What are the Bends in Scuba Diving and How can you Prevent them?

Scuba diving is a hobby and sport that is continuing to increase in popularity every year. When learning to scuba dive, multiple factors need to be taken into consideration – finding the appropriate diving equipment, searching for the perfect location, learning the right diving qualifications, etc. All of these factors are essential. For scuba divers, the risk of decompression sickness plays an important role; therefore, it’s always best practice to gain complete knowledge about this activity before indulging in it.

Table of Contents

Decompression sickness (DCS), also known as the bends, diver’s disease, caisson disease, and aerobullosis. It is a condition that arises during depressurization from dissolved gases that come out of the solutions present in your body in the form of bubbles.

While underwater diving decompression is the main cause of this disease, other depressurization events such as extracurricular projects from spacecraft, flying in unpressurized aircraft at high altitude, and emerging from caisson can also cause you to experience DCS. Here is all you need to know about the bends in scuba diving:

What Are the Bends?

As mentioned above, the bends occur in scuba divers, high-altitude flyers, and during aerospace events, when dissolved gases (mostly nitrogen) come out of solution in bubbles. This disease can affect any body part including the skin, heart, brain, lungs, and joints.

Scuba divers, astronauts, and aviators experience rapid changes in pressure during scuba diving and from sea level respectively. Commercial divers breathe a special mixture of helium and oxygen known as heliox. In all these situations, bubbles of gas are formed inside the body and cause the bends. We’ll focus on the bends in scuba diving in this article, as it is known as the most common activity resulting in the mentioned disease.

How Do You Get the Bends?

As a scuba diver descends into the water, the pressure of nitrogen or any gas from their air tank increases. The nitrogen causes the pressure to go up an additional 11. 6 pounds per square inch for every 33 feet of depth in ocean water.

Unlike the oxygen present in the diver’s tank that gets utilized by them while swimming underwater, the body doesn’t make use of the nitrogen gas; therefore, with the increase in pressure due to nitrogen, more of this gas gets dissolved and builds-up over time into the diver’s body tissues. The longer they remain at depth, the greater the amount of nitrogen that gets dissolved.

A diver’s blood flow gets blocked, and their nerves and blood vessels are disrupted when they return to sea level and nitrogen bubbles are released. This causes stretching and tearing of the blood vessels and nerves. Some of the other problems caused by this are emboli, blood coagulation, and the release of vasoactive compounds.

To understand the bubble formation process further, a can of carbonated soda can be used as an example. The soda can is filled with carbon dioxide gas which is not visible; it is completely dissolved under pressure until the can is opened.

As soon as you open the can, the pressure gets released which causes the gas to escape from the solution in the form of bubbles. Similarly, a diver’s return to the surface is quite similar to the opening of the can of soda.

As a scuba diver swims to the surface of the water, there is a significant decrease in pressure. The nitrogen that has already dissolved in the diver’s tissue seeks to leave again, as the human body is only capable of holding a certain amount of gas, depending on that nitrogen pressure.

How Do You Prevent the Bends?

You can take some preventive measures for the bends or decompression sickness by carefully listening to and understanding the guidelines taught during professional diving courses and strictly implementing those guidelines while diving. You should also be aware of the actions that play a huge role in increasing the risk of developing the bends. Following are some important factors to consider to minimize the risk of developing the bends.

Table Recommendations

Never dive outside dive table recommendations. Proven to be a great resource for scuba divers, dive tables are charts that usually come in booklets or printed on cards that help divers in determining various aspects of specific dives, relating to breathing gas, and when to take decompression stops during those dives.

Due to the rapid advancements made in technology, we now have the dive computer, also known as a personal decompression computer or decompression meter. This is a great device that can be used in place of those tables. It is used by an underwater diver to measure the depth and time of a dive so that a safe ascent profile can be calculated and displayed to help the diver avoid DCS.

Flying Recommendations

It is recommended to fly 12 hours after your last dive, given that you dove within the dive tables and didn’t require any decompression stop

If you were involved in complicated diving, it is recommended to wait for 48 hours before you fly

In general, the longer you wait to fly after scuba diving, the less your chances of developing the bends will be. However, even long waits do not ensure 100% immunity to the disease

Divers Alert Network (DAN) collected some data from 1987 to 1999, showing that 17% of scuba divers in their injury database experienced their first symptoms of decompression sickness either after or during flying.

Cold Temperatures

Temperature also plays a vital role here. Diving in cold water is highly discouraged. The volume of the gas shrinks when exposed to low temperatures; this increases the chance of the bends developing.

Obesity

Obesity can affect lipid metabolism. Obese individuals have a higher chance of developing the bends as nitrogen is lipid-soluble

Dehydration

According to a study on the effects of dehydration on the risk of severe DCS, it was concluded that dehydration significantly increases the overall risk of severe bends disease.

Vigorous Exertion

The blood flow of the body increases and so does its ability to carry gas when you expose it to intense exercise and exertion during diving. When you go in extreme depths during a dive, remember to keep exertion to a minimum.

How Do You Recover From the Bends?

Take the following steps to recover from the bends:

Self-Care

• Rescue the diver from the waters and provide them with urgent care within the restrictions of your training.
• If you see that they have developed hypothermia i.e. their body temperature has dropped, then dry them and cover them with warm blankets.
• If an oxygen mask is available, apply it to the diver immediately.
• Now, take the individual to an emergency care facility in a supine position. They should be lying horizontally on their back.
• While using air transport, try to find one that can move the diver below a thousand feet.
• During transport, use high-flow oxygen in case of availability.

Seeking Medical Attention

If you notice any symptoms or signs of the bends within 48 hours of diving, you should seek immediate medical attention. Along with informing your doctor of your symptoms, also mention your recent diving activities in details for them to get a better understating of your condition.

Medical Treatments for the Bends

• If the diver goes into shock or through severe breathing problems, their medical practitioner will first treat those life threats.
• Next, they will require IV fluids and high-flow oxygen. Urine and blood tests will be conducted in order to assess their hydrations status and to detect any blood clots.
• The diver will then be most likely sent to a hyperbaric chamber for recompression. The chamber is pressurized using oxygen and air based on preset protocols.
• Pressure depths of thirty to sixty feet are stimulated. This process might take a total of 12 hours or more.
• At these preset chamber pressures or depth, the bubbles are minimized in size or simply reabsorbed to provide sufficient blood flow.
• The injured tissues receive high quantities of oxygen through the recompressions and further formation of bubbles is prevented.
• Hospital admission may be in order for monitoring the medical condition of the diver and making sure that the symptoms do not recur.

What Risk Factors Increase the Chances of Decompression Sickness

Following are some risk factors that increase the chances of decompression sickness:

Physical and Medical Health

Poor physical health and medical fitness can increase the risk of the bends for a diver. Regular strength training and aerobics are recommended to maintain or improve physical fitness.

Post-Dive Air Travel

As the atmospheric pressure on the ground is higher than the pressure in an aircraft cabin, flying after scuba diving can increase decompression stress and also the risks of a diver developing the bends.

Intense Exercise

Extreme exertion right after a dive increases your blood flow along with the capacity of your blood to carry gas. Therefore it is best to avoid any intense exercises right after your dive.

Thermal Exertion

Moderation is the key here. It is best practice to avoid long exposures to cold water without wearing protective suits that come with active heating. Taking hot baths right after cold-water dives can also provoke DCS.

Can You Die From the Bends?

A scuba diver can, in fact, die from the bends. There are various symptoms of the bends which mostly include pain in the joints, arms, and legs. If one suffers from more severe symptoms such as difficulty in speaking or walking and dizziness, they can be signs of serious cases of the bends and can lead to a coma or death.

What Other Decompression Syndromes Exist?

Type 1 DCS

Although not life-threatening, type 1 DCS can be a warning for type 2 DCS development.

Cutaneous Decompression Sickness

Bubbles form in skin capillaries and result in a rash, often near the shoulders and the chest.

Joint and Limb Pain Decompression Sickness

Joints ache and/or pain. The pain either remains in one place or moves around the joint.

Type 2 DCS

These syndromes can be life-threatening and usually affect the nervous system.

Neurological Decompression Sickness

Bubbles affect the nervous system and symptoms include respiratory problems, numbness, unconsciousness, and tingling. This decompression syndrome can lead to paralysis or even death if left untreated.

Pulmonary Decompression Sickness

Bubbles form in lung capillaries. This syndrome can interrupt blood flow to the lungs and cause life-threatening heart and respiratory problems.

Cerebral Decompression Sickness

The bubbles find their way into the arterial bloodstream, transfer to the brain, and lead to an arterial gas embolism. The symptoms include headaches, unconsciousness, confusion, and blurred vision.

Can you get decompression sickness (Bends) while freediving? 

Alexander Nilsson • Jul 27, 2020

An article about why and how decompression sickness (DCS) manifests, and how to reduce the risk of getting it in the first place.

You have probably heard about scuba divers getting “divers disease” or decompression sickness, also called “bends”.
In scuba diving you learn that you shouldn’t swim up faster than the bubbles you exhale. And you should also do a decompression stop before you reach the surface.

In freediving and spearfishing however, you rarely hear about it. But the truth is that it happens more than you think.

What is decompression sickness? This is what happens in the body when you get decompression sickness

So what happens is that, nitrogen bubbles build up in the body and are not properly dissolved before resurfacing.
The nitrogen bubbles in your system might then get stuck and block tiny blood vessels. This can lead to heart attacks, strokes, ruptured blood vessels in the lungs and joint pain.

Here below is a link to a story of one of my freediving friend who recently got decemopression sickness while in a competition in Indonesia.

https://www.dansa.org/blog/2020/03/27/getting-decompression-sickness-while-freediving#:~:text=Unlike%20when%20breathing%20compressed%20gas,dives%20over%20a%20short%20time.

What can cause decompression sickness?

1. Not enough surface interval
2. Too long time at depth
3. Multiple deep dives (+55m)

What makes you more susceptible to decompression sickness?

1. Dehydration
2. Lack of sleep
3. Being overheated
4. Genetically factors
5. Muscle fatigue

So, how do we avoid getting decompression in the first place?

Have sufficient time on the surface in-between dives

Most importantly, we want to make sure that we’re taking sufficient enough surface interval in between dives. Meaning, when we’re diving to less than 30 meters, we want to rest at the surface for at least three times your dive time.

So, let’s say that your dive to 30 meters took 2 minutes, then you need to wait for at least 6 minutes before you dive again. If you would be diving between 30 and 50 meters, then you need to multiply your dive time with *4.
Don’t dive more than one time a day deeper than 50 meters.

Drink enough water



Be sure that you are well hydrated when spending time in the water, especially when in a warm climate.
Bring a water bottle to the buoy and drink some while on the surface.

Sleep at least 7 hours the night before freediving

We have seen that there is an increased risk of getting decompression sickness when tired and exhausted, so make sure to have a good nights sleep before going out diving.

So, what are the symptoms of decompression illness?

• Localized deep pain, ranging from mild to excruciating. Sometimes a dull ache, but rarely a sharp pain.
• Active and passive motion of the joint aggravates the pain.
• The pain may be reduced by bending the joint to find a more comfortable position.

• Itching, usually around the ears, face, neck, arms, and upper torso
• Sensation of tiny insects crawling over the skin
• Mottled or marbled skin usually around the shoulders, upper chest and abdomen, with itching
• Swelling of the skin, accompanied by tiny scar-like skin depressions

• Altered sensation, tingling or numbness, increased sensitivity.
• Confusion or memory loss
• Visual abnormalities
• Unexplained mood or behaviour changes
• Unconsciousness

• Ascending weakness or paralysis in the legs
• Problem urinating
• Girdling (also referred to as girdle, banding, or tightening feeling) around the abdominal region and/or chest

• Headache
• Unexplained fatigue
• Generalised malaise, poorly localised aches

• Loss of balance
• Dizziness, vertigo, nausea , vomiting
• Hearing loss

• Dry persistent cough
• Burning chest pain under the sternum, aggravated by breathing
• Shortness of breath

Can you get decompression sickness from just shallow snorkeling?

The short answer is Yes, although you would have to do a serious amount of shallow dives with almost no surface interval during many hours to risk that. I have heard stories from some of my spearfishing friends that have gotten the bends from a day trip of spearfishing for 8 hours diving to deph of maximum 20 meters. The reason why they got decompression at that time was probably because they didn’t spend enough time on the surface between the dives.
If you on the other hand would be snorkeling around at the reef of say 5 meters, it would be most unlikely to run the risk of decompression sickness, Just due to the sheer volume of diving one would have to do.

The most important thing you can do to mitigate the risk of getting decompression sickness

If there is one thing that you should remember from this article, then that is to spend sufficient time on the surface in-between dives. Be it if you dive to 10 meters, or to 50 meters. Always spend at least 3 times the dive time on the surface between the dives (if the dive is shallower than 30 meters).

Freediving is one of the safest activity one can do, if practiced according to the safety standards. And part of the safety standards should be to consider the risk of decompression sickness.

I hope that this article have cleared up some questions, and hopefully will let you safely enjoy the underwater world!

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Safety Rules for Apnea (Freediving)

Safety Rules for Apnea (Freediving)

Never dive alone. Choose an experienced partner. For diving into the depths, a cable is pulled along which
followed by a diver. The partner monitors the dive from the surface and keeps track of the time. He
must begin to dive towards the freediver, timing so as to meet
it at a depth of 15 m and emerge, passing in parallel with it the most dangerous section
from 15m to the surface.

If necessary, the partner must be ready quickly
transport the freediver to the surface and provide first aid.

For safety when diving deeper than 30
m requires the presence of a scuba diver at a depth and a system has been worked out
the freediver’s quick ascent to the surface. Depending on the depth of the planned
diving and conditions (visibility, fresh or salt water) may require
more scuba divers occupying positions at intervals of 10-15 m.

Never dive in free mode after diving with
scuba diving.

Increased nitrogen content in tissues after diving with
scuba diving can lead to decompression sickness, because on a new dive and
subsequent rapid ascent to the surface of nitrogen, not having time to stand out through
lungs, takes the form of gas bubbles in the blood and other tissues of the body.

At least 12 hours must elapse after scuba diving
for safe freediving.

Never force pressure equalization.

Do not test your eardrums.

When starting a dive, try to blow every 3 m without
waiting for pain. If pressure cannot be equalized immediately,
stop diving. The thought that the target is close and there are only 2-3 meters left to
bottom or to the card with the intended depth and you can be patient – deceptive.
The result may be a rupture of the eardrum, pain shock, dizziness when
ascent, which can lead to loss of consciousness. And even with a successful ascent
a lot of discomfort and long follow-up treatment – not very attractive
perspective.

When using a nose clip, remove it immediately
after the turn, starting the ascent to the surface.

Choose the right load.

More cargo makes it easier to dive –
“fall” down, but do not forget that then you have to emerge. Congestion will lead to
too much energy consumption during ascent, when the supply of oxygen is running out. Except
in addition, if you dive too fast, you may have problems with alignment
pressure. The load must be selected in such a way that at a depth of 15 m
buoyancy was neutral.

Before training, plan your dives with
partner, taking into account all the conditions of the upcoming diving (weather, waves, currents,
visibility, etc.).

Every freediver should know what he is going to do
partner (number of warm-up dives, dives to the maximum depth, etc. ).

Everyone should know whom he insures (with the number
diving more than 2).

The presence of a current must be taken into account (if the current is more difficult
float vertically along the cable), visibility (in case of poor visibility, additional
security measures), water temperature (for the correct selection of the suit and cargo),
surface conditions – waves (the need for a sufficiently large and stable buoy).

Do not leave the snorkel in your mouth while diving.

The snorkel must be removed from the mouth before diving.
Usually the freediver either holds it in his hand or leaves it to the belayer. Tube in mouth
at depth makes it difficult to equalize the pressure, and a sharp exhalation into the tube for cleaning
from water when returning to the surface can lead to loss of consciousness (blackout),
caused by lack of oxygen.

Never exhale underwater or exhale too sharply.
forced exhalation at the surface immediately after ascent.

Exhalation while moving up leads to a decrease in buoyancy, which
in turn, requires more effort to rise to the surface. Besides,
additional drop in pressure in the lungs as a result of exhalation leads to the fact that
the reserve supply of oxygen from the blood is sent to the lungs instead of the brain, which can
lead to loss of consciousness.

When diving in depth, always use the rope and signs on
surfaces marking the dive site.

The freediver must not move more than 2 meters to the side
away from the line to be in the line of sight of the safety team.

If the cable is not lowered from a ship or boat, then
surface should have a bright (orange or red) buoy indicating the location
diving for passing ships. In addition, the buoy must be large enough
to stay on the surface even if two freedivers are at the same time
are pulled along the cable when ascending. The buoy must be stable enough to
so that the freediver can rest by leaning on it between dives.

The cable must be at least 10 mm thick to
it is convenient to take it by hand if you need to pull yourself up or push off from the cable. For
for better visibility, it is desirable that the cable be white.

If the diving line is lowered from the ship, on the ship
the flag “Divers in the water” is raised.

Always respect the required interval between dives.

The interval between dives to a depth of more than 30 m must not be
less than 4-5 minutes, and up to 8 minutes depending on water temperature and depth. For that
time the balance of gases in the body has time to return to normal.

If you are going to dive to your maximum or close
depth to it – do not do more than 2-3 dives to a maximum in one training
session. After diving to a depth of more than 60 m, the body needs about 48 hours to
full recovery.

Never hyperventilate.

Hyperventilation is called breathing, during which
more than 15 breaths per minute. Hyperventilation lowers the CO2 threshold
to increase the breath holding time. But does not accumulate during hyperventilation
additional O2, and also creates muscle tension and acceleration of the heart
rhythm, which leads to a rapid consumption of oxygen and an increased risk of loss
consciousness.

Proper ventilation before diving is considered
ventilation based on deep breathing of yogis – as slow as possible,
calm breathing, while intensively using the entire volume of the lungs, creating
maximum circulation of O2 and its additional accumulation in tissues. Similar breathing
also promotes concentration and complete relaxation before
immersion. Avoid sharp turns when starting to climb to the surface. When turning towards the surface, it is better to first take
horizontal position, and then turn head up. A sharp turn can lead
to the outflow of blood from the brain and loss of consciousness at depth.

Never look down when diving and never look up when
ascent.

Additional neck curve makes pressure equalization difficult
when immersed. When ascending, tilting the head results in obstruction of the flow
blood circulation in the neck and brain.

This position of the body reduces its hydrodynamics.

In addition, the psychological effect of looking down or up
may become panic.

Do not drastically increase traffic intensity at the last
ascent to the surface.

Ascent movement from the turn to the ascent
the surface must be very calm and measured in order to keep to the end and
make the most economical use of the remaining O2 supply.

Do not dive with a full exhalation.

Full exhalation diving is a training technique
used by very “advanced” freedivers. For similar techniques
must be approached with extreme caution, having a very high level of fitness and
great diving experience, under the guidance of an experienced instructor.

Never continue diving in the event of a samba or blackout.

In case of samba (loss of motor control) or blackout
it is necessary to stop diving for at least a day, depending on the degree
the severity of the incident.

Consider the time required for physiological adaptation
body to the diving process.

Never force new depths or more
long breath holding time. Our bodies have great potential for
adaptation to new extreme conditions, but this takes time.

Forcing new depths and breath holding times can
cause serious

physical injury and damage and/or
psychological barrier.

Maintain the right mental attitude.

Avoid negative thoughts before and during diving.
Correct positive

mental attitude in freediving – more than half
the success of the entire enterprise.

Mind control training is not necessary
less than a body workout. Ability to control one’s actions in extreme situations
situations and avoiding panic is one of the most important tasks of a freediver.

Never dive if you are cold or tired.

Cold, fatigue have a negative effect on holding the breath.
In addition, all this reduces the ability of self-control, thereby increasing the risk
occurrence of a blackout. If you feel tired or cold, don’t force yourself!
There will be a new day for new achievements.

Alcohol and drugs also negatively affect latency
breathing, create a feeling of unjustified self-confidence and sharply reduce
the ability to self-control, thereby increasing the risk of blackout.

Body hydration and nutrition for the freediver.

It is not recommended to dive for 3-4 hours after a full
meals and 1-2 hours after a light snack. The process of digestion requires
additional blood flow to the stomach, which significantly reduces the flow of blood to other
vital organs and makes it difficult to hold your breath.

Enhanced ventilation, prolonged exposure to water and
high energy consumption leads to dehydration of the freediver’s body. Dehydration
reduces the body’s ability to absorb oxygen, reducing the possibility of delay
breathing and increasing the risk of blackout. Therefore, during training
there should always be a supply of water, and freedivers should remember to replenish their moisture supply
in organism.

Do not try to increase your meters every day.

A freediver cannot be a super athlete every day and
every minute. It is very important to be able to listen to yourself, to your feelings and in
Depending on this, build your training regimen. Our body is wise
dynamic system. We cannot be at our peak every day.
A freediver is his own psychotherapist, his own director.

Scuba diver or diver? What is the difference?

Who are scuba divers?

Scuba is a device that allows a person to stay under water for a long time and dive to a considerable depth. Although the devices that allowed people to breathe and move in the water have been designed and used for several centuries, it was not until 1943 that two young Frenchmen Jacques Yves Cousteau and Emile Gagnan created an apparatus that was sufficiently effective and safe for this purpose. They called it scuba, from the Latin aqua (water) and the English lung (lung).

The difference between divers and scuba divers

It is logical that people who use scuba diving are called scuba divers. However, abroad, and in Russia, scuba divers are increasingly using the word divers instead of the word. This name comes from the English expression “to dive” – ​​to dive. Today it applies to both divers using special equipment and divers who do without it. Thus, scuba divers are scuba divers, and divers are divers in general. Some authors define the difference between scuba divers and divers as follows: scuba divers are professional swimmers, while divers are amateurs. However, this is an erroneous opinion.

Groups of divers

Today divers are divided into several groups based on the type of breathing and diving conditions:
– scuba diver – scuba diver (diver breathing underwater with the help of an aqualung).
– skindiver – diver with a mask and snorkel.
– technical diver specializing in diving in difficult conditions: great depth, caves, sunken objects, poor visibility, etc.
– a freediver – a diver who dives while holding his breath.

Scuba divers records

Unfortunately, there is no official generalized and time-tested information about the records that divers in general, and scuba divers in particular, have set at the moment. Therefore, the data below may need to be clarified.

– the longest stay under water – 220 hours. The record was set by Hu-Swee Chow, a scuba diver from Singapore in 2009.
– the most massive scuba dive. The record was set in 2009. 2861 scuba divers simultaneously took part in the dive.
– the deepest scuba dive – 330 meters The record was set in 2005 by the French scuba diver Pascal Bernabe.

Divers’ records

– the first dive record without scuba gear was recorded in 1949. Italian diver Raimondo Booker descended to a depth of 30 meters.
– Sicilian diver E. Mallorca set a world record in September 1974, reaching a depth of 87 meters!!! He was under water for 2 minutes 19 seconds.
– according to researchers, the duration of holding the breath of an adult normal person is at rest: after inhalation – 54.5 seconds, after exhalation – 40 seconds. Trained divers are able to hold their breath for 7.5 minutes.

Can I go diving?

Everything that has been described above is more about professional divers, but there is a huge squad of divers who go diving for their own pleasure.