German yachtsman latest victim of decompression sickness
LABUAN: A 61-year-old German yachtsman has become the latest victim of decompression sickness and is seeking treatment at the Navy’s recompression chamber here. Berekoven Hans Joachim was leisure diving off Kuching, Sarawak when he came across a big stingray. Fearing for his safety after what had happened to Steve Irwin (Australia’s famous Crocodile Hunter), he made a fast ascend to the sea surface and later felt numbness around his legs. “I have never seen so much fish in my life and suddenly a monstrous stingray which seemed to be agitated by the fish, came reálly close to me. I saw the barb that was about six inches long and the thought of Steve Irwin and his fatal encounter flashed through my mind,” said Berekoven yesterday. Re1ating his experience that took place while wreck-diving 20km off Kuching, Joachim, who has a sheep and wine farm in Monaro, Queensland in Australia and currently sailing his yacht, Southern Sun, around the South East Asian region, added: “I panicked and deflated my buoyancy vest. I ascended too fast!” The sailor said that he felt numbness around his legs when he got aboard his yacht but his diving buddy and him initially thought it was just over exertion. However, when it got worse, the hospital in Kuching advised him that he should go for the hyperbaric oxygen treatment that is available at the Royal Malaysian Navy’s dive centre here. Decompression sickness, also called the Bends (the term likely describes the bent-over posture of the suffering diver) is a dangerous and occasionally lethal condition caused by nitrogen bubbles that form in the blood and other tissues of divers who surface too quickly, without decompression stops. Joachim, who was diving 25 metres deep with proper scuba equipment that he carries on board Southern Sun, expressed his appreciation for the Navy’s facility. He is among the lucky ones who are quite certain to fully recover. The same however cannot be said of Mohamad Asri Bin Dayan, 27, of Pulau Tiga and 23-year-old Mohd Arah Bin Kassim, a Pulau Gaya village fisherman. Mohamad Asri is still paralyzed, waist downwards, in the intensive care unit of the hospital here while Mohd Arah is not even able to breath independently and unconscious at the Queen Elizabeth Hospital in Kota Kinabalu. Both were diving for fish the risky primitive way — breathing through garden hoses attached to old automotive-spraying compressors; diving far too deep (50 to 70 meters) and far too long, without safety considerations. Publicity on the two fishermen’s cases has sparked public outcry that these people are not only endangering their own lives but also destroying the State’s marine life by carrying out unscrupulous fish bombing and poisoning activities. Meanwhile, Rear Admiral Datuk Ahmad Kamarulzaman Hj Ahmad Badaruddin, the Commander of Naval Region Two encompassing Sabah, Labuan and Sarawak waters, said that the Navy is always ready and willing to assist with their recompression chambers, one located in Labuan and the other in Semporna, but action should be taken and awareness campaigns organized to curb the problem. Lt Kamid Bin Sulaiman leads the team from the naval base in Sabah to manage the recompression facility for the latest victim.
Decompression sickness
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 reduction in the
pressure surrounding their body. It is a type of
diving hazard and
dysbarism.
Introduction
Decompression sickness can happen in these situations:
A diver ascends rapidly 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 maintained to 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.
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.
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.
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.
History
Wikisource has an original article from the
1911 Encyclopædia Britannica about:
Caisson Disease1841: 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.
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.
Rate of Air Consumption: If you tend to consume more air than what may be considered "normal" for scuba diving, you will certainly be more susceptible to DCS if you skirt the no-decompression limits.
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 and decreased
motor coordination/
mental acuity, 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 staying hydrated 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).
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.
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
labyrinthitisSpinal 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
paralysisGirdling abdominal or chest pain
Peripheral Nerves
Urinary and rectal
incontinenceAbnormal 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)
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.
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.
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.
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.
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.
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.
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.
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.
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]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.
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.
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.
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.
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.
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.
a baazar in Sembulan, Kota Kinabalu, Sabah
