Decompression sickness

Decompression sickness

Description of decompression sickness

The vessel is a device for working at a depth below the water surface. It has the shape of a bell, in which the workers and air and outside bell water pressure acting on the bell. For these people it was first observed and described decompression sickness, and was named by the device Decompression illness.

Of decompression sickness is caused by a sudden change in pressure of gas dissolved in tissues.Typically occurs when scuba diving and subsequent rapid emergence.

When diving depth is in the tissues for the relative pressure of dissolved a certain amount of gas (the most important gas due to problems caused by nitrogen). A process that is in fact happening is called carbonation tissue. The gas supply to the tissue is dependent on the blood flow, the highest gas dissolves in the tissues with the greatest blood supply (brain, organs). The opposite process occurs during ascent, occurs offgassing tissue. The air in the lungs is getting gas from tissues when in them in larger amounts than is the ambient pressure. The surplus is vydýcháván. The problem occurs when it is too rapid emergence. A rapid decrease in ambient pressure in the tissues is suddenly a large amount of surplus gas, which can not be fast enough to divert blood to the lungs and breathe. The individual gases in this completely different properties. The excess oxygen is immediately absorbed and used tissues. Problematic is nitrogen, which does not use tissues and you can not get rid of him suddenly.
In tissues and blood vessels are formed bubbles excess gas. These can clog blood vessels and leads to embolism. On the surface of the bubbles also leads to blood clotting (thrombus formation) and can lead to subsequent thrombosis. When blood clotting also leads to vasoconstriction (shrinkage of blood vessels, further blood vessel closes and the bubble is firmly retained. The stubborn tissues such as bone, there is the action of bubbles to mechanical oppression nourishing blood vessels and soon leads to hypoxia (lack of oxygen). Pliable tissue can hmožděny action to be bubbles or tearing.
Bubbles are almost always composed of nitrogen or helium according to the composition of the mixture of breathing gas.

Bubble formation and damage to the body is gradual, so symptoms after decompression may occur after a few minutes or, conversely, even after hours.

The prognosis is through advanced recompression therapy for early treatment is very good. Without treatment, life-threatening condition.

Risk factors for decompression sickness

Bends induces labor in the caisson (high pressure), under which got its name, with subsequent discharge into the environment above the level of normal (normal pressure). Today it can be exceptionally on the experience with a similar problem with the workers of the mines (sometimes in a mine intentionally causes overpressure in solving the problem with ground water).
Most often it occurs decompression sickness in divers. Causes of disease in which divers can occur a few. Diver emerges too quickly and does not respect the rule mandatory stops by decompression tables (tables prepared for a safe ascent with prescribed breaks, including their duration, with respect to the maximum depth, dive time, depth and activity in certain other characteristics). The second most common reason is that it is under water for too long. Tissue saturation gases is proportional not only to the depth (and thus the ambient pressure), but also the time spent in the increased pressure. Also not emerge breath-hold, as it will otherwise formed overpressure in the lungs and air enters under pressure into the bloodstream. Also affect divers who in a very short time after surfacing flying aircraft (the pressure at altitude, although in a plane corrected, but it is lower than at sea level).

Decompression sickness is not only divers. It can also occur when traveling airliner, the abrupt failure correction pressure and the resulting vacuum. Also set for aircraft without pressure correction (pressurized cabin) with a steep climb up. The disease is then called desaturation aeropatie.

For easier formation of bubbles at a decompression sickness it is also known several general risk factors. Gases such as nitrogen is readily soluble in fats. Therefore at risk of having obese people. Also, vulnerable women, who have in the body of the same weight as a man physiologically more fat. Another factor is age (with older age facilitate the formation of bubbles). Equally important is the labor intensity during the dive (with increasing difficulty increases blood circulation and the higher-gassing).

Prevention of decompression sickness

Prevention of decompression sickness is careful planning and adherence to schedule diving. It is important to observe the scheduled time at certain depths, not to exceed a tolerable time ongassing. When the output of two possible procedures. The first is the so-called compliance. Zero times. According to the tables may be in compliance with given periods of residence in the respective depths ascend constant rate of about 10 m / sec without stopping. If it is exceeded zero time is appropriate to use the second method and observance of decompression stops.Decompression stops are pauses in which the diver remains at a certain level of pressure. After a certain time according to a decompression table during which saturation decreases tissue gas continues to the next lower level of the pressure, which again makes decompression stop. In this procedure minimizes the risk of a sudden drop in ambient pressure and therefore the bubble formation.
All documents for planning include diving decompression tables. There’s account of the duration, depth, activity in depth correction times and depths for repetitive diving and other characteristics.For safer diving it is more convenient to use for planning and control of the diving computer.

The symptoms of decompression sickness

Depending on the seriousness divided Decompression disease type 1 with a milder course and type 2 with severe course and an increased risk of complications. Most often affected organs with the highest blood flow (digestive tract, heart, lungs)

In milder forms of pain leads to major joints (shoulder, elbow, knee, hip). The skin rash appears. It violated sensitivity (parestézie- tingling, numbness).

For more severe form leads to abdominal pain, loss of appetite, chest pain, dyspnea, cough, heart failure, headaches and other neurological symptoms, according to the affected structures in the brain. Emboli to the brain causes according to the severity of dizziness, convulsions and loss of consciousness. May be present impaired vision, speech, hearing, general disorientation, impaired mobility (paresis-reduced momentum until kvadruplegie- inability to move all extremities). It may also happen thrombosis (local myocardial tissue of varying scope).

Decompression sickness is often accompanied by damage to the ear (hearing). According to the state of the eardrum leads to its rupture (when most damage eardrum otitis media is sufficient to rupture the eardrum even slight pressure increase at a small depth) damage is not due to an increase in pressure before decompression sickness.

Treatment of Decompression Sickness

The treatment is recompression therapy pressure (hyperbaric) chamber. The patient is quickly placed in a pressure (rapid decompression, bubbles reduces until disappearing) and then the pressure is gradually reduced (slow decompression). Furthermore, the patient breathing mask 100% oxygen. Collectively method is called hyperbaric oxygen therapy. They must be implemented as soon as possible, before they develop complications of decompression sickness. If necessary, supplemented with anti-shock therapy and symptomatic treatment of symptoms.

Complications of decompression sickness

The most serious complication is lung damage and the effects of air embolism. Both are serious, life-threatening conditions. Serious lung damage manifests as ARDS (acute respiratory distress syndrome, acute respiratory distress syndrome), usually accompanied by pneumothorax. Air embolism causes most hypoxic (oxygen deprivation) damage to the central nervous system (CNS, brain and spinal cord).

CNS involvement may have permanent neurological sequelae (memory disorders, sensory disturbances, movement disorders, cognitive impairment).

Permanent damage can also be lung (reduction in vital capacity), joints and bones (aseptic osteonecrosis bone).

Other names: decompression sickness, decompression sickness, desaturation aeropatie

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