What are the symptoms of decompression sickness in scuba diving. How can divers prevent the bends. What is the proper treatment for decompression sickness. Why do nitrogen bubbles form during rapid ascents. When should divers seek medical attention after diving.

What Is Decompression Sickness (The Bends) in Scuba Diving?

Decompression sickness, commonly known as “the bends,” is a potentially serious condition that can affect scuba divers. It occurs when dissolved gases, primarily nitrogen, form bubbles in the blood and tissues as a diver ascends too quickly from depth. These bubbles can cause a range of symptoms, from mild discomfort to life-threatening complications.

The term “the bends” originates from the characteristic posture adopted by early caisson workers suffering from decompression sickness. They would often bend forward at the waist due to joint pain, hence the name.

The Science Behind Decompression Sickness

To understand decompression sickness, we need to delve into the physics and physiology of diving:

• As divers descend, the increased pressure causes more nitrogen to dissolve in their body tissues.
• During ascent, this dissolved nitrogen must be released slowly to prevent bubble formation.
• If a diver ascends too quickly, the rapid pressure change can cause nitrogen to come out of solution too fast, forming bubbles.

These bubbles can obstruct blood flow, cause tissue damage, and interfere with normal bodily functions, leading to the various symptoms associated with decompression sickness.

What Are the Symptoms of Decompression Sickness?

Recognizing the symptoms of decompression sickness is crucial for prompt treatment. Symptoms can vary widely in severity and may appear immediately after surfacing or up to 24 hours later. Common signs include:

• Joint pain, often in the elbows, knees, or shoulders
• Muscle aches
• Fatigue or weakness
• Skin rashes or itching
• Dizziness or vertigo
• Numbness or tingling sensations
• Shortness of breath
• Chest pain
• Confusion or memory problems
• In severe cases, paralysis or loss of consciousness

Is it possible for symptoms to appear long after diving? While most symptoms occur within 6 hours of surfacing, some divers may experience delayed onset decompression sickness up to 48 hours after a dive. This is why divers are advised to wait at least 24 hours before flying after their last dive.

How Can Divers Prevent Decompression Sickness?

Prevention is always better than cure when it comes to decompression sickness. Here are some essential strategies divers can employ to minimize their risk:

1. Follow dive tables or computer recommendations strictly
2. Ascend slowly and make safety stops
3. Avoid pushing no-decompression limits
4. Stay well-hydrated before, during, and after diving
5. Avoid alcohol and strenuous exercise before and after diving
6. Maintain good physical fitness and a healthy weight
7. Wait at least 24 hours after diving before flying

Can diving conservatively eliminate all risk of decompression sickness? While these precautions significantly reduce the risk, it’s important to note that even when following all guidelines, a small risk of decompression sickness still exists. This is why divers should always be vigilant and prepared to recognize and respond to symptoms.

The Role of Dive Computers in Prevention

Modern dive computers play a crucial role in preventing decompression sickness. These devices continuously calculate a diver’s nitrogen absorption and provide real-time information on:

• Current depth and dive time
• No-decompression limits
• Ascent rate warnings
• Decompression obligations, if any
• Surface interval times between dives

By following the guidance provided by dive computers, divers can significantly reduce their risk of decompression sickness. However, it’s essential to understand that these devices are tools, not guarantees, and should be used in conjunction with proper training and judgment.

What Is the Treatment for Decompression Sickness?

If decompression sickness is suspected, prompt action is crucial. The primary treatment involves:

1. Administering 100% oxygen
2. Rehydration
3. Transportation to the nearest hyperbaric chamber

Hyperbaric oxygen therapy is the definitive treatment for decompression sickness. This involves placing the patient in a pressurized chamber where they breathe pure oxygen. The increased pressure helps reduce bubble size and promotes the elimination of excess nitrogen from the body.

How long does hyperbaric treatment typically last? Treatment duration can vary depending on the severity of symptoms, but initial treatments often last between 4 to 6 hours. Some cases may require multiple treatments over several days.

First Aid for Suspected Decompression Sickness

While awaiting professional medical care, the following first aid measures can be taken:

• Provide 100% oxygen if available
• Keep the patient lying flat and encourage them to remain still
• Provide water to drink, unless nausea is present
• Monitor vital signs and be prepared to perform CPR if necessary
• Contact local emergency services or the nearest diving medicine specialist

It’s important to note that even mild symptoms should be taken seriously, as they can potentially worsen if left untreated.

What Factors Increase the Risk of Decompression Sickness?

While any diver can potentially experience decompression sickness, certain factors can increase the risk:

• Age: Older divers may have reduced circulatory efficiency
• Body composition: Higher body fat percentage can increase nitrogen absorption
• Dehydration: Reduces blood flow and nitrogen elimination
• Cold water diving: Can affect circulation in extremities
• Repetitive diving: Multiple dives in a short period can lead to nitrogen buildup
• Rapid ascents or missed decompression stops
• Flying too soon after diving
• Previous history of decompression sickness
• Alcohol consumption before or after diving
• Intense exercise immediately after diving

Understanding these risk factors can help divers make informed decisions about their diving practices and take appropriate precautions.

The Impact of Physical Fitness on Decompression Risk

Physical fitness plays a significant role in a diver’s susceptibility to decompression sickness. Here’s how it affects risk:

• Improved cardiovascular health enhances nitrogen elimination
• Better muscle tone and lower body fat reduce nitrogen absorption
• Increased lung capacity can improve gas exchange efficiency
• Enhanced overall fitness allows for better stress management underwater

While fitness alone doesn’t guarantee protection against decompression sickness, maintaining good physical condition can certainly contribute to safer diving practices.

How Does Altitude Affect Decompression Sickness Risk?

Altitude can significantly impact a diver’s risk of developing decompression sickness, both during and after diving. This is due to the reduced atmospheric pressure at higher altitudes, which can exacerbate the effects of nitrogen bubbles in the body.

Diving at Altitude

When diving at altitude (typically considered any elevation above 300 meters or 1000 feet), divers must use special altitude dive tables or dive computers with altitude settings. These adjustments account for the lower atmospheric pressure and help prevent decompression sickness.

Flying After Diving

The risk of decompression sickness is also increased when flying soon after diving. As aircraft cabins are pressurized to an altitude equivalent of about 2,400 meters (8,000 feet), residual nitrogen in a diver’s tissues can form bubbles during flight.

To mitigate this risk, divers are advised to follow these guidelines:

• Wait at least 12 hours before flying after a single no-decompression dive
• Wait at least 18 hours after multiple dives or multiple days of diving
• Wait at least 24 hours after any dive requiring decompression stops

These waiting periods allow sufficient time for the body to eliminate excess nitrogen, reducing the risk of bubble formation during flight.

What Role Does Hydration Play in Preventing Decompression Sickness?

Proper hydration is a crucial yet often overlooked factor in preventing decompression sickness. Adequate fluid intake before, during, and after diving can significantly reduce a diver’s risk of developing this condition.

How Hydration Affects Nitrogen Elimination

Staying well-hydrated helps in several ways:

• Improves blood circulation, aiding in nitrogen elimination
• Helps maintain proper blood volume, reducing the risk of bubble formation
• Supports optimal kidney function, which assists in removing waste products
• Reduces blood viscosity, allowing for better microcirculation in tissues

Dehydration, on the other hand, can impair the body’s ability to off-gas nitrogen effectively, increasing the risk of bubble formation and decompression sickness.

Hydration Best Practices for Divers

To ensure proper hydration, divers should:

1. Drink plenty of water in the 24 hours leading up to a dive
2. Avoid alcohol and caffeinated beverages before diving, as these can be dehydrating
3. Sip water between dives during surface intervals
4. Continue to hydrate after the dive day is complete
5. Be aware that immersion in water, even if not actively swimming, can lead to increased urination and potential dehydration

By maintaining good hydration practices, divers can significantly enhance their body’s ability to manage nitrogen loading and reduce their risk of decompression sickness.

How Does Technical Diving Affect Decompression Sickness Risk?

Technical diving, which often involves deeper and longer dives than recreational scuba diving, presents unique challenges and increased risks for decompression sickness. Understanding these risks is crucial for technical divers to plan and execute their dives safely.

Factors Contributing to Increased Risk in Technical Diving

Several aspects of technical diving contribute to a higher risk of decompression sickness:

• Greater depths lead to increased nitrogen absorption
• Longer bottom times result in more significant nitrogen loading
• More complex dive profiles often push closer to decompression limits
• Use of mixed gases can complicate decompression procedures
• Increased physical and mental stress during long, deep dives

Risk Mitigation Strategies for Technical Divers

To manage these increased risks, technical divers employ several strategies:

1. Extensive training and experience building
2. Use of specialized equipment, including redundant systems
3. Careful dive planning, including detailed decompression schedules
4. Conservative approach to dive limits and safety margins
5. Use of helium-based gas mixes to reduce narcotic effects and optimize decompression
6. Strict adherence to planned depth and time limits
7. Extended and/or deeper decompression stops

While these practices significantly reduce risk, it’s important to note that technical diving inherently carries a higher risk of decompression sickness compared to recreational diving. Technical divers must be prepared to manage this risk through proper training, planning, and execution of their dives.

The Importance of Proper Gas Management

In technical diving, proper gas management is critical not only for breathing supply but also for decompression safety. Divers must carefully plan their gas usage to ensure they have sufficient breathing gas for the planned dive profile, all required decompression stops, and potential emergencies.

This often involves carrying multiple tanks with different gas mixtures optimized for various phases of the dive, including:

• Bottom gas for the main portion of the dive
• Travel gas for descent and initial ascent
• Decompression gases with higher oxygen content for more efficient decompression

Proper use of these gases, along with precise dive execution, helps technical divers manage their decompression obligation and reduce the risk of decompression sickness even in challenging dive conditions.

What are ‘The Bends’? | 4/6/18

‘The Bends’, or decompression sickness to give its proper name, is one of the few dangers to be aware of when scuba-diving. Every diver out there dreads The Bends, and we all take a number of precautions to help keep it at bay every single time we dive – but what exactly is it and how do we avoid it?

Decompression Sickness

When on a normal recreational air-dive, the scuba diver is breathing in approximately 79% nitrogen and 21% oxygen. As we dive deeper, the increased pressure means this nitrogen is absorbed into our body tissue. This isn’t a problem for our bodies when we’re under these pressures, but if that pressure is reduced too quickly the nitrogen can form bubbles which enter the bloodstream and tissues, leading to The Bends. It’s similar to what happens with a fizzy soft drink – when the pressure is released by when it’s opened, bubbles are quickly formed. If you think about how violently gas explodes out of a shaken can or bottle, you get a sense of the potential damage that can be done to the body.

The most common way of getting The Bends (named due to the pain often felt in the joints of your arms or legs) is by going over the decompression limits set on your dive computers or tables, or getting too close to them. However it can also occur even when the diver has followed all the guidelines on the odd occasion.

The bubbles that enter the body tissues lead to a range of symptoms, which usually emerge soon after you surface. Pain is often the first sign, usually in the joints and muscles. Other symptoms include unpleasant itchiness, skin rashes (caused by bubbles in and under the skin) as well as headaches, dizziness, visual impairment, confusion, problems with balance/coordination and nausea. In cases with a great amount of bubbles, lungs can become congested and even brain damage and heart attacks or death can occur.

How to avoid The Bends?

The best way to avoid it is to religiously follow the recommended rate of ascent set by your dive computers!  Failing that treatment comes in the form of painkillers for very mild cases, having the divers breathe pure oxygen (which helps speed up the rate that the nitrogen leaves your body), or the use of a hyperbaric or recompression chamber, which expose the sufferer to high pressure causing the nitrogen bubbles to safely leave the tissues.

Finally you should avoid flying within 24 hours of your last dive, as aircraft that are not fully pressurised at altitude can cause nitrogen bubbles to form, even if there was no problems before the flight.

 Fisherman Alejandro Ramos Martinez with the funniest ‘Bend’ ever

Other Things Keep The Bends Away

• Never dive right to the limits set by you dive computer, it’s best to always start your ascent at least a few minutes before you reach them.

• The older you are, the less efficient your circulatory system becomes less efficient, which affects the elimination of nitrogen.

• If you’re a bit of a fatty (or big-boned like me) you should know that nitrogen dissolves easily into fat tissue, so chubby funsters may absorb more nitrogen when diving.

• Diving in cold water can cause your extremities to receive less circulation as they cool, which also effects nitrogen elimination.’

• Don’t dive drunk or high! This is something we should never be doing anyway as your judgement will definitely be impaired, but it also makes you dehydrated and raises the heart rate, increasing the risk of those pesky bubbles forming.

• Taking a hot shower or bath after a dive cause your capillaries to dilate, which will draw blood away from other areas which then eliminate nitrogen more slowly.

Safe diving folks!

Treating Decompression Sickness (The Bends)

Decompression sickness (DCS) is one of the most common problems reported to Divers Alert Network® (DAN®). Although scuba diving accidents are rare, it’s important to know how to handle suspected cases of DCS. Your ability to take appropriate action can make a difference in the life of someone you care about.

What is Decompression Sickness?

DCS, also known as the bends, describes a variety of injuries that result from inadequate decompression following exposure to increased pressure. This can occur following uneventful dives within accepted no-decompression limits but is more likely after dives that involve a rapid underwater ascent. DCS can also be prompted by ascending in an airplane too soon after diving. When there is a rapid decrease in surrounding pressure, nitrogen absorbed by the body at depth comes out of solution, creating bubbles in the bloodstream and/or body tissues.

Symptoms of DCS can occur immediately after surfacing or up to 24 hours later. On average a diver with DCS will experience symptoms between 15 minutes and 12 hours following a dive.

Symptoms of DCS 

• Unusual fatigue
• Itchy skin
• Pain in the joints and/or muscles of the arms, legs or torso
• Dizziness, vertigo and ringing in the ears
• Numbness, tingling and paralysis
• Shortness of breath

Signs of DCS

• Blotchy rash
• Muscle weakness or paralysis
• Difficulty urinating
• Confusion, personality changes or bizarre behaviour
• Staggering
• Coughing up bloody, frothy sputum
• Collapse or unconsciousness

How to Treat a Diver with Suspected DCS

If you suspect a diver has DCS, provide emergency oxygen right away. Next, determine the severity of their condition (emergency, urgent or timely) by following the guidelines below:

Emergency DCS

A diver who is profoundly dizzy, intermittently conscious, weak, walking with an abnormal gait or having trouble breathing is experiencing a serious medical emergency. Administer 100 percent oxygen, and arrange emergency evacuation to the nearest medical facility.

Always contact emergency medical services first, then contact DAN. Although a diver with severe DCS requires recompression, it is essential that he or she be stabilised at the nearest medical facility before transportation to a chamber.

Urgent DCS

A diver experiencing severe pain that is either constant or increasing should be placed on 100 percent oxygen and given fluids. The next step is to contact DAN or the nearest medical facility. Emergency air transportation may not be necessary in all cases. Do not give the diver analgesics (pain relievers) unless advised to do so by medical personnel.

After obtaining professional medical advice, conduct a neurological exam and write down as much information as you can about the diver’s recent diving activity. A neurological exam can be done by anyone; no medical experience or training is required. Simply follow the on-site neuro exam directions found here. Ask the diver about any diving activities within the past 48 hours, including depths, times, ascent rates, surface intervals, breathing gas used and any problems experienced during or after the dives.

Obtain as much info as you can without delaying transportation to a medical treatment facility. If time allows, the following additional information may aid medical professionals with diagnosis and treatment:

• Symptom onset times and progression after the diver surfaced from their last dive
• A list of all first aid measures taken (including times and method of oxygen delivery) and their effect on symptoms
• A description of any joint or other musculoskeletal pain including location, intensity and changes based on movement or weight-bearing maneuvers
• Photos of any rashes with a detailed description of their location
• Information about any traumatic injuries sustained before, during or after the dive

Timely Cases of DCS

Divers who do not have obvious symptoms or whose symptoms develop slowly over multiple days may have a “timely” case of the bends. Common signs and symptoms may include vague complaints of pain or abnormal sensations.

Follow the steps described previously under “Urgent DCS” to conduct a neurological assessment and collect information about the diver’s recent activity. Next, contact DAN or a medical professional, or go to the nearest medical facility for advice and further evaluation.

Denial: The Worst Symptom of DCS

Denial is arguably the worst “symptom” of DCS. Delayed treatment can lead to permanent injury and prolong (or even prevent) the diver’s full recovery. Emergency oxygen can cause symptoms to temporarily improve only to reappear later — it is no substitute for a medical evaluation. Always contact DAN or a medical professional with training in dive medicine in cases of suspected DCS — even if the symptoms and signs appear to have resolved.
 
Be Prepared, Get Insured

Dive accidents can happen to anyone, not just newly certified divers. According to a recent DAN Annual Diving Report, nearly 600 divers contacted DAN with concerns about DCS, and divers with 21-60 logged dives were the most likely to report a diving incident. Learn more about the Top 5 Factors That Increase a Diver’s Risk of Getting the Bends.

Many medical insurance plans cover only the cost of hyperbaric treatments and not the cost of getting you to the chamber (the average cost for an air ambulance is around US$20,000). Ensure you have protection against the unexpected by purchasing DAN Dive Accident Coverage.  

Diving fin selection

How to choose a snorkel, professional advice

One of the first items that people began to use when exploring the underwater world were breathing snorkels. In the distant past, they were most often made from an ordinary reed stem. Modern models are far superior to them in terms of complexity and variety of design options. To make scuba diving safe and enjoyable, it is important to choose the right snorkel from the large range of models available in our online store.

When making a choice, first of all, consider the application of the accessory you are purchasing.

Scuba Diving

Experience has shown that scuba divers are most comfortable with varieties that have a corrugated segment, such as the Cressi ALFA DRY model. This part allows you to quickly and safely switch from the tube to the device and vice versa while underwater. In addition, the corrugated insert will make it possible to securely hold the tube during diving.

The purchased model must be fixed on the left side of the mask using a special fastener. Fixing under the mask strap when scuba diving is unacceptable: this method dramatically increases the risk of losing the tube.

Pay attention to the fact that the accessory you buy has a silicone mouthpiece, its curve is anatomical, and the shape of the section is an ellipse. A reflector nozzle and bypass valve will be useful.

Underwater swimming (snorkeling)

Scuba is not used in this case, and it is the snorkel that comes to the fore. We recommend opting for a simple model with a rotating silicone mouthpiece, the supply of which is located on the side.

It is important that the mouthpiece design is anatomical, such as that of the IST Favorit Dry model. In this case, the jaws will be less tired, and swimming will be comfortable. Silicone mouthpieces are rightfully considered the most convenient. Rubber varieties are inferior to them in terms of comfort, but last longer.

Pay special attention to snorkel models that allow the replacement of a damaged (e.g. bitten) mouthpiece.

Spearfishing

In this case, the swimmer should be as inconspicuous as possible for the aquatic life, which means that a dark-colored tube is best. A good choice would be a model with a valve that closes the entrance to the tube and eliminates the appearance of gurgling bubbles – for example, IST Saracin.

Snorkel retention requirements for spearfishing are not as stringent as for scuba diving. Many hunters attach an accessory to the mask strap without using additional devices, and in this case this cannot be considered a mistake.