What is decompression sickness. How does it occur. What are the main types and symptoms. How is decompression sickness treated. Who is at higher risk of developing this condition.

Understanding Decompression Sickness: A Deep Dive into ‘The Bends’

Decompression sickness (DCS), colloquially known as ‘the bends’, is a potentially life-threatening condition that occurs when dissolved gases, primarily nitrogen or helium, form bubbles inside the body during rapid depressurization. This phenomenon typically affects divers, caisson workers, and individuals exposed to significant pressure changes.

What Causes Decompression Sickness?

DCS results from a rapid decrease in ambient pressure, causing dissolved gases in body tissues to come out of solution and form bubbles. This process can occur during:

• Ascending too quickly from underwater diving
• Exiting a pressurized work environment (e.g., caisson)
• Flying in an unpressurized aircraft at high altitudes
• Engaging in extra-vehicular activity from spacecraft

The formation of these bubbles can lead to tissue damage through various mechanisms, including vascular blockage, spasm, and activation of inflammatory responses.

Types of Decompression Sickness: From Mild to Severe

Medical experts classify DCS into two main categories based on the severity and location of symptoms:

Type I Decompression Sickness

This milder form of DCS primarily affects the skin, musculoskeletal system, and lymphatic systems. Symptoms may include:

• Joint pain (commonly in shoulders, elbows, knees, and ankles)
• Skin rashes or itching
• Swelling in lymph nodes

Type II Decompression Sickness

The more severe form involves the central nervous system and can be life-threatening. Symptoms may include:

• Neurological issues (e.g., headaches, visual disturbances, paralysis)
• Respiratory problems (“the chokes”)
• Cardiovascular complications

Risk Factors: Who’s More Susceptible to ‘The Bends’?

While anyone exposed to rapid pressure changes can develop DCS, certain factors may increase the risk:

• Dehydration
• Presence of a patent foramen ovale (a heart defect)
• Previous injuries
• Cold ambient temperatures
• High body fat content
• Alcohol consumption
• Male gender (2.5 times higher risk than females)

Understanding these risk factors can help individuals take preventive measures and be more vigilant during activities that involve pressure changes.

Recognizing the Signs: How Does Decompression Sickness Present?

The symptoms of DCS can vary widely depending on the type and severity of the condition. Early recognition is crucial for prompt treatment and better outcomes.

Common Symptoms of Type I DCS

• Joint pain (“the bends”), especially in shoulders
• Skin manifestations (itching, rashes)
• Fatigue
• Swelling in lymph nodes

Symptoms of Type II DCS

• Neurological symptoms (headaches, confusion, paralysis)
• Visual disturbances
• Respiratory difficulties (“the chokes”)
• Extreme fatigue
• Loss of consciousness

It’s important to note that symptoms can appear immediately after surfacing or up to 24 hours later. Any unusual symptoms following exposure to pressure changes should be treated as potential DCS and evaluated promptly.

Diagnosing ‘The Bends’: From History to Physical Examination

Diagnosing DCS relies heavily on a detailed patient history and physical examination. Healthcare providers focus on:

• Exposure details (dive profile, gas mix used)
• Onset, duration, and progression of symptoms
• Comprehensive neurological examination
• Ear examination for signs of barotrauma

In some cases, additional tests such as chest X-rays, MRI, or ultrasound may be used to assess the extent of bubble formation and tissue damage.

Treatment Approaches: Managing Decompression Sickness

The primary treatment for DCS is recompression therapy using hyperbaric oxygen. This approach aims to reduce bubble size, improve tissue oxygenation, and promote the elimination of inert gases.

Immediate First Aid

• 100% oxygen administration
• Horizontal positioning of the patient
• Hydration (if conscious and not contraindicated)
• Rapid transport to a hyperbaric facility

Hyperbaric Oxygen Therapy

This treatment involves placing the patient in a pressurized chamber and administering 100% oxygen. The increased pressure helps to shrink gas bubbles and force them back into solution, while the high oxygen concentration promotes healing and reduces inflammation.

Adjunctive Treatments

• Intravenous fluids
• Pain management
• Anticoagulation therapy (in severe cases)
• Rehabilitation for neurological deficits

The effectiveness of treatment largely depends on the severity of symptoms and how quickly therapy is initiated. Early intervention significantly improves outcomes and reduces the risk of long-term complications.

Prevention Strategies: Minimizing the Risk of ‘The Bends’

While it’s impossible to eliminate the risk of DCS entirely, several strategies can help reduce its occurrence:

• Adhering to proper decompression procedures during diving
• Using dive computers to monitor ascent rates and decompression stops
• Avoiding alcohol consumption before and after diving
• Maintaining proper hydration
• Allowing sufficient surface intervals between dives
• Avoiding flying or ascending to altitude shortly after diving

For individuals working in pressurized environments or engaging in space activities, following established protocols and using appropriate equipment is crucial for preventing DCS.

The Role of the Interprofessional Team in Managing DCS

Effective management of decompression sickness requires a coordinated effort from various healthcare professionals:

• Emergency responders for initial assessment and treatment
• Hyperbaric specialists to oversee recompression therapy
• Neurologists to evaluate and manage neurological symptoms
• Physiotherapists for rehabilitation
• Diving medicine experts for prevention and education

This interprofessional approach ensures comprehensive care and improves outcomes for patients affected by DCS.

Future Directions: Advancing Our Understanding of ‘The Bends’

Research into decompression sickness continues to evolve, focusing on several key areas:

• Improving decompression algorithms for safer diving practices
• Developing more effective treatments for severe cases
• Investigating genetic factors that may predispose individuals to DCS
• Exploring the long-term effects of multiple DCS episodes
• Enhancing prevention strategies for high-risk activities

As our understanding of the pathophysiology and risk factors of DCS grows, we can expect to see advancements in prevention, diagnosis, and treatment strategies.

Can DCS be completely prevented?

While it’s challenging to eliminate the risk entirely, strict adherence to decompression protocols, proper training, and awareness of individual risk factors can significantly reduce the likelihood of developing DCS. However, even with perfect compliance, a small risk remains due to individual physiological variations and unpredictable factors.

Are there long-term effects of DCS?

In most cases, when treated promptly and appropriately, individuals with DCS recover fully. However, severe cases or those with delayed treatment may lead to long-term neurological deficits, chronic pain, or other persistent symptoms. Regular follow-up and rehabilitation can help manage these long-term effects.

How does altitude affect DCS risk?

Ascending to altitude, whether by flying or traveling to high-elevation areas, can increase the risk of DCS, especially after diving. The reduced atmospheric pressure at altitude can cause dissolved gases to come out of solution more readily. This is why divers are advised to wait at least 24 hours before flying after their last dive, depending on their dive profile.

What role does hydration play in preventing DCS?

Proper hydration is crucial in preventing DCS. Well-hydrated tissues can more effectively absorb and eliminate inert gases. Dehydration, on the other hand, can increase the risk of bubble formation. Divers and individuals working in pressurized environments are advised to maintain good hydration before, during, and after exposure to pressure changes.

How does body composition affect DCS risk?

Body composition, particularly the amount and distribution of body fat, can influence an individual’s susceptibility to DCS. Nitrogen is more soluble in fat than in other tissues, meaning individuals with higher body fat percentages may absorb more nitrogen during pressurization. This can potentially increase the risk of bubble formation during decompression. However, it’s important to note that DCS can occur in individuals of all body types, and other factors also play significant roles in determining risk.

What advancements are being made in DCS treatment?

Current research is exploring several promising areas for improving DCS treatment:

• Development of more effective oxygen delivery systems for first aid and transport
• Investigation of pharmacological interventions to reduce bubble formation and mitigate tissue damage
• Refinement of hyperbaric treatment protocols for different types and severities of DCS
• Exploration of novel biomarkers for early detection and severity assessment
• Advancement in portable hyperbaric chambers for remote locations

These advancements aim to improve treatment outcomes and reduce the long-term impacts of DCS, especially in severe cases or situations where immediate access to hyperbaric facilities is limited.

How does DCS differ in space environments?

Decompression sickness in space, often referred to as “spacewalker’s bends,” presents unique challenges:

• The vacuum of space creates an extreme pressure differential
• Microgravity affects fluid distribution in the body
• Limited medical resources are available for treatment
• Prolonged exposure to artificial atmospheres can alter gas saturation levels

Space agencies employ specialized protocols, including pre-breathing pure oxygen and using specific suit pressures, to minimize the risk of DCS during extra-vehicular activities. Research continues to optimize these procedures for long-duration space missions and potential planetary exploration.

What is the relationship between DCS and patent foramen ovale (PFO)?

A patent foramen ovale (PFO), a common heart defect where a small opening between the heart’s upper chambers fails to close after birth, has been associated with an increased risk of certain types of DCS, particularly those affecting the central nervous system. The PFO can allow venous gas bubbles to bypass the lungs and enter the arterial circulation, potentially leading to more severe manifestations of DCS. While not all individuals with PFO will experience DCS, and not all cases of DCS are related to PFO, divers diagnosed with this condition may be advised to take additional precautions or consider surgical closure in some cases.

How do dive computers contribute to DCS prevention?

Dive computers play a crucial role in modern diving safety and DCS prevention:

• Real-time tracking of depth, time, and ascent rates
• Calculation of tissue gas saturation based on complex algorithms
• Provision of customized decompression schedules
• Alerts for exceeding safe ascent rates or missed decompression stops
• Logging of dive profiles for post-dive analysis and future planning

While dive computers significantly enhance safety, they are tools that complement, rather than replace, proper training and judgment. Divers must understand the limitations of these devices and always err on the side of caution when interpreting their guidance.

What is the significance of “silent bubbles” in DCS research?

“Silent bubbles” refer to small gas bubbles that form in the body during or after decompression but do not cause immediate symptoms. Research into these asymptomatic bubbles has revealed several important insights:

• Their presence and quantity can be indicative of decompression stress
• They may contribute to long-term health effects in frequent divers
• Monitoring silent bubbles can help in developing more effective decompression strategies
• Individual variations in bubble formation may explain differences in DCS susceptibility

Advanced techniques like Doppler ultrasound are used to detect and quantify these bubbles, contributing to our understanding of DCS pathophysiology and risk assessment.

How does DCS affect marine mammals, and what can we learn from them?

Marine mammals, particularly deep-diving species like sperm whales and elephant seals, have evolved remarkable adaptations to avoid DCS despite rapid and deep dives. Studying these adaptations provides valuable insights:

• Collapsible lungs that reduce nitrogen uptake at depth
• Enhanced oxygen storage capabilities in blood and muscle
• Selective organ perfusion during dives
• Possible mechanisms for bubble resolution or prevention

Research into these natural adaptations may lead to novel approaches for preventing and treating DCS in humans, potentially inspiring new protective technologies or treatment modalities.

As we continue to explore the depths of our oceans and the vastness of space, understanding and managing decompression sickness remains a critical challenge. Ongoing research, technological advancements, and improved training protocols are essential in our quest to make these extreme environments safer for human exploration and work. By learning from nature, leveraging cutting-edge technology, and fostering international collaboration, we can hope to minimize the risks associated with rapid pressure changes and ensure the safety of divers, astronauts, and workers in pressurized environments.

Decompression Sickness – StatPearls – NCBI Bookshelf

Jeffrey S. Cooper; Kenneth C. Hanson.

Author Information and Affiliations

Last Update: September 2, 2022.

Continuing Education Activity

Decompression sickness (DCS) occurs when dissolved gasses (usually nitrogen or helium, used in mixed gas diving) exit solution and form bubbles inside the body on depressurization. DCS occurs from underwater diving decompression (ascent), working in a caisson, flying in an unpressurized aircraft, and extra-vehicular activity from spacecraft. Proper decompression procedures during diving can help decrease DCS. Experts have classified DCS as Type I with symptoms involving only the skin, musculoskeletal system, or lymphatic systems; and Type II with symptoms that involve the central nervous system. This activity reviews the presentation of decompression sickness and highlights the role of the interprofessional team in its management.

Objectives:

• Review the etiology of decompression sickness.

• Describe the presentation of decompression sickness.

• Summarize the treatment of decompression sickness.

• Outline the importance of improving care coordination among interprofessional team members to improve outcomes for patients affected by decompression sickness.

Access free multiple choice questions on this topic.

Introduction

Decompression sickness (DCS) occurs when dissolved gasses (usually nitrogen or helium, used in mixed gas diving) exit solution and form bubbles inside the body on depressurization. DCS occurs from underwater diving decompression (ascent), working in a caisson, flying in an unpressurized aircraft, and extra-vehicular activity from spacecraft. Proper decompression procedures during diving can help decrease DCS. Experts have classified DCS as Type I with symptoms involving only the skin, musculoskeletal system, or lymphatic systems; and Type II with symptoms that involve the central nervous system.

Etiology

DCS is bubble formation, growth, and elimination caused by a reduction in ambient pressure that results in inert gasses, usually nitrogen, that are dissolved in solution within tissues of the body. Individuals that breathe air in a pressurized environment reach a state of equilibrium/saturation of gas. This dissolved gas will be driven out of solution when leaving a higher-pressure environment to a lower pressure environment, such as ascending from depth during self-contained underwater breathing apparatus (SCUBA) diving, leaving a caisson worksite, or ascending to altitude in an unpressured aircraft. There are individual factors identified as possibly contributing to an increased risk of DCS. These include dehydration, patent foramen ovale,[1] previous injury, cold ambient temperature, high body fat content, and alcohol consumption. Type II decompression sickness (neurological symptoms) is thought to occur from right-to-left shunting of venous bubbles.[2]

Epidemiology

The incidence of decompression sickness, fortunately, is rare. Estimates for sports diving are three cases per 10,000 dives. The incidence among commercial divers can be higher ranging from 1.5-10 per 10,000 dives. As expected, the incidence depends on the length and depth of the dive.[3] The risk for DCS is 2.5 times greater for males than females.

Pathophysiology

The pathophysiology of DCS is due directly to the formations of bubbles coming out of solution. Tissue damage results from multiple mechanisms including blockage of blood flow and vascular spasm.[4] Gas bubbles also cause endothelial damage resulting in activation of the intrinsic clotting cascade with platelet activation. Inflammatory mediators are released and with increased endothelial permeability development of edema, which leads to tissue ischemia.[5]

History and Physical

The initial evaluation of a patient suspected of DCS should include a detailed history and physical exam. For a conscious patient, get the details of exposure, including onset, duration, and progression of symptoms. For a diver with DCS, it is vital to determine the patient’s dive profile and gas mix.[3] An ear exam should look for signs of barotrauma. The patient should have a detailed neurological exam. 

DCS occurs most frequently in the shoulders, elbows, knees, and ankles. Joint pain (“the bends”) accounts for most cases, with the shoulder being the most prevalent site. Neurological symptoms present in 10% to 15% of DCS cases with a headache and visual disturbances being the most common symptoms. Skin manifestations are a feature in about 10% to 15% of DCS cases. Pulmonary DCS (“the chokes”) is quite rare in divers and much less frequently seen in aviators because of oxygen pre-breathing protocols. Bubbles in the skin or joints result in mild symptoms, larger numbers of bubbles in the venous blood may cause lung damage, and bubbles involving spinal cord function may lead to paralysis, sensory dysfunction, or death. If there is a cardiac right-to-left shunt, (e.g., a patent foramen ovale), venous bubbles could potentially enter the arterial circulation, resulting in an arterial gas embolism.

DCS should be suspected if related symptoms occur following a drop in pressure within 24 hours of diving. The diagnostic confirmation is if the symptoms are relieved by recompression. Magnetic resonance imaging (MRI) or computed tomography (CT) can occasionally identify bubbles in DCS, but they are not good at determining the diagnosis and certainly cannot be used to rule out DCS.

Evaluation

DCS is a clinical diagnosis. As the goal for treating all patients with symptomatic DCS is hyperbaric oxygen (HBO), with emphasis placed on recompression, there should be no delay in treatment for further diagnostic workup. The one exception is a chest x-ray, as untreated pneumothoraces are an absolute contraindication for HBO.[3]

Treatment / Management

All decompression sickness cases should have initial treatment with 100% oxygen until HBO therapy is available. Neurological, pulmonary, and mottled skin lesions should be treated with HBO therapy even if seen several days after development. Fluid administration is indicated, as this helps minimize dehydration. The recommendation to administer aspirin is no longer valid, as analgesics may mask symptoms. Patient placement is in the supine position or the recovery position if vomiting occurs. The Trendelenburg position and the left lateral decubitus position (Durant’s maneuver) may be potentially beneficial if air emboli are suspected, but these positions are no longer recommended for extended periods, owing to concerns regarding cerebral edema. If the patient experiences an altered mental status or is unconscious, initial management should focus on the treatment and stabilization of ABCs, (airway, breathing, and circulation). Patients should receive HBO treatment as soon as possible.

Patients that need evacuation to a definitive treatment center by aeromedical transport should fly on pressurized aircraft. If unpressurized aircraft, such as helicopters, are the only means of transport then flight altitude should be limited to 300 m or 1000 ft if possible. [3]

Differential Diagnosis

Vertigo can indicate inner ear or vestibular decompression sickness wherein bubbles form in the perilymph fluid of the cochlea.[6] However, other diving-related causes merit consideration, as recompression and hyperbaric oxygen can cause worsening of some of these conditions. Inner ear barotrauma, in particular, would be a contraindication to compression as high-pressure gas may be forced into the cochlea causing further trauma on decompression. Alternobaric and caloric vertigo should be differentiated from decompression sickness by history. Cerebral arterial gas embolism affecting the midbrain or cerebellum can also present as inner ear decompression sickness but receives similar treatment.[1]

The differential diagnosis for divers should also consider that the stress of diving can exacerbate chronic medical problems. Consider cardiac disease for patients with chest pain and exacerbation of intrinsic lung disease for shortness of breath. Other considerations include pain from previous musculoskeletal injury and stroke and hypoglycemia for altered mental status.  Further concerns include drowning or near-drowning and thermal stress.[3]

Treatment Planning

There are a variety of hyperbaric chamber treatment protocols for decompression sickness. These differences are based on such things as the severity of the insult and the availability of oxygen. There are also in water recompression protocols. The usual US treatment protocol is a US Navy Treatment Table 6 done with oxygen pressurized to 2.8 atmospheres absolute (ATA). In water, recompression is a relatively high risk but is a consideration if there would otherwise be significant delays to treatment, logistical difficulties, or other problems. It requires appropriate training, equipment, and pre-planning. Immediate treatment at the surface with oxygen is beneficial for improving outcomes and decreasing recompression treatments.   

Treatment of DCS employing the US Navy Treatment Table 6 with oxygen at 18m is the standard of care. Significant delay to treatment, transportation difficulties, and facilities with limited experience may lead one to consider on-site treatment.  Surface oxygen for first aid is shown to improve the efficacy of recompression and decreased the number of recompression treatments required when administered less than four hours post-dive. In-water recompression (IWR) to 9m, breathing oxygen is one option that has shown success over the years. IWR is not without risk and requires certain precautions. IWR would only be suitable for an organized and disciplined group of divers with suitable equipment and practical training in the procedure.

Prognosis

Having had decompression sickness may place patients at increased risk for future similar events. Prognosis is severity dependent and also dependent on such factors as the time to recompression, availability and time to surface oxygen, and supportive care.

Complications

Decompression sickness can cause long-term damage. Central nervous system lesions in the spine and brain may occur.

Deterrence and Patient Education

The risk of decompression sickness is reducible in several ways. Divers should avoid flying within 24 hours after their last dive and longer no-fly periods may be required based on dive profiles and guided by decompression tables or computers. The use of oxygen-enriched gas can also ameliorate risk if used on “air tables.” Using a more conservative dive table or dive computer setting will likewise reduce risk. Isobaric decompression, breathing oxygen at depth, likewise can lessen the inert gas burden and reduce decompression sickness risk. 

Cold exposure, heavy exercise, recent alcohol use, and dehydration all increase risk and should be avoided. Preliminary research also shows that exercise several hours before diving may be protective while exercise after diving may increase the risk of DCS.[7]

Pearls and Other Issues

The treatment of DCS is with 100% oxygen, followed by recompression in a hyperbaric chamber.[8] In most cases, this will prevent long-term effects. However, permanent injury from DCS is possible. To prevent the excess formation of bubbles leading to decompression sickness, divers limit their ascent rate. The recommended ascent rate used by popular decompression models is about 10 meters (33 ft) per minute.

Enhancing Healthcare Team Outcomes

The management of patients with decompression sickness best done with an interprofessional team. Early identification and referral to a hyperbaric center are important for good outcomes from serious decompression sickness. In water, treatments need a well-trained and organized team approach.[9][10] Divers should have oxygen for immediate administration in the case of DCS. The Divers’ Alert Network provides referrals to hyperbaric facilities and 24/7 consultation with hyperbaric trained physicians and other providers.

Review Questions

• Access free multiple choice questions on this topic.

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References

1.

Livingstone DM, Smith KA, Lange B. Scuba diving and otology: a systematic review with recommendations on diagnosis, treatment and post-operative care. Diving Hyperb Med. 2017 Jun;47(2):97-109. [PMC free article: PMC6147252] [PubMed: 28641322]

2.

Clarke JR, Moon RE, Chimiak JM, Stinton R, Van Hoesen KB, Lang MA. Don’t dive cold when you don’t have to. Diving Hyperb Med. 2015 Mar;45(1):62. [PubMed: 25964043]

3.

Pollock NW, Buteau D. Updates in Decompression Illness. Emerg Med Clin North Am. 2017 May;35(2):301-319. [PubMed: 28411929]

4.

Geng M, Zhou L, Liu X, Li P. Hyperbaric oxygen treatment reduced the lung injury of type II decompression sickness. Int J Clin Exp Pathol. 2015;8(2):1797-803. [PMC free article: PMC4396314] [PubMed: 25973070]

5.

Hall J. The risks of scuba diving: a focus on Decompression Illness. Hawaii J Med Public Health. 2014 Nov;73(11 Suppl 2):13-6. [PMC free article: PMC4244896] [PubMed: 25478296]

6.

Mitchell SJ, Doolette DJ. Pathophysiology of inner ear decompression sickness: potential role of the persistent foramen ovale. Diving Hyperb Med. 2015 Jun;45(2):105-10. [PubMed: 26165533]

7.

Madden D, Thom SR, Dujic Z. Exercise before and after SCUBA diving and the role of cellular microparticles in decompression stress. Med Hypotheses. 2016 Jan;86:80-4. [PubMed: 26804603]

8.

Chin W, Joo E, Ninokawa S, Popa DA, Covington DB. Efficacy of the U.S. Navy Treatment Tables in treating DCS in 103 recreational scuba divers. Undersea Hyperb Med. 2017 Sept-Oct;44(5):399-405. [PubMed: 29116694]

9.

Mitchell SJ, Bennett MH, Bryson P, Butler FK, Doolette DJ, Holm JR, Kot J, Lafère P. Consensus guideline: Pre-hospital management of decompression illness: expert review of key principles and controversies. Undersea Hyperb Med. 2018 May-Jun;45(3):273-286. [PubMed: 30028914]

10.

Walker, III JR, Murphy-Lavoie HM. StatPearls [Internet]. StatPearls Publishing; Treasure Island (FL): May 1, 2023. Diving in Water Recompression. [PubMed: 29630272]

Disclosure: Jeffrey Cooper declares no relevant financial relationships with ineligible companies.

Disclosure: Kenneth Hanson declares no relevant financial relationships with ineligible companies.

Decompression Sickness – Harvard Health

What is it?

Decompression sickness, also called generalized barotrauma or the bends, refers to injuries caused by a rapid decrease in the pressure that surrounds you, of either air or water. It occurs most commonly in scuba or deep-sea divers, although it also can occur during high-altitude or unpressurized air travel. However, decompression sickness is rare in pressurized aircraft, such as those used for commercial flights.

When you scuba dive with compressed air, you take in extra oxygen and nitrogen. Your body uses the oxygen, but the nitrogen is dissolved into your blood, where it remains during your dive. As you swim back toward the surface after a deep dive, the water pressure around you decreases.

If this transition occurs too quickly, the nitrogen does not have time to clear from your blood. Instead, it separates out of your blood and forms bubbles in your tissues or blood. It is these nitrogen bubbles that cause decompression sickness. The condition is called the bends because the joint and bone pains can be so severe they double you over.

What happens inside your body during decompression sickness is similar to what happens when you open a carbonated drink. When you open the can or bottle, you decrease the pressure surrounding the beverage in the container, which causes the gas to come out of the liquid in the form of bubbles. If nitrogen bubbles form in your blood, they can damage blood vessels and block normal blood flow.

Factors that put you at higher risk of decompression sickness include:

• Heart muscle birth defects, including patent foramen ovale, atrial septal defect, and ventricular septal defect
• Being older than 30
• Being female
• Low cardiovascular fitness
• High percentage of body fat
• Use of alcohol or tobacco
• Fatigue, seasickness or lack of sleep
• Injuries (old or current)
• Diving in cold water
• Lung disease

Someone with an abnormal hole or opening in the heart from a birth defect is at especially high risk of developing serious symptoms from decompression illness. Because bubbles create high blood pressure in the lungs, blood and bubbles from your veins may flow more readily through the heart’s opening. This means your blood can re-circulate into arteries without first getting oxygen. An opening in the heart can also allow a relatively large air bubble (called an air embolism) to circulate into your arteries. An air embolism can cause a stroke.

People with asthma or another lung disease may have thin-walled air pockets in their lungs called bullae. These pockets do not empty quickly when the persons exhales. As they return to the surface after a deep dive, air in the bullae may expand. If a bulla ruptures, it could cause a collapsed lung or allow a large air bubble (air embolism) to enter the arteries.

Symptoms

Symptoms of decompression sickness include:

• Joint pain  
• Dizziness
• Headache
• Difficulty thinking clearly
• Extreme fatigue
• Tingling or numbness
• Weakness in arms or legs
• A skin rash

Diagnosis

Your diving history and symptoms are key factors in diagnosing decompression sickness. Blood tests and joint X-rays usually do not show any signs of the problem.

Expected duration

Joint pain, the most common symptom from decompression sickness, can last for days or weeks.

Prevention

To minimize the risk of decompression sickness while diving:

• Dive and rise slowly in the water, and don’t stay at your deepest depth longer than recommended. Scuba divers typically use dive tables that show how long you can remain at a given depth.
• Do not fly within 24 hours after diving.
• Don’t drink alcohol before diving.
• Avoid hot tubs, saunas or hot baths after diving.
• Make sure you are well hydrated, well rested and prepared before you scuba dive. If you recently had a serious illness, injury or surgery, talk to your doctor before diving.

Some people should avoid diving altogether, or should consider special risks. If you have a heart defect, it is not safe to dive. If you have asthma, a history of a ruptured lung at any time in your life or another lung disease, discuss diving safety with a doctor before deciding whether to dive. A person who requires insulin to treat diabetes may have wide swings in blood glucose levels during a dive, and caution is advised. Avoid diving if you have a groin hernia that has not been repaired, since expanding gas in the hernia can cause symptoms.

Treatment

Emergency treatment for decompression sickness involves maintaining blood pressure and administering high-flow oxygen. Fluids also may be given. The person should be placed left side down and if possible the head of the bed tilted down.

The optimal treatment is the use of a hyperbaric oxygen chamber, which is a high-pressure chamber in which the patient receives 100% oxygen. This treatment reverses the pressure changes that allowed gas bubbles to form in the blood stream. The treatment drives nitrogen back into its liquid form so that it can be cleared more gradually from the body over a period of hours.

It is not recommended that divers with decompression sickness attempt to treat themselves with deep diving.

When to call a professional

If you experience symptoms of decompression sickness after scuba diving or flying, get to a doctor as soon as you can. Hyperbaric treatment is most successful if given within several hours after symptoms start.

Prognosis

Most cases of decompression sickness respond well to a single treatment with hyperbaric oxygen. Your doctor may suggest repeated treatments if you continue to experience symptoms, especially neurological symptoms.

Additional info

Undersea & Hyperbaric Medical Society

https://www.uhms.org/

Nitrogen Narcosis: What Divers Need to Know

By Megan Danny November 18, 2022

Nitrogen narcosis is a mysterious condition that affects scuba divers and, in rare cases, even freedivers. There are other names for nitrogen narcosis: “deep delight”, “martini effect” and “deep intoxication”. However, on a dive boat, you will most likely just hear something like: “ Have you ever been anesthetized? »

What is nitrogen narcosis?

Simply put, it is the anesthetic effect caused by breathing compressed gas at depth, usually nitrogen. The National Institutes of Health (NIH) gives a more detailed definition.

Divers should be able to recognize the symptoms of nitrogen narcosis in themselves or their dive buddy. According to experts from the Divers Alert Network (DAN), the most common symptoms include the following:

• Impaired normal thought process
• Difficulty concentrating
• Drowsiness
• Self-confidence and euphoria
• Feeling of fear

How does nitrogen anesthesia feel?

First of all, nitrogen narcosis deprives you of the ability to reason and make intelligent decisions. At the same time, when you just go with the flow, not making any decisions and not completing any tasks, you may not realize that you have some kind of mental disorder. Many divers have been exposed to anesthesia without even knowing it.

Next comes the feeling of euphoria. Divers liken the feeling to being slightly drunk or getting a dose of “laughing gas” (nitrous oxide) from the dentist, but nitric narcosis works a little differently for everyone. Some divers, myself included, feel anxiety and pessimism instead of joy.

At this point, if the diver is unaware that he is under anesthesia and continues to descend, he may begin to have difficulty with physical coordination. Now the situation is getting very dangerous. Further descent to the depth can cause hallucinations, fixation on some individual obsessions, stupor and much more.

What you can do to detect nitrogen narcosis

Recognizing and avoiding intoxication at depth is an important safety skill. That’s why the PADI ^® Deep Diver Specialty Course includes an activity that allows divers to measure and evaluate the disturbances in normal thinking that occur with increasing depth. You will complete a task on the surface that requires reflection, such as a math problem or solving a simple puzzle. Personally, I liked to use one of these toys with holes of various shapes (where you need to insert figures in the form of a circle, triangle, etc.).

Under water, the instructor will ask you to repeat the task at a depth of at least 18 m, but with slight differences. If on the surface the instructor asked you to subtract two large numbers, then under water these numbers will be different. I usually ask my students to fold triangular shapes into a ball on the surface, and then fold the shapes into a circle underwater.

Your instructor will record how long it will take you to complete both tasks. As you go deeper, you may find that the task seems more confusing or takes longer to complete. The purpose of this activity is to help you understand how nitrogen anesthesia can affect you. This is one of several important things you will learn in the PADI Deep Diver course.

Other frequently asked questions

Is nitrogen narcosis the same as decompression sickness?

No, it’s not. Both conditions are caused by breathing compressed air that includes nitrogen, but decompression sickness and nitrogen narcosis are not the same thing. Learn more about how to spot decompression sickness.

At what depth does nitrogen narcosis occur?

Every human body is different. Some people love spicy food, while others can’t stand it. I’ve been bitten by mosquitoes on six continents, leaving red spots, and my partner is completely immune. Nitrogen anesthesia is no different. Some divers feel the effect as early as 30 meters, while others feel nothing until they reach the recreational limit of 40 meters.

You might be wondering if the use of a gas mixture with a lower nitrogen content, such as enriched air, reduces the risk of anesthesia ? According to recent research, no. In addition, when using enriched air at depths below 30 meters, there is a risk of oxygen intoxication. Learn more on the PADI Enriched Air Diver course.

How is nitrogen anesthesia treated?

The diver or his dive buddy must first recognize the symptoms. The next step is to ascend slowly until the diver feels normal again.

How long does nitrogen anesthesia last?

The diver should begin to feel normal within a few minutes after ascending to a shallower depth. If symptoms persist, stop diving and seek medical attention.

Is it possible to experience anesthesia while freediving?

According to Akim Ladhari, PADI AmbassaDiver™ and founder of Blue Immersion Freediving, nitrogen narcosis can happen to freedivers too. Most often this happens when diving to a depth of more than 70 meters.

Why does nitrogen narcosis occur?

Scientists haven’t figured out the cause completely, 100 percent, but they have identified some factors that increase the likelihood of its occurrence:

• Depth
• Fatigue
• Drinking alcohol before diving
• Cold water/hypothermia
• Nervousness

The easiest way to avoid nitrogen narcosis is to limit your diving depth to 30 meters or less, especially if you feel tired, anxious or have had a drink the day before. In the PADI Deep Diver Specialty Course, you will learn how to recognize and prevent nitrogen narcosis, as well as many other useful things.

Experience deep diving with a PADI Instructor. Watch the video below or contact your Instructor or PADI Dive Center/Resort for more information.

LEARN MORE ABOUT THE DEEP DIVER COURSE

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less dangerous disease among lovers of the underwater world is nitrogen poisoning. Divers also refer to it as depth sickness or nitrogen narcosis.

After doing some research, scientists came to the conclusion that
at a certain concentration of nitrogen, it tends to act as
intoxicant. Its toxic effect is due to the dissolution of nitrogen
cells in fats and metabolic disorders in the human body. Also for deep
diseases are characterized by a decrease in the speed of attention, dullness of feelings
self-preservation, inhibition of thinking.

Why does
nitrogen narcosis

The main cause of nitrogen poisoning is
use of oxygen mixture by divers
diving, during which there is a toxic effect on the human brain.
Increasing the diving depth by more than 45 meters can cause an attack
euphoria or causeless excitement and panic.

The psychological state of the diver directly affects
progression of nitrogen disease. If a person is dejected, then in the depths of the sea
he will experience nothing but anxiety and fear. Very fast dive
water causes an increase in sensations of deep illness, as well as
cold water or alcohol intoxication.

Features
diseases

Among the many water activities, diving is considered one of the most unsafe activities. Underwater lovers can
experience a variety of sensations under the influence of the so-called nitrogen
– from mild drug intoxication to impaired coordination of movements and even
memory loss. Memory problems, inappropriate behavior, gaiety,
hallucinations occur in those divers who, when
dived down to a depth of 50-60 m.

For those who decide to take up water sports in a depressed
able, and even dive to a depth of more than 70 m, are characterized by uncontrolled
feeling of fear, panic attacks, prostration, increased anxiety.
The effect of nitrogen on the body is so strong that at great depths (80-100 m)
may cause narcotic sleep, which may be accompanied by loss of consciousness
and even cardiac arrest.

Rendering Tips
first aid and preventive measures

At the first manifestations of a deep illness, it is necessary
stop the diver’s descent. In most cases, all signs of nitrogen narcosis
pass after raising a person to a depth of about 40 m. If signs of illness
have not disappeared, it is necessary to raise the victim to the surface and provide him
air access by freeing from equipment and restraining uniforms.