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Encyclopedia > Decompression sickness
Caisson disease [decompression sickness]
Classification & external resources
ICD-10 T70.3
ICD-9 993.3
DiseasesDB 3491
eMedicine emerg/121 
MeSH C21.866.120.248

Decompression sickness (DCS), the diver’s disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a decrease (nearly always after a big increase) in the pressure around his body. It is a type of diving hazard and dysbarism. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) is a coding of diseases and signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or diseases, as classified by the World Health Organization (WHO). ... // S00-T98 - Injury, poisoning and certain other consequences of external causes (S00-S09) Injuries to the head (S00) Superficial injury of head (S01) Open wound of head (S02) Fracture of skull and facial bones (S03) Dislocation, sprain and strain of joints and ligaments of head (S04) Injury of cranial nerves... The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... This article is about pressure in the physical sciences. ... Divers face specific physical and health risks when they go underwater (e. ... Dysbarism refers to medical conditions resulting from changes in ambient pressure. ...

Contents

Introduction

Decompression sickness can happen in these situations:

  • A diver ascends quickly from a dive or does not carry out decompression stops after a long or deep dive.
  • An unpressurized aircraft flies upwards.
  • The cabin pressurization system of an aircraft fails.
  • Divers flying in any aircraft shortly after diving. Pressurized aircraft are not risk-free since the cabin pressure is not maintained at sea-level pressure. Commercial aircraft cabin pressure is often set to the pressure of about 8,000 feet above sea level.
  • A worker comes out of a pressurized caisson or out of a mine, which has been pressurized to keep water out.
  • An astronaut exits a space vehicle to perform a space-walk or extra-vehicular activity where the pressure in his spacesuit is lower than the pressure in the vehicle.
This surfacing diver must enter a recompression chamber to avoid the bends.

These situations cause inert gases, generally nitrogen, which are normally dissolved in body fluids and tissues, to come out of physical solution (i.e., outgas) and form gas bubbles. A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ... Flying machine redirects here. ... Cabin pressurization is the active pumping of air into the cabin of an aircraft to increase the air pressure within the cabin. ... In engineering, a caisson is a retaining, watertight structure used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, or for the repair of ships. ... Chuquicamata, the second largest open pit copper mine in the world, Chile. ... Astronaut Bruce McCandless II using a manned maneuvering unit outside the U.S. Space Shuttle Challenger in 1984. ... Astronaut Bruce McCandless on an untethered EVA Extra-vehicular activity (EVA) is work done by an astronaut away from the Earth and outside of his or her spacecraft. ... Apollo 15 space suit A spacesuit is a complex system of garments, equipment, and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space. ... Download high resolution version (550x839, 41 KB)Captain Chris Murray, Supervisor of Diving at Naval Sea Systems Command in Norfolk, VA, takes his MK-21 Dive Helmet off after completing the in-water phase of his dive. ... Download high resolution version (550x839, 41 KB)Captain Chris Murray, Supervisor of Diving at Naval Sea Systems Command in Norfolk, VA, takes his MK-21 Dive Helmet off after completing the in-water phase of his dive. ... A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Making a saline water solution by dissolving table salt (NaCl) in water This article is about chemical solutions. ... Look up bubble in Wiktionary, the free dictionary. ...


According to Henry’s Law, when the pressure of a gas over a liquid is decreased, the amount of gas dissolved in that liquid will also decrease. One of the best practical demonstrations of this law is offered by opening a soft drink can or bottle. When you remove the cap from the bottle, you can clearly hear gas escaping and see bubbles forming in the soda. This is carbon dioxide gas coming out of solution as a result of the pressure inside the container reducing to atmospheric pressure. In chemistry, Henrys law is one of the gas laws, formulated by William Henry. ... This article is about pressure in the physical sciences. ... Gas can also refer to gasoline and natural gas and also hydrogen. ... For other uses, see Liquid (disambiguation). ... A soft drink is a drink that contains no alcohol. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ...


Similarly, nitrogen is an inert gas normally stored throughout the human body, such as tissues and fluids, in physical solution. When the body is exposed to decreased pressures, such as when flying an un-pressurized aircraft to altitude or during a scuba ascent through water, the nitrogen dissolved in the body outgases. If nitrogen is forced to come out of solution too quickly, bubbles form in parts of the body causing the signs and symptoms of the "bends" which can be itching skin and rashes, joint pain, sensory system failure, paralysis, and death. Making a saline water solution by dissolving table salt (NaCl) in water This article is about chemical solutions. ... Scuba diving is swimming underwater while using self-contained breathing equipment. ... The term symptom (from the Greek meaning chance, mishap or casualty, itself derived from συμπιπτω meaning to fall upon or to happen to) has two similar meanings in the context of physical and mental health: Strictly, a symptom is a sensation or change in health function experienced by a patient. ... A rash is a change in skin which affects its color, appearance, or texture. ... For other uses, see Joint (disambiguation). ... This article or section may be confusing for some readers, and should be edited to be clearer or more simplified. ... Paralysed redirects here. ... For other uses, see Death (disambiguation), Dead (disambiguation), Death (band) or Deceased (band). ...


An air embolism, caused by other processes, can have many of the same symptoms as DCS. The two conditions are grouped together under the name decompression illness or DCI. An air embolism, or more WITCH generally gas embolism, is a medical condition caused by gas bubbles in the bloodstream (embolism in a medical context refers to any large moving mass or defect in the blood stream). ... This article needs cleanup. ...


History

Wikisource has the text of the 1911 Encyclopædia Britannica article Caisson Disease.
  • 1841: First documented case of decompression sickness, reported by a mining engineer who observed pain and muscle cramps among coal miners working in mine shafts air-pressurized to keep water out.
  • 1867: The submarine pioneer Julius H. Kroehl died of decompression sickness during experimental dives with the Sub Marine Explorer.
  • 1869: An early case resulting from diving activities while wearing an air-pumped helmet.
  • 1872: Washington Roebling suffered from caisson disease while working as the chief engineer on the Brooklyn Bridge. (He took charge after his father John Augustus Roebling died of tetanus.) Washington's wife Emily helped manage the construction of the bridge, after his sickness confined him to his home in Brooklyn. He battled the after-effects of the disease for the rest of his life.
  • 1880: Decompression sickness became known as "The Bends" because afflicted individuals characteristically arched their backs in a manner reminiscent of a then popular women's fashion called the Grecian Bend.

Image File history File links Wikisource-logo. ... The original Wikisource logo. ... Encyclopædia Britannica, the eleventh edition The Encyclopædia Britannica Eleventh Edition (1910–1911) is perhaps the most famous edition of the Encyclopædia Britannica. ... Wyoming coal mine Coal mining is the mining of coal. ... Shaft mining is a type of underground mining done by use of a mine shaft. ... Julius Herman Kröhl (in English his name is written Kroehl) was an American inventor of German descent. ... The Sub Marine Explorer was a submarine built in 1865 by Julius H. Kroehl in New York for the Pacific Pearl Company. ... The standard diving dress was used from its invention in 1837 until replaced by the rise of SCUBA and other modern diving outfits in the 1960s. ... Washington Augustus Roebling (May 26, 1837 – July 21, 1926) was an American civil engineer best known for his work on the Brooklyn Bridge, which was initially designed by his father John A. Roebling. ... For other uses, see Brooklyn Bridge (disambiguation). ... Categories: Stub | 1806 births | 1869 deaths | Engineers ... Tetanus is a medical condition that is characterized by a prolonged contraction of skeletal muscle fibers. ... This article is about the borough of New York City. ... The Grecian Bend was a dance move introduced to polite society in America just before the Civil War. ...

Predisposing factors

  • Magnitude of the pressure reduction: A large pressure reduction is more likely to cause DCS than a small one. For example, the ambient pressure halves by ascending during a dive from 10 metres / 33 feet (2 bar) to the surface (1 bar), or by flying from sea level (1 bar) to an altitude of 16,000 feet / 5,000 metres (0.5 bar) in an un-pressurized aircraft. Diving and then flying shortly afterwards increases the pressure reduction as does diving at high altitude.
  • Repetitive exposures: Repetitive dives or ascents to altitudes above 18,000 feet within a short period of time (a few hours) also increase the risk of developing altitude DCS.
  • Rate of ascent: The faster the ascent, the greater the risk of developing altitude DCS. An individual exposed to a rapid decompression (high rate of ascent) above 18,000 feet has a greater risk of altitude DCS than being exposed to the same altitude but at a lower rate of ascent.
  • Time at altitude: The longer the duration of the flight to altitudes of 18,000 feet and above, the greater the risk of altitude DCS.
  • Age: There are some reports indicating a higher risk of altitude DCS with increasing age.
  • Previous injury: There is some indication that recent joint or limb injuries may predispose individuals to developing "the bends."
  • Ambient temperature: There is some evidence suggesting that individual exposure to very cold ambient temperatures may increase the risk of altitude DCS.
  • Body Type: Typically, a person who has a high body fat content is at greater risk of altitude DCS. Due to poor blood supply, nitrogen is stored in greater amounts in fat tissues. Although fat represents only 15 percent of a normal adult body, it stores over half of the total amount of nitrogen (about 1 litre) normally dissolved in the body.
  • Exercise: When a person is physically active, or performing strenuous activity before or after a dive (such as rowing to and from a dive site), there is greater risk of DCS.
  • Alcohol consumption/dehydration: While conventional wisdom would have one believe that the after effects of alcohol consumption increase the susceptibility to DCS through increased dehydration, one study concluded that alcohol consumption did not increase the risk of DCS.[1]. The high surface tension of water is generally regarded as helpful in controlling bubble size, hence avoiding dehydration is recommended by most experts.
  • Patent foramen ovale: A hole between the atrial chambers of the heart in the fetus is normally closed by a flap with the first breaths at birth. In up to 20 percent of adults the flap does not seal, however, allowing blood through the hole with coughing or other activities which raise chest pressure. In diving, this can allow blood with microbubbles in the venous blood from the body to return directly to the arteries (including arteries to the brain, spinal cord and heart) rather than pass through the lungs, where the bubbles would otherwise be filtered out by the lung capillary system. In the arterial system, bubbles (arterial gas embolism) are far more dangerous because they block circulation and cause infarction (tissue death, due to local loss of blood flow). In the brain, infarction results in stroke, in the spinal cord it may result in paralysis, and in the heart it results in myocardial infarction (heart attack).

This article does not cite any references or sources. ... An atrial septal defect (ASD) is a group of congenital heart diseases that involve the inter-atrial septum of the heart. ... The heart and lungs, from an older edition of Grays Anatomy. ... Description An air embolism, or more generally gas embolism, is a medical condition caused by gas bubbles in the bloodstream. ... This article does not adequately cite its references or sources. ... For other uses, see Stroke (disambiguation). ... Paralysed redirects here. ... Acute myocardial infarction (AMI or MI), more commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ... Acute myocardial infarction (AMI or MI), more commonly known as a heart attack, is a disease state that occurs when the blood supply to a part of the heart is interrupted. ...

Signs and symptoms

Bubbles can form anywhere in the body, but symptomatic sensation is most frequently observed in the shoulders, elbows, knees, and ankles.


This table gives symptoms for the different DCS types. The "bends" (joint pain) accounts for about 60 to 70 percent of all altitude DCS cases, with the shoulder being the most common site. These types are classifed medically as DCS I. Neurological symptoms are present in 10 to 15 percent of all DCS cases with headache and visual disturbances the most common. DCS cases with neurological symptoms are generally classified as DCS II. The "chokes" are rare and occur in less than two-percent of all DCS cases. Skin manifestations are present in about 10 to 15 percent of all DCS cases. Neurology is a branch of medicine dealing with disorders of the central and peripheral nervous systems. ...

Table 1. Signs and symptoms of decompression sickness.
DCS Type Bubble Location Signs & Symptoms (Clinical Manifestations)
BENDS Mostly large joints of the body
(elbows, shoulders, hip,
wrists, knees, ankles)
  • Localized deep pain, ranging from mild (a "niggle") to excruciating. Sometimes a dull ache, but rarely a sharp pain.
  • Active and passive motion of the joint aggravates the pain.
  • The pain may be reduced by bending the joint to find a more comfortable position.
  • If caused by altitude, pain can occur immediately or up to many hours later.
NEUROLOGIC Brain
  • Confusion or memory loss
  • Headache
  • Spots in visual field (scotoma), tunnel vision, double vision (diplopia), or blurry vision
  • Unexplained extreme fatigue or behaviour changes
  • Seizures, dizziness, vertigo, nausea, vomiting and unconsciousness may occur, mainly due to labyrinthitis
Spinal Cord
  • Abnormal sensations such as burning, stinging, and tingling around the lower chest and back
  • Symptoms may spread from the feet up and may be accompanied by ascending weakness or paralysis
  • Girdling abdominal or chest pain
Peripheral Nerves
  • Urinary and rectal incontinence
  • Abnormal sensations, such as numbness, burning, stinging and tingling (paresthesia)
  • Muscle weakness or twitching
CHOKES Lungs
  • Burning deep chest pain (under the sternum)
  • Pain is aggravated by breathing
  • Shortness of breath (dyspnea)
  • Dry constant cough
SKIN BENDS Skin
  • Itching usually around the ears, face, neck arms, and upper torso
  • Sensation of tiny insects crawling over the skin
  • Mottled or marbled skin usually around the shoulders, upper chest and abdomen, with itching
  • Swelling of the skin, accompanied by tiny scar-like skin depressions (pitting edema)

The word scotoma is derived from the Greek word for darkness. ... Diplopia, commonly known as double vision, is the perception of two images from a single object. ... For other uses, see Vertigo. ... For other uses, see Nausea (disambiguation). ... Vomiting (or emesis) is the forceful expulsion of the contents of ones stomach through the mouth. ... Labyrinthitis is a balance disorder that usually follows an upper respiratory tract infection (URI). ... Paralysed redirects here. ... Look up incontinence in Wiktionary, the free dictionary. ... Paresthesia or paraesthesia (in British English) is a sensation of tingling, pricking, or numbness of a persons skin with no apparent long-term physical effect, more generally known as the feeling of pins and needles or of a limb being asleep (but not directly related to the phenomenon of... The sternum (from Greek στέρνον, sternon, chest) or breastbone is a long, flat bone located in the center of the thorax (chest). ... Dyspnea (R06. ...

Treatment

Recompression is the only effective treatment for severe DCS, although rest and oxygen (increasing the percentage of oxygen in the air being breathed via a tight fitting oxygen mask) applied to lighter cases can be effective. Recompression is normally carried out in a recompression chamber. In diving, a high-risk alternative is in-water recompression. Breathing 100% oxygen from a tight fitting pressure demand oxygen mask An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. ... A recompression chamber is a pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness. ... In-water recompression is the emergency treatment of decompression sickness (DCS) by sending the diver back underwater to allow the gas bubbles in the tissues, which are causing the symptoms, to disappear. ...


Oxygen first aid treatment is useful for suspected DCS casualties or divers who have made fast ascents or missed decompression stops. Most fully closed-circuit rebreathers can deliver sustained high concentrations of oxygen-rich breathing gas and could be used as an alternative to pure open-circuit oxygen resuscitators. Oxygen first aid kit showing a demand valve and a constant flow mask Oxygen first aid or oxygen administration is a first aid treatment for many medical emergencies involving the organs of respiration and circulation such as heart attack, drowning, carbon monoxide poisoning, decompression illness, lung barotrauma and gas embolism. ... This article is about the breathing apparatus. ... Air is the most common and only natural breathing gas. ... The term Open circuit may refer to: Open-circuit voltage, the difference of electrical potential between two terminals of a device when there is no external load connected Open-circuit scuba, a type of SCUBA-diving equipment where the user breathes from the set and then exhales to the surroundings... A resuscitator is a device using positive pressure to inflate the lungs of an unconscious person who is not breathing, in order to keep him oxygenated and alive. ...


Common pressure reductions that cause DCS

The main cause of DCS is a reduction in the pressure surrounding the body. Common ways in which the required reduction in pressure occur are:

  • leaving a high atmospheric pressure environment
  • rapid ascent through water during a dive
  • ascent to altitude while flying

Leaving a high pressure environment

The original name for DCS was caisson disease; this term was used in the 19th century, when large engineering excavations below the water table, such as with the piers of bridges and with tunnels, had to be done in caissons under pressure to keep water from flooding the excavations. Workers who spend time in high pressure atmospheric pressure conditions are at risk if they leave that environment and reduce the pressure surrounding them. An industrial injury is any disease or bodily damage resulting from working. ... Cross section showing the water table varying with surface topography as well as a perched water table The water table or phreatic surface is the surface where the water pressure is equal to atmospheric pressure. ... For the type of foundation, see Deep foundation. ... This article is about the edifice (including an index to articles on specific bridge types). ... A disused railway tunnel now converted to pedestrian and bicycle use, near Houyet, Belgium A tunnel is an underground passage. ... In engineering, a caisson is a retaining, watertight structure used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, or for the repair of ships. ...


DCS was a major factor during construction of Eads Bridge, when 15 workers died from what was then a mysterious illness, and later during construction of the Brooklyn Bridge, where it incapacitated the project leader Washington Roebling. The Eads Bridge under construction Eads Bridge is a combined road and railway bridge over the Mississippi River at St. ... For other uses, see Brooklyn Bridge (disambiguation). ... Washington Augustus Roebling (May 26, 1837 – July 21, 1926) was an American civil engineer best known for his work on the Brooklyn Bridge, which was initially designed by his father John A. Roebling. ...


Ascent during a dive

DCS is best known as an injury that affects scuba divers. The pressure of the surrounding water increases as the diver descends and reduces as the diver ascends. The risk of DCS increases by diving long or deep without slowly ascending and making the decompression stops needed to eliminate the inert gases normally, although the specific risk factors are not well understood. Some divers seem more susceptible than others under identical conditions. Divers face specific physical and health risks when they go underwater (e. ... A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ...


There have been known cases of bends in snorkellers who have made many deep dives in succession. DCS may be the cause of the disease taravana which affects South Pacific island natives who for centuries have dived without equipment for food and pearls. ... Taravana is a disease among Polynesian island natives who habitually dive deep holding their breath many times in close succession, usually for food or pearls. ... For other uses, see Pearl (disambiguation). ...


Two linked factors contribute to divers' DCS, although the complete relationship of causes is not fully understood:

  • deep or long dives: inert gases in breathing gases, such as nitrogen and helium, are absorbed into the tissues of the body in higher concentrations than normal (Henry's Law) when breathed at high pressure.
  • fast ascents: reducing the ambient pressure, as happens during the ascent, causes the absorbed gases to come back out of solution, and form "micro bubbles" in the blood. Those bubbles will safely leave the body through the lungs if the ascent is slow enough that the volume of bubbles does not rise too high.

The physiologist John Haldane studied this problem in the early 20th century, eventually devising the method of staged, gradual decompression, whereby the pressure on the diver is released slowly enough that the nitrogen comes gradually out of solution without leading to DCS. Bubbles form after every dive: slow ascent and decompression stops simply reduce the volume and number of the bubbles to a level at which there is no injury to the diver. Air is the most common and only natural breathing gas. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... For other uses, see Helium (disambiguation). ... In chemistry, Henrys law is one of the gas laws, formulated by William Henry. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ... John Scott Haldane John Scott Haldane (May 3, 1860 – March 15/March 14, 1936) was a Scottish medical doctor. ... A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ...


Severe cases of decompression sickness can lead to death. Large bubbles of gas impede the flow of oxygen-rich blood to the brain, central nervous system and other vital organs. The human brain In animals, the brain (enkephalos) (Greek for in the skull), is the control center of the central nervous system, responsible for behavior. ... A diagram showing the CNS: 1. ...


Even when the change in pressure causes no immediate symptoms, rapid pressure change can cause permanent bone injury called dysbaric osteonecrosis (DON) "bone cell death from bad pressure". DON can develop from a single exposure to rapid decompression. DON is diagnosed from lesions visible in X-ray images of the bones. Unfortunately, X-rays appear normal for at least 3 months after the permanent damage has occurred; it may take 4 years after the damage has occurred for its effects to become visible in the X-ray images. [1] This article is about the skeletal organs. ... Dysbaric Osteonecrosis Definition Death of a portion of the bone that is thought to be caused by nitrogen embolization blockage of the blood vessels in divers. ...


Avoidance

Decompression tables and dive computers have been developed that help the diver choose depth and duration of decompression stops for a particular dive profile at depth. Dive Tables, Decompression Tables or Tables are printed cards or booklets that allow divers to determine for a particular dive profile and breathing gas, the Decompression stops required for that dive in order to avoid decompression sickness. ... A wrist watch sized dive computer incorporating an electronic compass A dive computer or decompression meter is a device used by a scuba diver to measure the time and depth of a dive so that a safe ascent rate can be calculated and displayed so that the diver can avoid... A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ...


Avoiding decompression sickness is not an exact science. Accidents can occur after relatively shallow and short dives. To reduce the risks, divers should avoid long and deep dives and should ascend slowly. Also, dives requiring decompression stops and dives with less than a 16 hour interval since the previous dive increase the risk of DCS. There are many additional risk factors, such as age, obesity, fatigue, use of alcohol, dehydration and a patent foramen ovale. In addition, flying at high altitude less than 24 hours after a deep dive can be a precipitating factor for decompression illness. A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ... Atrial septal defects (ASD) are a group of congenital heart diseases that enables communication between atria of the heart and may involve the interatrial septum. ...


Astronauts aboard the International Space Station preparing for Extra-vehicular activity "camp out" at low atmospheric pressure (approximately 10 psi = 700 mbar) spending 8 sleeping hours in the airlock chamber before their spacewalk. Their spacesuits can operate at 4.7 psi = 330 mbar for maximum flexibility. U.S. Space Shuttle astronaut Bruce McCandless II using a manned maneuvering unit. ... “ISS” redirects here. ... Astronaut Bruce McCandless on an untethered EVA Extra-vehicular activity (EVA) is work done by an astronaut away from the Earth and outside of his or her spacecraft. ... A millibar (mbar, also mb) is 1/1000th of a bar, a unit for measurement of pressure. ... A glovebox for handling air-sensitive substances. ... Astronaut Bruce McCandless on an untethered EVA Extra-vehicular activity (EVA) is work done by an astronaut away from the Earth and outside of his or her spacecraft. ... Apollo 15 space suit A spacesuit is a complex system of garments, equipment, and environmental systems designed to keep a person alive and comfortable in the harsh environment of outer space. ...


Helium

Nitrogen is not the only breathing gas that causes DCS. Gas mixtures such as trimix and heliox include helium, which can also be implicated in decompression sickness. General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Air is the most common and only natural breathing gas. ... Trimix is a breathing gas, consisting of oxygen, helium and nitrogen, and is often used in deep commercial diving and during the deep phase of dives carried out using Technical diving techniques. ... Heliox is a gas that is composed of a mixture of helium (He) and oxygen (O2). ... For other uses, see Helium (disambiguation). ...


Helium both enters and leaves the body faster than nitrogen, and for dives of three or more hours in duration, the body almost reaches saturation of helium. For such dives the decompression time is shorter than for nitrogen-based breathing gases such as air.


There is some debate as to the decompression effects of helium for shorter duration dives. Most divers do longer decompressions, whereas some groups like the WKPP have been pioneering the use of shorter decompression times by including deep stops. The WKPP is the Woodville Karst Plain Project, a cave diving organisation in the Woodville Karst Plain of Florida, USA. It is notable for its part in the development cave diving techniques, the DIR method of scuba diving and the use of the Halcyon rebreather. ... A Decompression Stop is a period of time a diver must spend at a constant depth in shallow water at the end of a dive in order safely to eliminate inert gases from the divers body to avoid decompression sickness. ...


Decompression time can be significantly shortened by breathing rich nitrox (or pure oxygen in very shallow water) during the decompression phase of the dive. The reason is that the nitrogen outgases at a rate proportional to the difference between the ppN2 (partial pressure of nitrogen) in the diver's body and the ppN2 in the gas that he or she is breathing; but the likelihood of bubbles is proportional to the difference between the ppN2 in the diver's body and the total surrounding air or water pressure. Nitrox refers to any gas mixture composed (excluding trace gases) of nitrogen and oxygen; this includes normal air which is approximately 78% nitrogen and 21% oxygen, with around 1% other gases. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colorless (gas) pale blue (liquid) Standard atomic weight 15. ... In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume. ...


Ascent to altitude

People flying in un-pressurized aircraft at high altitude, such as stowaways, or passengers in a cabin that has experienced rapid decompression, or pilots in an open cockpit, can suffer from decompression sickness. Even Lockheed U-2 pilots experienced altitude DCS in the mid-'50s during the Cold War flying over their targets. Divers who dive and then fly in aircraft are at risk even in pressurized aircraft because the cabin air pressure is less than the air pressure at sea level. The same applies to divers going into higher elevations by land after diving. Image File history File links Emblem-important. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ... Flying machine redirects here. ... High altitude are regions on the Earths surface (or in its atmosphere) that are high above mean sea level. ... The Lockheed U-2, nicknamed Dragon Lady, is a single-engine, high-altitude aircraft flown by the United States Air Force. ... For other uses, see Cold War (disambiguation). ...


Altitude DCS became a commonly observed problem associated with high-altitude balloon and aircraft flights in the 1930s. In present-day aviation, technology allows civilian aircraft (commercial and private) to fly higher and faster than ever before. Though modern aircraft are safer and more reliable, occupants are still subject to the stresses of high-altitude flight and the unique problems that go with these lofty heights. A century-and-a-half after the first DCS case was described, our understanding of DCS has improved and a body of knowledge has accumulated; however, this problem is far from being solved. Altitude DCS is still a risk to the occupants of modern aircraft.


There is no specific altitude threshold that can be considered safe for everyone below which it can be assured that no one will develop altitude DCS. However, there is very little evidence of altitude DCS occurring among healthy individuals at pressure altitudes below 18,000 feet who have not been scuba diving. Individual exposures to pressure altitudes between 18,000 and 25,000 feet have shown a low occurrence of altitude DCS. Most cases of altitude DCS occur among individuals exposed to pressure altitudes of 25,000 feet or higher. A US Air Force study of altitude DCS cases reported that only 13 percent occurred below 25,000 feet The higher the altitude of exposure, the greater the risk of developing altitude DCS. It is important to clarify that although exposures to incremental altitudes above 18,000 feet show an incremental risk of altitude DCS they do not show a direct relationship with the severity of the various types of DCS (see Table 1). In aviation, pressure altitude is the indicated altitude when an altimeter is set to 1013 hPa (29. ...


Arterial gas embolism and DCS have very similar treatment because they are both the result of gas bubbles in the body. Their spectra of symptoms also overlap, although those from arterial gas embolism are more severe because they often cause infarction and tissue death as noted above. In a diving context, the two are joined under the general term of decompression illness. Another term, dysbarism, encompasses decompression sickness, arterial gas embolism, and barotrauma. Description An air embolism, or more generally gas embolism, is a medical condition caused by gas bubbles in the bloodstream. ... This article does not adequately cite its references or sources. ... This article needs cleanup. ... Dysbarism refers to medical conditions resulting from changes in ambient pressure. ... Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid. ...


Ascent to altitude can happen without flying in places such as the Ethiopia and Eritrea highland (8000 feet = about 1.5 miles above sea level) and the Peru and Bolivia altiplano and Tibet (2 to 3 miles above sea level). Puno, Peru, is one of larger cities of the Altiplano. ... This article is about historical/cultural Tibet. ...


Medical treatment

Mild cases of the "bends" and skin bends (excluding mottled or marbled skin appearance) may disappear during descent from high altitude but still require medical evaluation. If the signs and symptoms persist during descent or reappear at ground level, it is necessary to provide hyperbaric oxygen treatment immediately (100-percent oxygen delivered in a high-pressure chamber). Neurological DCS, the "chokes," and skin bends with mottled or marbled skin lesions (see Table 1) should always be treated with hyperbaric oxygenation. These conditions are very serious and potentially fatal if untreated. This article does not cite any references or sources. ...


Effects of breathing pure oxygen

Breathing pure oxygen to remove nitrogen from the bloodstream

One of the most significant breakthroughs in altitude DCS research was oxygen pre-breathing. Breathing pure oxygen before exposure to a low-barometric pressure decreases the risk of developing altitude DCS. Oxygen pre-breathing promotes the elimination or washout of nitrogen from body tissues. Pre-breathing pure oxygen for 30 minutes before starting ascent to altitude reduces the risk of altitude DCS for short exposures (10 to 30 minutes only) to altitudes between 18,000 and 43,000 feet. However, oxygen pre-breathing has to be continued without interruption with in-flight, pure oxygen to provide effective protection against altitude DCS. Furthermore, it is very important to understand that breathing pure oxygen only during flight (ascent, en route, descent) does not decrease the risk of altitude DCS, and should not be used instead of oxygen pre-breathing. Image File history File links Oxymask. ... Image File history File links Oxymask. ...


Although pure oxygen pre-breathing is an effective method to protect against altitude DCS, it is logistically complicated and expensive for the protection of civil aviation flyers, either commercial or private. Therefore, it is only used now by military flight crews and astronauts for their protection during high altitude and space operations.


Scuba diving before flying

The rule about decompression sickness risk on ascending to lower surrounding pressure, does not stop at sea level (even though decompression tables stop at sea level), but continues when a diver soon after diving goes into air pressure much less than at sea level. Altitude DCS can occur during exposure to altitudes as low as 5,000 feet or less. This can happen:

  1. In an airliner at high altitude the cabin pressure is usually not at full sea level pressure, but like the air pressure at approx. 8,000 feet altitude.
  2. At high altitudes on land: e.g. if you scuba dive in Eritrea, and then go onto the Asmara plateau (where Eritrea's main airport is), which is about 8000 feet or 1.5 miles or 2400 meters above sea level.
  3. Occasionally in cave diving, "Torricellian chambers" are found; they are full of water at less than atmospheric pressure. They arise when the water level drops and there is no way for air to get into the chamber.

An Airbus A340 airliner operated by Air Jamaica An airliner is a large fixed-wing aircraft with the primary function of transporting paying passengers. ... Asmara (English) (Geez: አሥመራ Asmera, formerly known as Asmera, or in Arabic: Asmaraa) is the capital city and largest settlement in Eritrea, home to a population of around 579,000 people. ... Inside the cave at Cave Stream, New Zealand Caving is the recreational sport of exploring caves. ... In cave diving, a Torricellian chamber is a cave chamber full of water at less than atmospheric pressure. ...

What to do if altitude DCS occurs

  • Put on your oxygen mask immediately and switch the regulator to 100% oxygen.
  • Begin an emergency descent and land as soon as possible. Even if the symptoms disappear during descent, you should still land and seek medical evaluation while continuing to breathe oxygen.
  • If one of your symptoms is joint pain, keep the affected area still; do not try to work pain out by moving the joint around.
  • Upon landing seek medical assistance from an aviation authority medical officer, aviation medical examiner (AME), military flight surgeon, or a hyperbaric medicine specialist. Be aware that a physician not specialized in aviation or hypobaric medicine may not be familiar with this type of medical problem. Therefore, be your own advocate.
  • Definitive medical treatment may involve the use of a hyperbaric chamber operated by specially trained personnel.
  • Delayed signs and symptoms of altitude DCS can occur after return to ground level whether or not they were present during flight.

Breathing 100% oxygen from a tight fitting pressure demand oxygen mask An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. ...

Things to remember

  • Altitude DCS is a risk every time you fly in an un-pressurized aircraft above 18,000 feet (or at lower altitude if you scuba dive prior to the flight).
  • Be familiar with the signs and symptoms of altitude DCS (see Table 1). Monitor all aircraft occupants, including yourself, any time you fly an unpressurized aircraft above 18,000 feet.
  • Avoid unnecessary strenuous physical activity prior to flying an un-pressurized aircraft above 18,000 feet, and for 24 h after the flight.
  • Even if you are flying a pressurized aircraft, altitude DCS can occur as a result of sudden loss of cabin pressure (in-flight rapid decompression).
  • After exposure to an in-flight rapid decompression, do not fly for at least 24 h. In the meantime, stay vigilant for the possible onset of delayed symptoms or signs of altitude DCS. If you present delayed symptoms or signs of altitude DCS, seek medical attention at once.
  • Keep in mind that breathing 100% oxygen during flight (ascent, en route, descent) without oxygen pre-breathing before take off does not prevent altitude DCS.
  • Do not ignore any symptoms or signs that go away during the descent. This could confirm that you are suffering altitude DCS. You should be medically evaluated as soon as possible.
  • If there is any indication that you may have experienced altitude DCS, do not fly again until you are cleared to do so by an aviation authority medical officer, an aviation medical examiner, a military flight surgeon, or a hyperbaric medicine specialist.
  • Allow at least 24 hours to elapse between scuba diving and flying.
  • Be prepared for a future emergency by finding where hyperbaric chambers are available in your area of operations. However, keep in mind that not all of the available hyperbaric treatment facilities have personnel qualified to handle altitude DCS emergencies. To obtain information on the locations of hyperbaric treatment facilities capable of handling altitude DCS emergencies, call the Diver's Alert Network at (USA phone number) (919) 684-8111.

Image File history File links Broom_icon. ... Hyperbaric oxygen therapy (HBOT) is the medical use of oxygen at a higher than atmospheric pressure. ...

Decompression sickness in popular culture

  • A diver with decompression sickness flying in an aircraft was part of the plot in the episode Airborne of House, M.D., first aired Tuesday April 11, 2007.
  • Rock band Radiohead released an album entitled The Bends, a reference to decompression sickness.
  • In Tom Clancy's novel Without Remorse, protagonist John Kelly brutally tortures a drug dealer by using a recompression chamber to induce severe (and ultimately fatal) barotrauma.
  • Mr. Bungle released a song entitled "The Bends," also in reference to decompression sickness.
  • Decompression sickness played a part in the anime visual novel "Ever 17"
  • A character in the series "Dive" by Gordan Korman experiences a case of Decompression sickness.
  • In an episode of "Jackie Chan Adventures" titled Clash of the Titanics, Jackie experienced decompression sickness
  • Roger Bochs, a character in the Marvel Comics series Alpha Flight, experiences decompression sickness after battling alongside the Avengers in Atlantis.

Airborne is the eighteenth episode of the third season of House and the sixty-fourth episode overall. ... House, also known as House, M.D., is an American medical drama television series created by David Shore and executive produced by Shore and film director Bryan Singer. ... is the 101st day of the year (102nd in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... Radiohead are an English rock band. ... This article is about the album by Radiohead. ... For the member of the Irish folk band The Clancy Brothers, see Tom Clancy (singer) and for the American Celticist, see Thomas Owen Clancy. ... Without Remorse is a novel by Tom Clancy set in 1971, in the middle of the Vietnam War. ... Barotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding gas or liquid. ... Mr. ... Ever17 ―the out of infinity― ) is a Japanese romance visual novel from KID originally released on August 29, 2002 for the PS2 and Dreamcast. ... Jackie Chan Adventures was a successful childrens animated television series chronicling the adventures of a fictionalized version of action film star Jackie Chan. ... Box (Roger Bochs) is a fictional character, a robot from the fictional Marvel Comics universe. ... This article is about the comic book company. ... Alpha Flight is a Marvel Comics superhero team, noteworthy for being one of the few Canadian superhero teams. ... The Avengers are a fictional superhero team appearing in comic books published by Marvel Comics. ... Atlantis is a fictional location in the Marvel Comics Universe and the DC Comics Universe. ...

References

  1. ^ http://depts.washington.edu/adai/pubs/pres/LeighRSAPoster.pdf

External links


  Results from FactBites:
 
Decompression sickness - Wikipedia, the free encyclopedia (3329 words)
Decompression sickness, (DCS), diver's disease, the bends, or caisson disease is the name given to a variety of symptoms suffered by a person exposed to a reduction in the pressure surrounding their body.
Decompression tables and dive computers have been developed that help the diver choose depth and duration of decompression stops for a particular dive profile at depth.
Decompression time can be significantly shortened by breathing nitrox (or pure oxygen if in very shallow water), during the decompression phase of the dive.
Decompression Sickness: Diving and Compressed Air Injuries: Merck Manual Home Edition (1820 words)
Decompression sickness (decompression illness, caisson disease, the bends) is a disorder in which nitrogen dissolved in the blood and tissues by high pressure forms bubbles as pressure decreases.
The risk of developing decompression sickness increases with increasing pressure (that is, the depth of the dive) and with the length of time spent in a pressurized environment.
The inability to eliminate decompression sickness may be because the published tables and computer programs do not completely account for the variation in risk factors among different divers or because some people fail to obey the recommendations of the tables or computer.
  More results at FactBites »

 
 

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