Hyperbaric treatment schedules

Hyperbaric treatment schedules or hyperbaric treatment tables, are planned sequences of events in chronological order for hyperbaric pressure exposures specifying the pressure profile over time and the breathing gas to be used during specified periods, for medical treatment. Hyperbaric therapy is based on exposure to pressures greater than normal atmospheric pressure, and in many cases the use of breathing gases with oxygen content greater than that of air.
A large number of hyperbaric treatment schedules are intended primarily for treatment of underwater divers and hyperbaric workers who present symptoms of decompression illness during or after a dive or hyperbaric shift, but hyperbaric oxygen therapy may also be used for other conditions.
Most hyperbaric treatment is done in hyperbaric chambers where environmental hazards can be controlled, but occasionally treatment is done in the field by in-water recompression when a suitable chamber cannot be reached in time. The risks of in-water recompression include maintaining gas supplies for multiple divers and people able to care for a sick patient in the water for an extended period of time.
Background.
Recompression of diving casualties presenting symptoms of decompression sickness has been the treatment of choice since the late 1800s. This acceptance was primarily based on clinical experience.
John Scott Haldane's decompression procedures and the associated tables developed in the early 1900s greatly reduced the incidence of decompression sickness, but did not eliminate it entirely. It was, and remains, necessary to treat incidences of decompression sickness.
Hyperbaric chamber recompression.
During the building of the Brooklyn Bridge, workers with decompression sickness were recompressed in an iron chamber built for this purpose. They were recompressed to the same pressure they had been exposed to while working, and when the pain was relieved, decompressed slowly to atmospheric pressure.
Although recompression and slow decompression were the accepted treatment, there was not yet a standard for either the recompression pressure or the rate of decompression. This changed when the first standard table for recompression treatment with air was published in the US Navy Diving Manual in 1924. These tables were not entirely successful - there was a 50% relapse rate, and the treatment, though fairly effective for mild cases, was less effective in serious cases.
1945 series of human experiments..
Field results showed that the 1944 oxygen treatment table was not yet satisfactory, so a series of tests were conducted by staff from the Navy Medical Research Institute and the Navy Experimental Diving Unit using human subjects to verify and modify the treatment tables.
Tests were conducted using the 100-foot air-oxygen treatment table and the 100-foot air treatment table, which were found to be satisfactory. Other tables were extended until they produced satisfactory results. The resulting tables were used as the standard treatment for the next 20 years, and these tables and slight modifications were adopted by other navies and industry. Over time, evidence accumulated that the success of these table for severe decompression sickness was not very good.
These low success rates led to the development of the oxygen treatment table by Goodman and Workman in 1965, variations of which are still in general use as the definitive treatment for most cases of decompression sickness.
In water recompression.
"History: Pearl divers"
Treatment of DCS utilizing the US Navy Treatment Table 6 with oxygen at 18m is a standard of care. 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.
Applications.
Treatment of decompression sickness, arterial gas embolism, and other medical applications.
Equipment.
Recompression chamber.
The type of chamber which can be used depends on the maximum pressure required for the schedule, and what gases are used for treatment. Most treatment protocols for diving injuries require an attendant in the chamber, and a medical lock to transfer medical supplies into the chamber while under pressure.
Monoplace chambers.
Outside of the diving industry, most chambers are intended for a single occupant, and not all of them are fitted with built-in breathing systems (BIBS). This limits the schedules which can be safely used in them. Some schedules have been developed specifically for hyperbaric oxygen treatment in monoplace chambers, and some hyperbaric treatment schedules nominally intended for chambers with BIBS have been shown to be acceptable for use without air breaks if the preferred facilities are not available.
Treatment gases.
Originally therapeutic recompression was done using air as the only breathing gas, and this is reflected in several of the tables detailed below. However work by Yarbrough and Behnke showed that use of oxygen as a treatment gas is usually beneficial and this has become the standard of care for treatment of DCS. Pure oxygen can be used at pressures up to 60 fsw (18 msw) with acceptable risk of CNS oxygen toxicity, which generally has acceptable consequences in the chamber environment when an inside tender is at hand. At greater pressures, treatment gas mixtures using Nitrogen or Helium as a diluent to limit partial pressure of oxygen to 3 ata (3& bar) or less are preferred to air as they are more effective both at elimination of inert gases and oxygenating injured tissues in comparison with air. Nitrox and Heliox mixtures are recommended by the US Navy for 
treatment gases at pressures exceeding 60 fsw (18 msw), and Heliox is preferred at pressures exceeding 165 fsw (50 msw) to reduce nitrogen narcosis. 
High oxygen fraction gas mixtures may also be substituted for pure oxygen at pressures less than 60 fsw if the patient does not tolerate 100% oxygen.
Built in breathing system.
Treatment gases are generally oxygen or oxygen rich mixtures which would constitute an unacceptable fire hazard if used as the chamber gas. Chamber oxygen concentration is limited due to fire hazard and the high risk of fatality or severe injury in the event of a chamber fire. US Navy specifications for oxygen content of chamber air allow a range from 19% to 25%. If the oxygen fraction rises above this limit the chamber must be ventilated with air to bring the concentration to an acceptable level. To minimize the requirement for venting, oxygen-rich treatment gases are usually provided to the patient by built in breathing system (BIBS) masks, which vent exhaled gas outside the chamber. BIBS masks are provided with straps to hold them in place over the mouth and nose, but are often held in place manually, so they will fall away if the user has an oxygen toxicity convulsion.
BIBS masks provide gas on demand (inhalation), much like a diving regulator, and use a similar system to control outflow to the normobaric environment. They are connected to supply lines plumbed through the pressure hull of the chamber, valved on both sides, and supplied from banks of storage cylinders, usually kept near the chamber. The BIBS system is normally used with medical oxygen, but can be connected to other breathing gases as required. Chamber gas oxygen content is usually monitored by bleeding chamber gas past an electro-galvanic oxygen sensor cell.
Units of measurement used in hyperbaric treatment.
The commonly used units of pressure for hyperbaric treatment are metres of sea water (msw) and feet of sea water (fsw) which indicate the pressure of treatment in terms of the height of water column that would be supported in a manometer. These units are also used for measuring the depth of a surface supplied diver using a and directly relate the pressure to an equivalent depth. The pressure gauges used on diving chambers are often calibrated in both of these units. Elapsed time of treatment is usually recorded in minutes, or hours and minutes, and may be measured from the start of pressurisation, or from the time when treatment pressure is reached.
Hyperbaric chamber treatment schedules.
The schedules listed here include both historical procedures and schedules currently in use. As a general rule, more recent tables from the same source have a greater success rate than the superseded schedules. Some of the older procedures are now considered to be dangerous.
US Navy 1943 100-foot Air Treatment Table.
Use: Treatment of decompression sickness where relief is obtained at or less than 66 fsw.
US Navy 1943 150-foot Air Treatment Table.
Use: Treatment of decompression sickness where relief is obtained at or less than 116 fsw.
US Navy 1943 200-foot Air Treatment Table.
Use: Treatment of decompression sickness where relief is obtained at or less than 166 fsw.
US Navy 1943 250-foot Air Treatment Table.
Use: Treatment of decompression sickness where relief is obtained at or less than 216 fsw.
US Navy 1943 300-foot Air Treatment Table.
Use: Treatment of decompression sickness where relief is obtained at or less than 266 fsw.
US Navy 1944 Long Air Recompression Treatment Table.
Use: Treatment of moderate to severe decompression sickness when oxygen is not available or the patient cannot tolerate the elevated oxygen partial pressure.
US Navy 1944 Long Air Recompression Treatment Table with Oxygen.
Use: Treatment of moderate to severe decompression sickness when oxygen is available.
US Navy 1944 Short Air Recompression Treatment Table.
Use: Treatment of mild decompression sickness when oxygen is not available or the patient cannot tolerate the elevated oxygen partial pressure.
US Navy 1944 Short Oxygen Recompression Treatment Table.
Use: Treatment of mild decompression sickness.
US Navy Recompression Treatment Table 1.
Use: Treatment of pain only decompression sickness.
US Navy Air Treatment Table 1A.
Table 1A is included in the US Navy Diving Manual Revision 6 and is authorized for use as a last resort when oxygen is not available. This table has been revised by decreasing the ascent rate from 1 minute between stops to 1 fsw per minute since the original was published in 1958.
Use: For treatment of pain only decompression sickness.
US Navy Recompression Treatment Table 2.
Use: Treatment of pain-only decompression sickness.
US Navy Air Treatment Table 2a.
Table 2A is included in the US Navy Diving Manual Revision 6 and is authorized for use as a last resort when oxygen is not available. This table has been revised by decreasing the ascent rate from 1 minute between stops to 1 fsw per minute since the original was published in 1958.
Use: Treatment of pain only decompression sickness when oxygen cannot be used.
US Navy Air Treatment Table 3.
Table 3 is included in the US Navy Diving Manual Revision 6 and is authorized for use as a last resort when oxygen is not available. This table has been revised by decreasing the ascent rate from 1 minute between stops to 1 fsw per minute since the original was published in 1958.
Use: Treatment of serious symptoms when oxygen cannot be used and symptoms are relieved within 30 minutes at 165 feet
US Navy Recompression Treatment Table 4.
This table is in the US Navy Diving Manual Revision 6 and is currently authorized for use.
Use: Treatment of serious symptoms when oxygen can be used and symptoms are not relieved within 30 minutes at 165 fsw (50 msw).
US Navy Recompression Treatment Table 5.
Use: Treatment of pain-only decompression sickness when oxygen can be used and symptoms are relieved within 10 minutes at 60 ft.
US Navy Recompression Treatment Table 5a.
Use: Treatment of gas embolism when oxygen can be used and symptoms are relieved within 15 minutes at 165 fsw (50 msw).
US Navy Recompression Treatment Table 6.
Use: Treatment of pain-only decompression sickness when oxygen can be used and symptoms are not relieved within 10 minutes at 60 fsw (18 msw).
Catalina modification.
The Catalina treatment table is a modification of Treatment Table 6. Oxygen cycles are 20 minutes, and air breaks 5 minutes. The full Catalina Table allows for up to 5 extensions at 60 fsw.
Shorter versions include: 
Tenders breathe oxygen for 60 minutes at 30 fsw. Further treatments may follow after at least 12 hours on air at the surface.
US Navy Recompression Treatment Table 6a.
Use: Treatment of gas embolism when oxygen can be used and symptoms moderate to a major extent within 30 minutes at 165 ft.
At 50msw (absolute pressure 6 bar) an oxygen fraction of 50% will produce a partial pressure of 3 bar, This could be a nitrox, heliox or trimix blend with 50% oxygen.
US Navy Treatment Table 7.
Use: Treatment of non-responding severe gas embolism or life-threatening decompression sickness. It is used when loss of life may result from decompression from 60 fsw. It is not used to treat residual symptoms that do not improve at 60 fsw, or to treat residual pain.
US Navy Treatment Table 8.
Use: Mainly for treating deep uncontrolled ascents when more than 60 minutes of decompression have been omitted.
US Navy Treatment Table 9.
Use: Hyperbaric oxygen treatment as prescribed by Diving Medical Officer for:
US Navy Treatment Table for decompression sickness occurring on saturation dives.
Use: For treatment of decompression sickness manifested as musculoskeletal pains only, during decompression from saturation.
Use: For treatment of serious decompression sickness resulting from upward excursion.
Decompress after treatment according to normal saturation decompression schedule from the treatment depth.
Tektite I and II Treatment and emergency decompression schedule for a 42 to 50 foot saturation dive.
Treatment of Tektite aquanauts after emergency surfacing.
Tektite II Treatment and emergency decompression schedule for the 100 foot saturation dive.
Treatment of Tektite aquanauts after emergency surfacing.
Royal Navy 1943 Recompression Treatment Procedure.
Treatment of any decompression sickness symptoms.
Royal Navy Table 51 - Air Recompression Therapy.
Use: Treatment of pain-only decompression sickness when oxygen is not available and pain is relieved within 10 minutes at or less than 20 msw (667 fsw)
Royal Navy Table 52 - Air Recompression Therapy.
Use: Treatment of pain-only decompression sickness when oxygen is not available and pain is "not" relieved within 10 minutes at or less than 20 msw (66 fsw) but does have relief within 10 minutes at 50 msw (165 fsw).
Royal Navy Table 53 - Air Recompression Therapy.
Use: Treatment of joint pain plus a more serious symptom of decompression sickness when oxygen is not available and symptoms are relieved within 30 minutes at or less than 50 msw (164 fsw)
Royal Navy Table 54 - Air Recompression Therapy.
Use: Treatment of joint pain plus a more serious symptom of decompression sickness when oxygen is available and symptoms are "not" relieved within 30 minutes at or less than 
Royal Navy Table 55 - Air Recompression Therapy.
Use: Treatment of joint pain plus a more serious symptom of decompression sickness when oxygen is not available and symptoms are "not" relieved within 30 minutes at or less than 50msw (164 fsw)
Royal Navy Table 61 - Oxygen Recompression Therapy.
Use: Treatment of pain only decompression sickness when oxygen is available and pain is relieved within 10 minutes or at less than 18 msw (59 fsw), or for serious symptoms where a specialist medical officer is present.
Royal Navy Table 62 - Oxygen Recompression Therapy.
Use: Treatment of pain only decompression sickness when oxygen is available and pain is not relieved within 10 minutes at 18 msw (59 fsw), or for serious symptoms where a specialist medical officer is present.
Royal Navy Table 71 - Modified Air Recompression Table.
Use: Treatment of any decompression symptom if a specialist medical officer is present.
Royal Navy Table 72 - Modified Air Recompression Therapy.
Use: Treatment of any decompression symptom if a specialist medical officer is present. Applicable for multiple recompression of submarine survivors.
RNPL Therapeutic Decompression from a Helium-Oxygen Recompression.
Use: Treatment of decompression sickness occurring during decompression from a Heliox dive.
French Navy Recompression Treatment Table 1 (GERS 1962).
Use: Treatment of mild decompression sickness.
French Navy Recompression Treatment Table 2 (GERS 1962).
Use: Treatment of mild to moderate decompression sickness.
French Navy Recompression Treatment Table 3 (GERS 1962).
Use: Treatment of moderate to severe decompression sickness.
French Navy Recompression Treatment Table 4 (GERS 1962).
Use: Treatment of severe decompression sickness.
French Navy Recompression Treatment Table 4A (GERS 1962).
Use: Treatment of severe decompression sickness.
French Navy Air Recompression Treatment Table (GERS 1964).
Use: Treatment of decompression sickness.
French Navy Air Recompression Treatment Table (GERS 1964).
Use: Treatment of decompression sickness.
French Navy High-Oxygen Recompression Treatment Table (GERS 1964).
Use: Treatment of moderately severe decompression sickness.
French Navy Recompression Treatment Table A (GERS 1968).
Use: Treatment of mild decompression sickness after dives to less than 40 m depth.
French Navy Recompression Treatment Table B (GERS 1968).
Use: Treatment of mild decompression sickness after dives to more than 40 m depth.
French Navy Recompression Treatment Table C (GERS 1968).
Use: Treatment of moderately severe decompression sickness after dives to more than 40m depth or severe decompression sickness after dives shallower than 40m.
French Navy Recompression Treatment Table D (GERS 1968).
Use: Treatment of moderately severe and severe decompression sickness.
French Navy Recompression Treatment Table 1A (GERS 1968).
Use: Treatment of mild decompression sickness after dives to less than 40 m.
French Navy Recompression Treatment Table 2A (GERS 1968).
Use: Treatment of mild decompression sickness after dives to more than 40 m.
French Navy Recompression Treatment Table 3A (GERS 1968).
Use: Treatment of moderate or severe decompression sickness.
Comex Therapeutic Table CX 12.
Use: Treatment of musculoskeletal decompression sickness following normal decompression if symptoms are relieved within 4 minutes or at less than 8 msw.
Comex Therapeutic Table 18C.
Use: Treatment of musculoskeletal decompression sickness following normal or shortened decompression if symptoms are not relieved within 4 minutes at 8 msw, but are relieved within 15 minutes at or less than 18 msw.
Comex Therapeutic Table 18L.
Use: Treatment of musculoskeletal decompression sickness following normal or shortened decompression if symptoms are not relieved within 15 minutes at 18 msw.
Comex Therapeutic Table CX 30.
Use: Treatment of vestibular and general neurological decompression sickness following normal or shortened decompression.
Comex Therapeutic Table CX 30A.
Use: Treatment of musculoskeletal decompression sickness when signs of oxygen toxicity are present.
Comex Therapeutic Table CX 30AL.
Use: Treatment of vestibular and general neurological decompression sickness when signs of oxygen toxicity are present.
Russian Therapeutic Recompression Regimen I.
Use: Treatment of light forms of decompression sickness when the symptoms are completely resolved when reaching a pressure of 29 msw (96 fsw).
Russian Therapeutic Recompression Regimen II.
Use: Treatment of light forms of decompression sickness when the symptoms are completely resolved when reaching a pressure of 49 msw (160 fsw), or if there is a relapse after use of Regimen I.
Russian Therapeutic Recompression Regimen III.
Use: Treatment of moderately severe decompression sickness, or if there is a relapse after use of Regimen II.
Russian Therapeutic Recompression Regimen IV.
Use: Treatment of severe decompression sickness, or if there is a relapse after use of Regimen III.
Russian Therapeutic Recompression Regimen V.
Use: Treatment of very severe decompression sickness, or if there is a relapse after use of Regimen IV.
German Short Air Recompression Treatment Table used during the Rendsburg pedestrian tunnel project.
Use: Treatment of mild decompression sickness where relief occurs within 30 minutes at 30 msw (98 fsw)
German Recompression Treatment Table used during the Rendsburg pedestrian tunnel project.
Use: Treatment of mild decompression sickness where relief does not occur within 30 minutes at 30 msw (98 fsw)
German Recompression Treatment Table used during the Rendsburg pedestrian tunnel project.
Use: Treatment of severe decompression sickness where relief does not occur within 30 minutes at 30 msw (98 fsw)
Oxygen tables designed for monoplace chambers.
Hart monoplace table.
100% oxygen for 30 minutes at 3.0 ATA followed by 60 minutes at 2.5 ATA.
Kindwall's monoplace table.
Indication:
In-water recompression schedules.
In-water recompression (IWR) or underwater oxygen treatment 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 resolve. It is a risky 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.
Six IWR treatment tables have been published in the scientific literature. 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. Richard 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).
Recommended equipment common to these tables includes:
Australian In-water Recompression Table.
The Australian IWR Tables were developed by the Royal Australian Navy 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 Clipperton, 1,300 km from the Mexican coast. 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(a) 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.
Hawaiian In-water Recompression Table.
The Hawaiian IWR table was first described by Farm et al. while studying the diving habits of Hawaii'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 (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 duration of the treatment without any air breaks and is followed by 3 hours of oxygen breathing on the surface.
Royal Navy Table 81 - Emergency therapy in the water.
Use: Emergency in-water recompression when no chamber is available.
"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 DAN'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 attempted 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."
Other tables to be fitted in later.
Lambertsen/Solus Ocean Systems Table 7A.
Used in commercial diving for:
Depth limit 200 fsw for air.