Scuba Diving: Barotrauma and Decompression Sickness

Barotrauma/Decompression Sickness Overview

Barotrauma refers to medical problems that arise from the pressure differences between areas of the body and the environment and is a particular concern for scuba divers.

Certain laws of physics apply to this topic. Boyle's law states that the product of the multiplication of pressure and volume remains a constant. As the pressure increases, the volume decreases and vice versa. As you dive deeper when scuba diving, pressure increases and this volume change in gas-filled spaces and organs within your body accounts for the distortion and damage to surrounding tissues.

  • Decompression sickness, or "the bends," is related more to Henry's Law, which states that more gas will be dissolved in a liquid when the gas is pressurized. Because of the water pressure, body tissue absorbs nitrogen gas faster as a diver descends than when ascending to the surface. However, if a diver ascends too quickly, nitrogen gas bubbles will form in body tissue rather than being exhaled. The nitrogen bubbles cause severe pain.
  • External ear squeeze occurs when your ear canal is blocked by something such as earplugs or earwax. As the water pressure increases while you descend, the air pocket between the obstruction and the tympanic membrane (eardrum) shrinks. This can damage the tissue in the ear canal, usually your eardrum.
  • Middle ear squeeze occurs when you cannot equalize the pressure in your middle ear. The eustachian tube is a small canal that connects the middle ear to the back part of the nasal cavities and allows pressure to equalize. When there is a problem with the tube, the middle ear volume decreases and pulls the eardrum inward, creating damage and pain. You can try certain maneuvers, called Valsalva maneuvers, such as yawning or trying to blow with your nose and mouth closed, to open the tube and equalize the pressure.
  • Inner ear barotrauma occurs from the sudden development of pressure differences between the middle and inner ear. This can result from an overly forceful Valsalva maneuver or a very rapid descent. The result is usually ringing in the ear, dizziness, and deafness. This injury is less common than a middle ear squeeze.
  • Less common types of barotrauma include the following. All involve air trapped in an enclosed area where pressure cannot equalize during descent causing a vacuum effect where it occurs.
    • Sinus squeeze: When air becomes trapped in the sinuses because of congestion or cold symptoms, a sinus squeeze can occur.
    • Face mask squeeze: This occurs if you do not exhale through your nose into the dive mask while descending (equalizing).
    • Suit squeeze: A dry diving suit tightly encloses an area of skin.
    • Lung squeeze: This occurs when you are free-diving, but very few divers can hold their breath to depths that cause this injury to occur.
    • Tooth squeeze: This occurs during an ascent while scuba diving and air becomes trapped in a filling or cavity.
    • Gastric squeeze (aerogastralgia): This occurs when gas swallowed during diving expands during ascent. This happens more often with novice divers and causes temporary pain but rarely significant damage.
  • Barotrauma can occur during ascent also. A reverse squeeze occurs in the middle ear or sinus when a diver has an upper respiratory infection (cold) and has used nasal spray to open the breathing passages. As the spray wears off during diving, tissues swell and cause obstruction, resulting in a pressure difference and damage. During "bounce diving" the eustachian tube may become inflamed and lead to a middle ear squeeze.
  • Pulmonary barotrauma (pulmonary overpressurization syndrome, POPS, or burst lung) can occur if the diver fails to expel air from the lungs during ascent. As the diver rises, the volume of the gas in the lung expands and can cause damage if the excess is not exhaled.
  • Air embolism is the most serious and most feared consequence of diving.
    • While scuba diving, gas bubbles can enter the circulatory system through small ruptured veins in the lungs.
    • These bubbles expand during ascent, following Boyle's Law, and can pass through the heart to obstruct blood flow in the arteries of the brain or heart.
      • This most commonly occurs when a diver ascends rapidly because of air shortage or panic.
      • The diver then passes out, experiences a stroke, or has other nervous system complaints within minutes of surfacing.
      • The brain is affected more than other organs because gas rises, and most divers are in a vertical position while ascending.
  • Decompression sickness (DCS, "the bends") involves gases diffusing into the tissues and getting trapped there. The diver now has gas bubbles in places where there should be none. Nitrogen is the usual culprit.
    • During descent and while on the bottom, the diver absorbs nitrogen into the tissues until they reach a pressure balance.
    • When the diver ascends at the right rate, the gas diffuses from the tissues. However, if the diver ascends too rapidly to allow diffusion, the nitrogen bubbles will expand in the tissues as pressure decreases.
    • Different body parts can be affected, depending on where the bubbles are located.

Barotrauma/Decompression Sickness Causes

Two different phenomena cause barotrauma:

  • The inability to equalize pressures
  • The effect of pressure on an enclosed volume
  • Decompression sickness is caused by the elevated pressures of the gas mixture inhaled underwater that diffuse into the body tissues, and then the inadequate diffusion of the gas from the tissues if the diver surfaces too quickly.
  • Middle ear squeezes occur because of obstruction of the Eustachian tube.
    • The most common cause is an upper respiratory infection (cold), creating congestion.
    • Other causes of obstruction include congestion caused by allergies or smoking, mucosal polyps, excessively aggressive Valsalva attempts, or previous facial injuries.
  • Factors that trigger sinus squeezes include a cold, sinusitis, or nasal polyps.
  • Contributing factors to aerogastralgia (swallowing air) include performing Valsalva maneuvers with the head down (which allows air swallowing), consuming carbonated beverages or heavy meals prior to diving, or chewing gum while diving.
  • Pulmonary barotrauma occurs from the diver holding their breath during ascent, which allows pressure to rise in the lungs.
    • The pressure increase results in rupture.
    • Air also may penetrate into the tissue around the lungs.
  • The classic description of a dive causing an air embolism is rapidly ascending to the surface because of panic.
  • Failure to make recommended decompression stops during ascent usually causes decompression sickness. Stops are based on diving tables or charts, which factor into account the depth, duration of the dive, and previous dives completed and give you guidelines on the proper rate of ascent.

Barotrauma/Decompression Sickness Symptoms

You should consider the signs and symptoms of diving injuries with regard to your overall dive plan, including what part of the dive you were performing when the problems occurred.

  • The history of the dive is very important to medical personnel and should always be included when assistance is required.
    • Barotrauma such as squeezes will commonly occur during descent, and the symptoms will frequently prevent a diver from reaching the desired depth.
    • You will notice symptoms of aerogastralgia, pulmonary barotrauma, air embolism, and decompression sickness both during and after ascent.

The following are symptoms for specific pressure problems:

  • External ear squeeze: Pain in your ear canal and blood from your ear
  • Middle ear squeeze: Ear fullness, pain, eardrum rupture, disorientation, nausea, and vomiting
  • Inner ear barotrauma: Feeling that your ear is full, nausea, vomiting, ringing in the ear, dizziness, and hearing loss
  • Sinus squeeze: Sinus pressure, pain, or nasal bleeding
  • Face mask squeeze: "Bloodshot" eyes and redness or bruising of the face under the mask
  • Lung squeeze: Chest pain, cough, bloody cough, and shortness of breath
  • Aerogastralgia (gastric squeeze): Abdominal fullness, colicky pain (severe pain with fluctuating severity), belching, and flatulence (gas expelled through the anus).
  • Pulmonary barotrauma: Hoarseness, neck fullness, and chest pain several hours after diving. Shortness of breath, painful swallowing, and loss of consciousness also may occur.
  • Air embolism: Sudden loss of consciousness within 10 minutes of surfacing. Other symptoms include paralysis, numbness, blindness, deafness, dizziness, seizures, confusion, or difficulty speaking. The paralysis and numbness can involve several different parts of the body at the same time.
  • Decompression sickness: Rashes, itching, or bubbles under your skin
    • Lymphatic obstruction which can cause localized swelling
    • Musculoskeletal symptoms include joint pain that worsens with movement and commonly involves the elbows and shoulders
    • Nervous system after-effects include paralysis, sensory disturbances, and bladder problems, usually the inability to urinate.
    • Pulmonary symptoms include chest pain, cough, and shortness of breath.
    • Symptoms usually appear within 1 hour of surfacing but can be delayed up to 6 hours. In rare instances symptoms may not appear until 48 hours after the dive.
    • Flying in a commercial aircraft after diving may cause "the bends" to develop in the airplane because the cabin pressure is less than sea level pressure.

When to Seek Medical Care

Most problems that arise from barotrauma will require medical diagnosis or treatment. The most important thing the patient can do if they experience barotrauma is to seek medical attention and avoid future dives until cleared by a doctor.

Some injuries from barotrauma require immediate medical attention, while others can wait for treatment. In all cases, stop further diving until the patient has been seen by a doctor.

Air embolism is life threatening and requires immediate attention. Planning ahead is important.

  • Know the location of the nearest emergency facility and recompression (hyperbaric) chamber before you dive.
  • Bring emergency phone numbers with you on the dive. A phone can be the best immediate life saving tool.
  • The Divers Alert Network (DAN) at Duke University maintains a list of recompression facilities and can be reached around the clock at (call local EMS first, then DAN):
    • (919) 684-8111 (collect)
    • 800-446-2671 (toll free)
    • 1-919-684-9111 (Latin America Hotline)
  • If a diver collapses within 10 minutes of diving, suspect air embolism and seek help immediately. Most U.S. communities have an emergency access number (911). Find out in advance if such a number is available and how to activate emergency medical services when diving in a foreign country. A diver who has collapsed requires oxygen and emergency life support. Lay the person flat and keep the diver warm until help arrives.

Decompression sickness also requires immediate attention, but its symptoms may not appear as quickly as those of air embolism.

  • Information on recompression chambers is important and generally can be obtained through the emergency medical system (911 in the U.S.).
  • Divers with complaints consistent with decompression sickness should seek attention through their doctor or a hospital's emergency department.

Pulmonary barotrauma and lung squeeze will require attention in an emergency department in most instances because the studies required to evaluate the symptoms and determine the possible treatment must be performed in the hospital environment.

A doctor can evaluate and treat ear squeezes and sinus squeezes initially and refer the patient to a specialist if required.

  • Evaluation may require a dive history.
  • Ear squeezes require an examination to ensure the eardrum has not ruptured.

The diver needs immediate medical attention if they lose consciousness, show paralysis, or exhibit stroke symptoms within 10 minutes of surfacing.

You or your diving buddy should contact an ambulance through 911 or the local emergency phone numbers.

Symptoms of chest pain and shortness of breath may occur minutes to hours after a dive. These require emergency department evaluation.

  • If the symptoms are severe enough, contact an ambulance. Otherwise, have someone drive the patient to the hospital, but do not drive yourself.
  • These symptoms can be dive-related or could be caused by another condition, such as a heart attack. This will be sorted out in the hospital.

Decompression sickness, or "the bends,” may require an emergency department to control pain and arrange for recompression services using specialized equipment that is available only at regional centers that specialize in barotrauma.

Dizziness or pain from a squeeze may require emergency attention as well. When in doubt, contact a doctor or a local emergency department for advice.

Exams and Tests

The doctor will gather information about the dive and perform a standard physical exam, paying particular attention to the areas of pain and nervous system.

Depending on the patient's condition, they may be referred immediately to a recompression (hyperbaric) chamber or may undergo further testing.

  • The patient's vital signs will be taken, measuring blood pressure, pulse, breathing rate, and temperature.
  • Doctors will do a pulse oximetry - an instrument that measures the level of oxygen in the blood - using a sensor on a finger or earlobe.
  • The most common initial treatments may be oxygen (through a face mask or a tube near the nose) and intravenous fluids.

Air embolism and decompression sickness usually will require recompression treatment and repeated physical examinations. After treatment, the doctor may recommend a specialized imaging study (CT scan or MRI) to further evaluate any neurological problems.

Chest pain and shortness of breath associated with pulmonary barotrauma may require an electrocardiogram (ECG) and a chest X-ray.

The doctor will inspect the patient's ear canal and eardrum if they have an ear squeeze, looking for physical signs that can range from no visible problems to a small amount of bleeding to eardrum rupture to heavy bleeding.

Any hearing loss or dizziness will probably require referral to an otolaryngologist (ear, nose, and throat specialist) or audiologist (hearing specialist). They will test the patient's hearing and balance systems to determine if they have suffered any inner ear problems.

Barotrauma/Decompression Sickness Treatment

The most serious diving complications - air embolism and decompression sickness - will require recompression therapy in a hyperbaric chamber. These hyperbaric chambers may be freestanding or associated with a local hospital. The chamber itself is typically made of thick metal plates with windows for observation. On the outside there are many pipes and valves. The chamber is usually large enough to accommodate more than one person. Medical personnel may come into the chamber with the patient or stay outside, watch through the window, and communicate by intercom, depending on the severity of the illness. While inside the chamber, one may experience loud noises or cold as the pressures change. Similar to diving, one will need to do Valsalva maneuvers to clear the ears while being pressurized. The patient will be closely monitored and be given specific instructions while they are in the chamber.

Other injuries can be managed at the hospital or doctor's office. All conditions will require avoidance of diving until improved.

  • The patient may need to be transported to another location for hyperbaric treatments. This may include low-level flights in an aircraft to minimize further pressure changes.
  • "Treatment tables" will determine the length of treatment and treatment steps. These tables take into account the depth, time of dive, decompression stops, and previous dives performed. The hyperbaric specialist will recommend which table to use.
  • The hyperbaric chamber will increase the air pressure to make any gas bubbles inside the tissues smaller and to allow them to go away properly to avoid injury.

Pulmonary barotrauma may result in a collapsed lung (pneumothorax). If this occurs, the doctor must first determine how much of the lung has collapsed. If the collapse is relatively small the patient can be treated with supplemental oxygen and observation. Larger ones require that air be withdrawn from the body.

  • Depending on the amount of air in the cavity, the doctor could use a needle or a hollow tube to withdraw air from the cavity.
  • The needle will withdraw small amounts of air, and then the patient will be observed for at least 6 hours.
  • Larger collapses require a catheter, or chest tube, to be placed in the chest wall and remain for a few days until the lung that has been damaged can heal.
  • Doctors must insert this tube through the skin into the chest cavity by doing a small surgical procedure. Local anesthetics reduce and generally eliminate any pain associated with this procedure.
  • The tube is attached to a flutter valve or suction to promote air escape from the inappropriate space.

Self-Care at Home

There is no special treatment for face mask and suit squeezes. They usually go away in a few days.

Aerogastralgia symptoms usually clear up on their own and do not require attention unless the abdominal discomfort continues to worsen and does not go away in a few hours.

Pain from ear or sinus squeezes can be treated with over-the-counter pain relievers, such as acetaminophen (Tylenol), ibuprofen (Motrin, Advil), or naproxen (Aleve). The patient should visit a doctor to exclude possible serious ear injuries.

Medications

Sinus squeezes usually require oral and nasal decongestants. Antibiotics are usually recommended for a squeeze involving the frontal sinuses. Pain medication may also be prescribed.

Ear squeezes also require decongestants, both oral and long-acting nasal types. Antibiotics may be given if the patient had a rupture, a previous infection, or the diving occurred in polluted waters. Pain medication also may be prescribed.

Follow-up

Doctors will recommend follow-up based on the diagnosis.

Make sure everything has healed and the patient has received clearance before diving again.

Prevention

The best prevention against barotrauma is to plan and prepare for your dive properly.

  • Make sure you are in good health with no upper respiratory or sinus problems.
  • Obtain the proper training and always use the buddy system (never dive alone).
  • Check that your equipment is in good working order.
  • Know the local emergency phone numbers in advance and have a means of contacting help, for instance, with a cellular phone. (The location of the nearest recompression facility could be very important in a problem such as air embolism.)
  • Newer "dive computers" designed to maximize safety can be used and may allow longer diving times and fewer or shorter decompression stops. They provide information similar to the original diving tables but are more precise. Be certain you are familiar with their use before depending on them.
  • Avoid flying in a plane within 24 hours of diving to reduce the risk of "the bends" occurring unexpectedly in the lower air pressure of an airplane cabin.

Outlook

Most people recover from their diving accidents and are able to participate in future dives.

  • Air embolism can be the most devastating complication from a diving accident. The initial problems that occur can be very dramatic. Appropriate measures, including recompression, must be taken quickly to minimize disabilities. Recovery rates for people reaching a recompression chamber have been high.
  • Decompression sickness can also generally be treated effectively and result in very good recovery rates when recompression is performed, even several days after the initial onset.
  • Pulmonary barotrauma associated with a collapsed lung (pneumothorax) may require several days in the hospital if a chest tube is placed. There is always a risk of recurrence once a diver has a collapsed lung. Complete recovery will usually take several weeks to months.
  • Mild ear squeezes usually take about 1-2 weeks to recover. More significant ones, typically associated with eardrum rupture, may take longer. Depending on the severity and amount of damage, surgery may be recommended.
Reviewed on 11/17/2017

Medically reviewed by Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care

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