrives:

  • 1. If they experience a drop in body temperature, keep them warm with blankets.
  • 2. If you have an oxygen mask, put it on them.

Don’t dive until you’ve dived with the experts

Avoiding getting the bends is relatively simple:

Don’t go scuba diving without getting some proper instruction and supervision first. There are several organizations which will certify that you know how to dive safely.

You want to be on the lookout for NAUI (National Association of Underwater Instructors) or PADI (Professional Association of Diving Instructors) courses to make sure you are getting qualifications which are recognized internationally.

At the Ko’ox dive shop here in Playa Del Carmen, we instruct fresh-faced new divers in how to scuba dive in safety each and every week with our PADI courses.

Get in touch with us before you take the plunge and we’ll show you how to dive safely – with no risk of getting the bends.