Treatment

One should be careful in extrapolating interventions successfully employed in the military and occupational diving setting to recreational diving. For instance, the occupational nature and operational risk for DI in professional diving mandate the availability of on-site recompression; the outcomes of treatment are therefore proportionally good. However, this level of medical support is neither practical nor necessary for typical recreational diving. Importantly, however, a lack of expedient recompression changes the nature of the disorder in need of treatment. With delay to recompression comes a multitude of additional pathophysiological mechanisms that may require more than pressure alone. The importance of oxygen above increased pressure, may therefore be a relevant consideration in these cases. Ultimately answering the various complex questions on appropriate therapy will only be possible after further studies specifically relevant to recreational diving.

Hyperbaric treatment, commenced as soon as possible, using 100% oxygen at pressures not exceeding 2.8 atmospheres absolute (ata), achieves very good results in more than 80% of recreational DI cases. There is no convincing evidence that higher pressures or other breathing mixtures achieve better clinical outcomes in such surface-oriented diving. The administration of adjunctive fluid therapy is usually recommended by diving/hyperbaric medicine specialists in Europe whereas the role of other drugs, such as steroids and anti-coagulants remains controversial.

In 1994, the European Committee for Hyperbaric Medicine (ECHM) organized its first European Consensus Conference, where DI was one of the topics 131. In 1996 a second, more specific Consensus Conference was organized 132, the theme of which was "The Treatment of Decompression Accidents in Recreational Diving". Their recommendations regarding recompression were as follows:

Decompression accidents are true medical emergencies that should receive the benefit of dedicated treatment in specialized centers as soon as possible. A specialized centre is considered a hospital-based recompression facility with permanent and adequately trained medical and paramedical staff.

After immediate stabilization and medical evaluation, the victims of a decompression accident should be immediately directed to the closest specialized centre - (ECHM Type 1 recommendation: strongly recommended).

In water recompression should never be performed as the initial recompression - (ECHM Type 1 recommendation: strongly recommended).

Minor decompression accidents (pain only) can be treated with oxygen recompression tables at 18 meters depth maximum. (Note: this is based on the experience and the good results observed in commercial diving) -(ECHM Type 1 recommendation: strongly recommended).

For more serious decompression accidents (e.g., neurological and vestibular accidents), there are presently two acceptable protocols:

• Oxygen recompression tables at 2.8 ata (with or without extensions)

• Hyperoxygenated breathing mixtures at 4.0 ata (50:50 Heliox or Nitrox as per Comex 30 Table or derivatives)

As for pressures exceeding 4 ata: In lieu of scientific evidence, no specific recommendations can be made at this stage regarding the optimal PiO2 (i.e., the range of 1.26 ata [i.e., Air] to 3.0 ata [i.e., 50:50 Nitrox] at 6 ata) nor on the preferred choice of diluent inert gas. Familiarity, availability and experience may affect decisions, but under no circumstances should the lack of availability of gas mixtures preclude or delay treatment by means of "low pressure oxygen tables" - (ECHM Type 1 recommendation: strongly recommended).

Compression to 6 ata in case of Cerebral Arterial Gas Embolism is optional, with the proviso that this be performed using mixed gas (50:50 or 60:40 Nitrox) and not compressed air and only if the delay to recompression is no more than a few hours - (ECHM Type 3 recommendation: optional). Again there are no data guiding the maximum piO2 nor the maximum delay within which this therapy is still considered appropriate.

In case of severe, persistent clinical signs, during the initial recompression, the continuation of treatment with a therapeutic saturation table may be useful - (ECHM Type 3 recommendation: optional).

All decompression accidents should recorded in a standardized way for the purpose of compiling an epidemiological database.

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