Caisson’s disease

Jinu Janet Varghese

Parasseril Margrace David

Group:4

Year: 5

Definition• Also called Decompression sickness(DCS), also known as divers'

disease, the bends or caisson disease)

• Decompression sickness (DCS) occurs when the body is exposed to a sudden drop in surrounding pressure. DCS occurs most frequently during deep sea diving or when flying in a non-pressurized aircraft.

Causes• DCS is caused by the formation of gas bubbles in the blood and

tissues. At normal altitudes, nitrogen and other gases are exhaled or dissolved in the blood and tissues. However, during severe changes in altitude and air pressure, nitrogen and other gases form gas bubbles. These bubbles block the flow of blood. This condition can be fatal if not treated quickly.

• The air we breathe is mostly a mixture of two gases, nitrogen (78%) and oxygen (21%). Unlike oxygen, nitrogen is For this reason, most of the nitrogen we inhale is expelled when we exhale, but some is dissolved into the blood and other tissues. During a dive, however, the lungs take in more nitrogen than usual. This happens because the surrounding water pressure is greater than the air pressure at sea level (twice as great at 33 ft [10 m], for instance). As the water pressure increases, so does the pressure of the nitrogen in the compressed air inhaled by the diver. Because increased pressure causes an increase in gas density, the diver takes in more nitrogen with each breath than he or she would at sea level.

• Instead of being exhaled, however, the extra nitrogen safely dissolves into the tissues, where it remains until the diver begins his or her return to the surface (under some circumstances the extra nitrogen can cause nitrogen narcosis, but that condition is distinct from DCS). On the way up, decompression occurs (in other words, the water pressure drops), and with the change in pressure, the extra nitrogen gradually diffuses out of the tissues and is delivered by the bloodstream to the lungs, which expel it from the body. If the diver surfaces too quickly, however, potentially dangerous nitrogen bubbles can form in the tissues and cause DCS. These bubbles can compress nerves, obstruct arteries, veins, and lymphatic vessels, and trigger harmful chemical reactions in the blood.

Symptoms

• The less severe type of DCS is called DCS I. It primarily results in inflammation of muscles, joints, and tendons, resulting in pain and swelling. This is commonly referred to as the bends. Although pain may occur anywhere in the body, it is most common in or near an arm or leg joint. The pain may become more severe over time. Itching, skin mottling, weakness, and fatigue also occur.

• The more severe type of DCS is called DCS II. This results in more serious systemic effects, including neurological symptoms such as numbness and tingling. In the most severe form, numbness may lead to paralysis and even death. Other symptoms of DCS II include:

• Stomach pain

• Back pain

• Headache

• Dizziness

• Confusion

• Vision problems

• Vertigo

• Chest pain and severe coughing

• Shock

Frequency & Onset of DCS Symptoms

Symptoms Frequency

local joint pain 89%

arm symptoms 70%

leg symptoms 30%

dizziness 5.3%

paralysis 2.3%

shortness of breath 1.6%

extreme fatigue 1.3%

collapse/unconsciousness 0.5%

Time to onset Percentage of cases

within 1 hour 42%

within 3 hours 60%

within 8 hours 83%

within 24 hours 98%

within 48 hours 100%

Diagnosis

• Diagnosis requires taking a medical history and conducting a physical examination.

• The diagnosis is confirmed if the symptoms are relieved by recompression. Although MRI or CT can frequently identify bubbles in DCS, they are not as good at determining the diagnosis as a proper history of the event and description of the symptoms.

Treatment

• All cases of decompression sickness should be treated initially with 100% oxygen until hyperbaric oxygen therapy (100% oxygen delivered in a high-pressure chamber) can be provided. Mild cases of the "bends" and some skin symptoms may disappear during descent from high altitude

• It is beneficial to give fluids, as this helps reduce dehydration.

• The duration of recompression treatment depends on the severity of symptoms, the dive history, the type of recompression therapy used and the patient's response to the treatment.

Prognosis

• DCS sufferers who undergo chamber treatment within a few hours of symptom onset usually enjoy a full recovery.

• Immediate treatment with 100% oxygen, followed by recompression in a hyperbaric chamber, will in most cases result in no long term effects. However, permanent long-term injury from DCS is possible.

Prevention

• Limiting the depth and duration of deep sea dives

• Following standard diving guidelines

• Avoiding diving if you are obese, pregnant, have heart or lung problems, or have had a recent joint or limb injury

• Avoiding excessive alcohol consumption for 24 hours before diving

• Avoiding flying for 24 hours after deep sea diving

• Avoiding repeated dives within a 12-hour period

• Taking ibuprofen to help prevent altitude sickness when hiking

• Avoiding flights in nonpressurized aircraft