In-water recompression
Encyclopedia
In-water recompression or underwater oxygen treatment (IWR) is the emergency treatment of decompression sickness
(DCS) of sending the diver
back underwater
to allow the gas bubbles in the tissues, which are causing the symptoms, to resolve. It is a risk
y procedure that should only ever be used when the time to travel to the nearest recompression chamber is too long to save the victim's life.
Carrying out in-water recompression when there is a nearby recompression chamber or without special equipment and training is never a favoured option. The risk of the procedure comes from the fact that a diver suffering from DCS is seriously ill and may become paralysed
, unconscious
or stop breathing
whilst under water. Any one of these events is likely to result in the diver drowning
or further injury to the diver during a subsequent rescue to the surface.
. Significant delay to treatment, difficult transport, and facilities with limited experience may lead one to consider on site treatment. Surface oxygen for first aid has been proven to improve the efficacy of recompression and decreased the number of recompression treatments required when administered within four hours post dive. IWR to 9 m breathing oxygen is one option that has shown success over the years IWR is not without risk and should be undertaken with certain precautions. IWR would only be suitable for an organised and disciplined group of divers with suitable equipment and practical training in the procedure.
The principle behind IWR treatment is the same as that behind the treatment of DCS in a recompression chamber: an increase in ambient pressure will reduce the volume of the bubbles allowing better blood transport downstream of the bubbles. If the casualty can breathe pure oxygen
further improvements will occur because the increase in the proportion of oxygen in the blood may keep previously oxygen-starved tissues alive and the oxygen will remove other inert gases from the bubbles making the bubbles smaller.
was charged to supervise the then, non-sanctioned, practice of IWR. This charge was in response to the very long delays that were associated between the presentation of DCS and recompression treatment. Dr Edmonds also described the debates about underwater oxygen treatment for DCS that are not unlike current concerns.
. Each of these methods have several commonalities including the use of a full face mask, a tender to supervise the diver during treatment, a weighted recompression line and a means of communication. The history of the three older methods for providing oxygen at 9m (30 fsw) was described in great detail by Drs. Pyle and Youngblood. The fourth method for providing oxygen at 7.5 m (25 fsw) was described by Pyle at the 48th Annual UHMS Workshop on In-water Recompression in 1999. The Clipperton method involves recompression to 9m (30 fsw) while the Clipperton(a) rebreather
method involves a recompression to 30m (98 fsw).
in the 1960s in response to their need for treatment in remote locations far away from recompression chambers. It was the shallow portion of the table developed for recompression chamber use.
Oxygen is breathed the entire portion of the treatment without any air breaks and is followed by alternating periods (12 hours) of oxygen and air breathing on the surface.
, 1,300 km from the Mexican coasts. The two versions are based on the equipment available for treatment with the Clipperton(a) table being designed for use with rebreathers.
Both methods begin with 10 minutes of surface oxygen. For the Clipperton IWR table, oxygen is then breathed the entire portion of the treatment without any air breaks. For the Clipperton IWR table, descent is made to the initial treatment depth maintaining a partial pressure
of 1.4 ATA. Oxygen breathing on the surface for 6 hours post treatment and intravenous
fluids are also administered following both treatment tables.
's diving fishermen.
The initial portion of the treatment involves descent on air to the depth of relief plus 30 fsw or a maximum of 165 fsw for ten minutes. Ascent from initial treatment depth to 30 fsw occurs over 10 minutes. The diver then completes the treatment breathing oxygen and is followed by oxygen breathing on the surface for 30 minutes post treatment.
The Hawaiian IWR Table with Pyle modifications can be found in the proceedings of the DAN 2008 Technical Diving Conference (In Press) or through download from DAN here.
This method begins with a 10 minute surface oxygen evaluation period. Compression to 25 fsw on oxygen for another 10 minute evaluation period. The table is best described by the treatment algorithm
(Pyle IWR algorithm). This table does include alternating air breathing periods or "air breaks".
Oxygen is breathed the entire portion of the treatment without any air breaks and is followed by 3 hours of oxygen breathing on the surface.
's 2008 accident report. The report also notes that whilst the reported incidents showed very little success, "[w]e must recognize that these calls were mostly because the attemped IWR failed. In case the IWR were successful, [the] diver would not have called to report the event. Thus we do not know how often IWR may have been used successfully."
Decompression sickness
Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...
(DCS) of sending the diver
Underwater diving
Underwater diving is the practice of going underwater, either with breathing apparatus or by breath-holding .Recreational diving is a popular activity...
back underwater
Underwater
Underwater is a term describing the realm below the surface of water where the water exists in a natural feature such as an ocean, sea, lake, pond, or river. Three quarters of the planet Earth is covered by water...
to allow the gas bubbles in the tissues, which are causing the symptoms, to resolve. It is a risk
Risk
Risk is the potential that a chosen action or activity will lead to a loss . The notion implies that a choice having an influence on the outcome exists . Potential losses themselves may also be called "risks"...
y procedure that should only ever be used when the time to travel to the nearest recompression chamber is too long to save the victim's life.
Carrying out in-water recompression when there is a nearby recompression chamber or without special equipment and training is never a favoured option. The risk of the procedure comes from the fact that a diver suffering from DCS is seriously ill and may become paralysed
Paralysed
Paralysed or Paralyzed may refer to:*the state of paralysis, the complete loss of muscle function for one or more muscle groups- In music :*"Paralyzed" *"Paralysed", a song by Gang of Four from their 1981 album Solid Gold...
, unconscious
Unconsciousness
Unconsciousness is the condition of being not conscious—in a mental state that involves complete or near-complete lack of responsiveness to people and other environmental stimuli. Being in a comatose state or coma is a type of unconsciousness. Fainting due to a drop in blood pressure and a...
or stop breathing
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
whilst under water. Any one of these events is likely to result in the diver drowning
Drowning
Drowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....
or further injury to the diver during a subsequent rescue to the surface.
Background
Treatment of DCS utilizing the US Navy Treatment Table 6 with oxygen at 18m is a standard of careStandard of care
In tort law, the standard of care is the degree of prudence and caution required of an individual who is under a duty of care.The requirements of the standard are closely dependent on circumstances. Whether the standard of care has been breached is determined by the trier of fact, and is usually...
. Significant delay to treatment, difficult transport, and facilities with limited experience may lead one to consider on site treatment. Surface oxygen for first aid has been proven to improve the efficacy of recompression and decreased the number of recompression treatments required when administered within four hours post dive. IWR to 9 m breathing oxygen is one option that has shown success over the years IWR is not without risk and should be undertaken with certain precautions. IWR would only be suitable for an organised and disciplined group of divers with suitable equipment and practical training in the procedure.
The principle behind IWR treatment is the same as that behind the treatment of DCS in a recompression chamber: an increase in ambient pressure will reduce the volume of the bubbles allowing better blood transport downstream of the bubbles. If the casualty can breathe pure oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
further improvements will occur because the increase in the proportion of oxygen in the blood may keep previously oxygen-starved tissues alive and the oxygen will remove other inert gases from the bubbles making the bubbles smaller.
Brief History and Risks
The Royal Australian Navy School of Underwater MedicineRoyal Australian Navy School of Underwater Medicine
The Royal Australian Navy School of Underwater Medicine is based at Sydney, Australia.The Diving Section of HMAS Watson was afforded by the District Medical Officer, Surgeon Lieutenant Commander Shane A.C. Watson, whose interest in diving led to research in injuries related to marine animals...
was charged to supervise the then, non-sanctioned, practice of IWR. This charge was in response to the very long delays that were associated between the presentation of DCS and recompression treatment. Dr Edmonds also described the debates about underwater oxygen treatment for DCS that are not unlike current concerns.
- Inappropriate cases for treatment,
- Oxygen toxicityOxygen toxicityOxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen at elevated partial pressures. It is also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning...
, - Emergency Termination of Treatment,
- HypothermiaHypothermiaHypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
- Adequacy of Equipment in Remote Areas,
- Seasickness,
- Operator Expertise and Training,
- Safety of the Diving Attendant and the Boat Tenders,
- Requirement for Medical Supervision,
- Transport Availability,
- Misuse of Equipment,
- Pulmonary BarotraumaBarotraumaBarotrauma is physical damage to body tissues caused by a difference in pressure between an air space inside or beside the body and the surrounding fluid...
Cases.
Equipment
Some of the equipment needed includes:- a means of securely holding the casualty at a measured depth, such as a harness and 20 metre line with a 20 kg lead weight at the bottom and 40 litre buoy at the top
- a means of allowing the casualty to ascend slowly, such as loops in the line to which the harness could be clipped
- full face diving maskFull face diving maskA full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece or demand valve that provides the diver with breathing gas...
s for the casualty and for an in-water tending diver including two-way communication to the surface and an umbilical gas supply - surface suppliedSurface supplied divingSurface supplied diving refers to divers using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel sometimes indirectly via a diving bell...
breathing gasBreathing gasBreathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...
es including pure oxygenOxygenOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
and air delivered to the casualty by umbilical - voice communications equipment to the divers
- use IWR treatment "table"
In-Water Recompression Tables
Six IWR treatment tables have been published in the scientific literatureScientific literature
Scientific literature comprises scientific publications that report original empirical and theoretical work in the natural and social sciences, and within a scientific field is often abbreviated as the literature. Academic publishing is the process of placing the results of one's research into the...
. Each of these methods have several commonalities including the use of a full face mask, a tender to supervise the diver during treatment, a weighted recompression line and a means of communication. The history of the three older methods for providing oxygen at 9m (30 fsw) was described in great detail by Drs. Pyle and Youngblood. The fourth method for providing oxygen at 7.5 m (25 fsw) was described by Pyle at the 48th Annual UHMS Workshop on In-water Recompression in 1999. The Clipperton method involves recompression to 9m (30 fsw) while the Clipperton(a) rebreather
Rebreather
A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...
method involves a recompression to 30m (98 fsw).
Australian In-water Recompression Table
The Australian IWR Tables were developed by the Royal Australian NavyRoyal Australian Navy
The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...
in the 1960s in response to their need for treatment in remote locations far away from recompression chambers. It was the shallow portion of the table developed for recompression chamber use.
Oxygen is breathed the entire portion of the treatment without any air breaks and is followed by alternating periods (12 hours) of oxygen and air breathing on the surface.
Clipperton In-water Recompression Tables
The Clipperton and Clipperton(a) methods were developed for use on a scientific mission to the atoll of ClippertonClipperton Island
Clipperton Island is an uninhabited nine-square-kilometre coral atoll in the eastern Pacific Ocean, southwest of Mexico and west of Central America, at...
, 1,300 km from the Mexican coasts. The two versions are based on the equipment available for treatment with the Clipperton(a) table being designed for use with rebreathers.
Both methods begin with 10 minutes of surface oxygen. For the Clipperton IWR table, oxygen is then breathed the entire portion of the treatment without any air breaks. For the Clipperton IWR table, descent is made to the initial treatment depth maintaining a partial pressure
Partial pressure
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. The total pressure of a gas mixture is the sum of the partial pressures of each individual gas in the mixture....
of 1.4 ATA. Oxygen breathing on the surface for 6 hours post treatment and intravenous
Intravenous therapy
Intravenous therapy or IV therapy is the infusion of liquid substances directly into a vein. The word intravenous simply means "within a vein". Therapies administered intravenously are often called specialty pharmaceuticals...
fluids are also administered following both treatment tables.
Hawaiian In-water Recompression Table
The Hawaiian IWR table was first described by Farm et al. while studying the diving habits of HawaiiHawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
's diving fishermen.
The initial portion of the treatment involves descent on air to the depth of relief plus 30 fsw or a maximum of 165 fsw for ten minutes. Ascent from initial treatment depth to 30 fsw occurs over 10 minutes. The diver then completes the treatment breathing oxygen and is followed by oxygen breathing on the surface for 30 minutes post treatment.
The Hawaiian IWR Table with Pyle modifications can be found in the proceedings of the DAN 2008 Technical Diving Conference (In Press) or through download from DAN here.
Pyle In-water Recompression Table
The Pyle IWR table was developed by Dr. Richard Pyle as a method for treating DCS in the field following scientific dives.This method begins with a 10 minute surface oxygen evaluation period. Compression to 25 fsw on oxygen for another 10 minute evaluation period. The table is best described by the treatment algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
(Pyle IWR algorithm). This table does include alternating air breathing periods or "air breaks".
US Navy In-water Recompression Tables
The US Navy developed two IWR treatment tables. The table used depends on the symptoms diagnosed by the medical officer.Oxygen is breathed the entire portion of the treatment without any air breaks and is followed by 3 hours of oxygen breathing on the surface.
"Informal" in-water recompression
Although in-water recompression is regarded as risky, and to be avoided, there is increasing evidence that technical divers who surface and demonstrate mild DCS symptoms may often get back into the water and breathe pure oxygen at a depth 20 feet/6 meters for a period of time to seek to alleviate the symptoms. This trend is noted in paragraph 3.6.5 of DANDivers Alert Network
The Divers Alert Network is a non-profit 501 organization devoted to assisting divers in need. The Research department conducts significant medical research on recreational scuba diving safety...
's 2008 accident report. The report also notes that whilst the reported incidents showed very little success, "[w]e must recognize that these calls were mostly because the attemped IWR failed. In case the IWR were successful, [the] diver would not have called to report the event. Thus we do not know how often IWR may have been used successfully."