What Happens to Your Body During Decompression Sickness?

Decompression sickness (DCS), commonly known as “the bends,” is a potentially dangerous condition caused by rapid pressure changes, affecting scuba divers, aviators, astronauts, and compressed-air workers. When a person moves from a high-pressure environment to a low-pressure environment too quickly, the nitrogen gas absorbed by the body under pressure forms gas bubbles in the bloodstream and tissues. These bubbles can obstruct blood flow, cause severe pain, neurological issues, and even life-threatening complications.

Understanding what happens to your body during DCS, its causes, symptoms, treatment, and prevention methods is crucial for ensuring safety in deep-sea diving, high-altitude aviation, and space missions.

What is Decompression Sickness?

Decompression sickness (DCS) occurs when dissolved nitrogen gas in body tissues forms bubbles due to rapid pressure reduction. These nitrogen bubbles can cause joint pain, dizziness, nerve damage, and even life-threatening conditions like arterial gas embolism.

Causes of Decompression Illness

• Rapid Ascents in Diving – The most common cause, where divers surface too quickly, preventing nitrogen from escaping safely.
• Flying After Diving – Air travel within 12-24 hours post-dive can lead to DCS due to lower atmospheric pressure.
• Repeated Deep Dives – Multiple dives within a short time increase nitrogen accumulation.
• High-Altitude Exposure – Pilots and astronauts exposed to rapid altitude changes without proper pressurization can develop DCS.
• Medical Conditions & Lifestyle Factors – Obesity, dehydration, excessive alcohol consumption, and lung or heart diseases elevate the risk.

How DCS Affects the Body: Symptoms & Risks?

The Role of Nitrogen in the Body

When breathing compressed air underwater, nitrogen dissolves into body tissues. Under normal conditions, a slow and controlled ascent allows this nitrogen to safely escape through exhalation. However, if a diver ascends too quickly, the sudden pressure change forces nitrogen to form gas bubbles in the bloodstream and tissues. These bubbles can cause blockages, tissue damage, and life-threatening complications.

How Gas Bubbles Impact Different Body Systems?

Nervous System (Neurological Decompression Sickness – DCS)

• Symptoms: Headache, dizziness, confusion, memory loss, paralysis, seizures.
• Effects: Gas bubbles in the spinal cord and brain can disrupt nerve function, leading to numbness, muscle weakness, coordination loss, and cognitive impairment. In severe cases, it can cause permanent nerve damage or stroke-like symptoms.

Musculoskeletal System (Joint & Muscle Pain – “The Bends”)

• Symptoms: Joint and muscle pain, stiffness, swelling.
• Effects: Bubbles trapped in joints and muscles trigger severe pain, particularly in weight-bearing areas like shoulders, elbows, knees, and hips. This is one of the most common and painful manifestations of DCS.

Circulatory System (Cardiovascular Decompression Sickness)

• Symptoms: Chest pain, difficulty breathing, irregular heartbeat.
• Effects: Large nitrogen bubbles can obstruct blood flow, leading to low blood pressure, heart stress, and even cardiac arrest. If bubbles enter the lungs, they can cause pulmonary embolism—a life-threatening condition that affects oxygen circulation.

Skin & Lymphatic System (Cutaneous Decompression Sickness)

• Symptoms: Rash, itching, swollen lymph nodes, skin mottling (marbled appearance).
• Effects: Bubbles trapped in small blood vessels near the skin result in painful rashes, swelling, and discoloration. In some cases, lymphatic blockages can cause fluid retention and swelling in extremities.

Symptoms of The Bends (DCS)

Decompression sickness symptoms can range from mild discomfort to life-threatening medical emergencies.

Mild to Moderate Symptoms of The Bends

These symptoms may appear within minutes to hours after surfacing and often worsen over time:

1. Joint & Muscle Pain (“The Bends”)

• One of the most common symptoms, typically affecting the shoulders, elbows, knees, and hips.
• Caused by nitrogen bubbles forming in joints, leading to stiffness, soreness, and deep aching pain.

2. Dizziness, Fatigue & Nausea

• Sudden lightheadedness or exhaustion post-dive may indicate circulatory or neurological effects of DCS.
• Some divers experience vertigo (loss of balance), making movement difficult.

3. Skin Rash, Itching & Swelling (Cutaneous DCS)

• Red, mottled skin (marbled appearance) and itchy rashes occur due to nitrogen bubbles forming in tiny blood vessels.
• In some cases, swelling and tenderness may develop around lymph nodes.

4. Mild Breathing Difficulty

• Shortness of breath can occur due to minor gas buildup in the lungs and bloodstream.
• If breathing issues worsen, it could indicate a more severe form of DCS affecting the cardiovascular system.

Severe Symptoms of DCS (Life-Threatening)

If left untreated, DCS can progress to severe neurological, cardiovascular, and respiratory complications requiring immediate emergency care.

1. Neurological Symptoms (Brain & Spinal Cord Damage)

• Confusion & Memory Loss – Cognitive impairment may indicate reduced blood flow to the brain.
• Slurred Speech & Difficulty Walking – Signs of brain dysfunction due to nitrogen bubbles in the central nervous system.
• Paralysis or Numbness – Partial or complete loss of sensation or movement in limbs can occur if spinal cord function is affected.

2. Cardiovascular Symptoms (Heart & Blood Flow Issues)

• Chest Pain & Irregular Heartbeat – Gas bubbles in the bloodstream can cause heart strain, abnormal rhythms, and possible cardiac arrest.
• Unconsciousness or Shock – Severe cases may lead to loss of consciousness due to low oxygen levels and circulatory collapse.

3. Severe Respiratory Distress (Lung Complications)

• Extreme Difficulty Breathing – Large nitrogen bubbles can impair lung function, making oxygen absorption difficult.
• Cyanosis (Bluish Skin Tone) – A sign of oxygen deprivation, indicating dangerous respiratory or circulatory failure.

Who is at Risk for Decompression Sickness? 

DCS, can affect anyone exposed to rapid pressure changes.However, certain individuals face a higher risk due to their activities, work environments, or underlying health conditions. Identifying these high-risk groups is essential for prevention and early symptom recognition.

Scuba Divers & Free Divers

• Deep and Repetitive Diving – The deeper and longer a diver stays underwater, the more nitrogen dissolves into body tissues, increasing DCS risk upon ascent.
• Rapid Ascent & Ignoring Decompression Stops – Surfacing too quickly without following decompression protocols prevents nitrogen from safely exiting the body.
• Technical & Commercial Divers – Those using mixed gases or performing saturation dives are at an even greater risk due to prolonged exposure to high pressures.

Pilots & Astronauts

• Sudden Altitude Changes – Pilots flying at high altitudes without proper cabin pressurization can develop decompression sickness due to the rapid drop in atmospheric pressure.
• Astronauts in Space Missions – Spacewalks and pressure changes during launch or re-entry can cause DCS symptoms similar to those seen in divers.

Compressed Air Workers (Tunnel Workers, Miners & Engineers)

• Work in High-Pressure Environments – Jobs requiring work in pressurized tunnels, caissons, or underwater structures expose workers to pressure fluctuations that can lead to DCS if not managed correctly.
• Improper Decompression Procedures – Workers who exit a pressurized environment too quickly are at high risk of developing serious decompression-related injuries.

Individuals with Preexisting Health Conditions

• Lung & Respiratory Diseases – Conditions like chronic obstructive pulmonary disease (COPD) or asthma can impair nitrogen elimination, increasing DCS risk.
• Obesity – Excess body fat retains more nitrogen, making it harder for the body to offload dissolved gas safely.
• Dehydration & Poor Circulation – Lack of proper hydration reduces blood flow, slowing down nitrogen clearance from the body.
• Heart Defects (Patent Foramen Ovale – PFO) – Individuals with PFO (a small hole in the heart) are at a higher risk of nitrogen bubbles bypassing the lungs and entering arterial circulation, potentially causing stroke-like symptoms.

Diagnosis and Medical Treatment of Diver’s Disease

Decompression sickness (DCS), commonly known as “the bends,” is a serious condition that requires immediate medical evaluation and treatment. Proper diagnosis and timely intervention can prevent long-term complications and improve recovery outcomes.

How Decompression Sickness is Diagnosed?

1. Patient History & Symptom Evaluation

Doctors assess a patient’s recent diving history, altitude exposure, or work in high-pressure environments to identify potential risk factors. Symptoms such as joint pain, dizziness, neurological impairment, and breathing difficulties help guide the diagnosis.

2. Doppler Ultrasound (Bubble Detection Test)

A Doppler ultrasound is a non-invasive test that detects nitrogen gas bubbles circulating in the bloodstream. It is commonly used to monitor divers after a dive and confirm mild cases of decompression sickness.

3. MRI & CT Scans (Neurological Damage Assessment)

Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) scans help detect brain and spinal cord damage caused by decompression sickness. These imaging techniques are essential for diagnosing neurological DCS, which can result in long-term nerve damage if left untreated.

4. Blood Tests & Oxygen Level Analysis

Blood tests help assess oxygen saturation and identify potential clotting abnormalities related to gas bubble formation. These tests are also used to rule out other medical conditions that may mimic DCS symptoms, such as strokes or pulmonary embolisms.

Treatment for Decompression Sickness

1. Hyperbaric Oxygen Therapy (HBOT) – The Gold Standard Treatment

Hyperbaric oxygen therapy (HBOT) is widely recognized as a highly effective treatment for DCS, helping to restore normal oxygen levels in the body and alleviate symptoms. Patients are placed in a pressurized oxygen chamber where they breathe 100% oxygen at high pressure. This process helps shrink nitrogen bubbles, restores normal blood circulation, and promotes faster tissue healing.

2. Immediate Oxygen Therapy

In emergency situations, patients are given 100% pure oxygen through a mask or ventilator. Oxygen therapy accelerates the elimination of nitrogen from the body and prevents further complications before hyperbaric oxygen therapy can be administered.

3. IV Fluids & Supportive Care

Intravenous (IV) fluids are administered to prevent dehydration, which can worsen pressure sickness. Supportive care also includes monitoring heart rate, blood pressure, and neurological function to ensure the patient remains stable during treatment.

Key Takeaways: When to Seek Medical Help

DCS is a medical emergency, and immediate treatment is essential to prevent serious complications. Hyperbaric oxygen therapy remains the most effective solution, significantly improving recovery and reducing long-term risks. Early diagnosis through Doppler ultrasound, MRI, and CT scans plays a critical role in detecting severe or neurological complications before they become irreversible.

Preventing Decompression Illness: Essential Safety Tips for Divers

Decompression sickness can be prevented with proper dive planning, gradual ascents, and post-dive precautions. By following safe diving practices, divers can significantly reduce the risk of nitrogen bubble formation and the potential for serious medical complications.

Key Takeaways for DCS Prevention

• Ascend slowly and follow decompression stops to allow safe nitrogen release.
• Use a dive computer to track dive depth, time, and ascent speed.
• Stay hydrated and avoid alcohol or smoking to maintain proper blood circulation.
• Take surface intervals between dives to minimize nitrogen buildup.
• Wait minimum 12-24 hours after scuva diving before boarding flights.
• Recognize early symptoms of DCS and seek medical help immediately if needed.

FAQs About: The Bends

Final Thought On The Bends (DCS)

Decompression sickness is a serious but preventable condition affecting divers, pilots, and high-altitude travelers. By understanding how DCS affects the body, recognizing symptoms early, and following proper safety measures, individuals can reduce their risk. Hyperbaric oxygen therapy remains the most effective treatment, and prevention strategies such as controlled ascents, hydration, and dive planning are crucial for safe diving and aviation experiences.

This content is written by Dr. Arshi Thakur. If you found this content helpful, please consider sharing it on your social media to help others benefit from it!

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