Decompression Sickness (The Bends): Symptoms, Types, and Emergency Actions

What are the symptoms of the bend?

The "bends," more formally known as Decompression Sickness (DCS), is a serious condition resulting from rapid pressure changes, typically during diving, where dissolved gases form bubbles in the body. Symptoms range from mild joint pain and skin irritations to severe neurological impairment, respiratory distress, and even death.

Understanding "The Bends" (Decompression Sickness)

Decompression Sickness (DCS) occurs when inert gases, primarily nitrogen, absorbed by the body's tissues under increased pressure (e.g., during a dive), come out of solution too rapidly during ascent. If the ascent is too fast or the decompression stops are insufficient, these gases form bubbles within the blood and tissues, leading to a variety of physiological effects. While most commonly associated with scuba diving, DCS can also affect astronauts, aviators in unpressurized aircraft, or workers in hyperbaric environments.

General Categories of Symptoms

The symptoms of DCS are highly variable and depend on the location and size of the gas bubbles. They can affect almost any body system, including the musculoskeletal system, skin, nervous system, and respiratory system. Symptoms are broadly categorized into Type I (less severe, often musculoskeletal or skin-related) and Type II (more severe, often neurological, pulmonary, or circulatory).

Common Symptoms of Decompression Sickness (Type I DCS)

These are generally considered less severe, though they still require medical attention.

• Joint Pain (The "Bends" Proper): This is the most classic symptom, giving the condition its common name. It typically manifests as a deep, aching pain, often in or around large joints like the shoulders, elbows, hips, and knees. The pain can range from mild to excruciating and is often described as a "dull ache" or "boring pain" that does not respond to movement or rest.
• Skin Manifestations:
  • Pruritus (Itching): Often described as an intense, crawling, or burning sensation, frequently in the torso and upper extremities.
  • Cutis Marmorata (Skin Mottling or Marbling): A distinctive patchy, red, or purplish rash that resembles a bruise or a map. It's caused by bubbles obstructing small blood vessels in the skin.
  • Edema (Swelling): Localized swelling, particularly around the affected joints or in areas of skin mottling.

Serious Symptoms of Decompression Sickness (Type II DCS)

These symptoms indicate more severe bubble formation and often involve vital organ systems, posing a significant threat to life or long-term health.

• Neurological Symptoms: These are the most dangerous and common Type II symptoms, resulting from bubbles affecting the brain, spinal cord, or peripheral nerves.
  • Brain Involvement: Severe headache, confusion, dizziness (vertigo), visual disturbances (blurred vision, double vision, tunnel vision), speech difficulties, altered mental status, seizures, or even unconsciousness.
  • Spinal Cord Involvement: Weakness or paralysis in limbs, numbness, tingling, "pins and needles" sensations, bladder or bowel dysfunction (difficulty urinating or defecating), and a band-like sensation around the torso. This is particularly common due to the spinal cord's rich blood supply and location.
  • Inner Ear (Vestibular) DCS ("Staggers"): Vertigo (spinning sensation), nausea, vomiting, nystagmus (involuntary eye movements), and hearing loss or ringing in the ears (tinnitus).
• Pulmonary Symptoms ("Chokes"): Occur when bubbles affect the lungs, leading to respiratory distress.
  • Chest Pain: A deep, burning pain under the sternum, often made worse by breathing.
  • Coughing: A persistent, dry, hacking cough.
  • Dyspnea (Shortness of Breath): Difficulty breathing, often described as gasping for air.
• Circulatory Symptoms (Shock): In severe, rare cases, widespread bubble formation can lead to cardiovascular collapse, characterized by low blood pressure, rapid pulse, and loss of consciousness.

Factors Influencing Symptom Presentation

The specific symptoms and their severity can be influenced by several factors:

• Dive Profile: Depth, bottom time, and the rate of ascent are critical. Deeper, longer dives with rapid ascents increase risk.
• Individual Physiology: Factors like age, body composition (fat content), hydration status, and pre-existing medical conditions can affect susceptibility.
• Post-Dive Activities: Strenuous exercise, hot showers, or flying too soon after a dive can exacerbate bubble formation or movement.
• Gas Mixtures: Diving with specialized gas mixtures (e.g., nitrox, trimix) alters the decompression requirements and potential symptom profiles.

When Do Symptoms Appear?

The onset of DCS symptoms can vary significantly:

• Immediate: Some symptoms may appear immediately upon surfacing.
• Within Minutes to Hours: The vast majority (85-90%) of DCS cases manifest within the first hour after surfacing.
• Delayed Onset: In rare cases, symptoms can be delayed up to 24 hours or even longer, particularly for milder forms or if other factors like flying after diving are involved.

Immediate Action: What To Do If You Suspect The Bends

DCS is a medical emergency. Prompt action is crucial to minimize long-term damage or fatality.

• Seek Immediate Medical Attention: Contact emergency services (e.g., 911 or local equivalent) or a specialized dive emergency hotline.
• Administer 100% Oxygen: If available and the person is conscious and breathing, administer 100% oxygen via a non-rebreather mask. This helps flush nitrogen from the body and shrink existing bubbles.
• Lie Flat: Position the person lying flat, preferably on their back.
• Hydration: If conscious and able to swallow, encourage sips of water.
• Prepare for Transport: The definitive treatment for DCS is recompression in a hyperbaric chamber, which requires specialized medical transport.

Prevention Is Key

Understanding the symptoms is vital, but prevention is paramount. Adherence to safe diving practices, including conservative dive profiles, slow ascents, adequate safety stops, and avoiding strenuous activity or flying too soon after a dive, significantly reduces the risk of Decompression Sickness. Always dive within your training and experience limits.