From the 1998 Workshop:
Pearl divers
After 1989, when the deaths for pearl diving had been reduced to 0-1 per year, attention
became focused on the next major problem, DCS. Information about the value of oxygen
at 9 metres spread by word of mouth, from visiting lecturers.
It started to be used both for decompression and recompression treatment.
Wong11, Nishi10 and Edmonds12 have described the diving schedules and the results,
during the last decade. Of reference to this report is the divers experience with DCS and
its underwater treatment.
During the 4 years, 1988-91, extending over 4 pearl diving seasons, a survey of 10% of subjects
covered a total of 1,834 days dived by these open ocean shell divers. It comprised 11,776 dives,
averaging 6.4 dives per day. The divers were exposed to depths between 10 and 54 metres.(Table 1).
Table 1 - (Omitted as can't format properly)
DCS was the commonest medical disorder recorded (45%). The existence of a DCS diagnosis in the
diving logs was verified by the recorded extra decompression time employed. This involved an
administration or extension of O2 at 9m for 30-45 min. The incidence of DCS from a diving day
increases progressively from: 0.2% at 10-14m depths to 13.6% at 45-54m depths.
Of the 1,834 diver days worked (11,776 dives), there were 56 cases of DCS and 55 were treated
successfully on the UW O2 regime.
By extrapolation to the remainder of the Broome and Darwin fleets, we can presume a DCS case load of about 500 treated underwater on oxygen over those 4 seasons of diving. Only one required
medevac.
Provisos must be noted.
1. All cases occurred at sea, and treatments were usually given within 30 minutes. Occasionally the diver would return to the depth of the dive to complete another "drift" before being treated with oxygen.
2. Except for the diver who required medevac, most divers continued diving on that or the next day without any more problems.
3. We have no idea of how this treatment influences the propensity to dysbaric osteonecrosis.
Like the abalone divers, their pearl divers have modified the treatment regime, but not in the same
manner. Their consistent routine is to employ oxygen for 30 minutes at 9 meters, extendible if any
symptoms persist, and then ascend at a relatively fast rate of 3 metres per minute.
DISCUSSION
The physiological principles on which UW02 is based are well known and not contentious,
although the indications for treatment may be.
It was originally hoped that the UW02 treatment would be sufficient for the management of
minor cases of DCS and so avoid medevac requirements, and to prevent deterioration of the
more severe cases while suitable transport was being arranged. When the regime was applied
early, even in the serious cases, the transport was rarely required.
It is a common observation in recreational divers treatment that improvement continues
throughout the ascent, at 12 minutes per metre. Presumably the resolution of the bubble is more
rapid at this ascent rate than its expansion due to Boyle's Law.
The pearl divers, probably because of their speedy return to pressure and rapid treatment on
oxygen, are able to reduce the duration on oxygen and cope with a faster ascent rate.
Critics of the underwater treatment technique often complain that its success is based on
anecdotal cases. The vast numbers of divers employing it effectively make it more than
anecdotal- and the numbers now exposed safely to shallow (9m or less) oxygen are extreme in
both pearl divers and hyperbaric patients. The critics then often imply great danger citing one or
two patients with symptoms that may be related to oxygen or may be related to the original dive
i.e. genuine anecdotes!
Reports by Pyle and Youngblood31 from the (predominantly) Hawaiian divers using in-water
recompression highlighted both the disadvantages and value of this procedure. Of the 527
cases, 87.7 % got complete resolution, 9.7 % had mild residua and 2.7 % required additional
recompression chamber therapy.
The UW02 recompression treatment is not applicable to all cases, especially when the patient is
unable or unwilling to return to the underwater environment. It is presumably of less value in
the cases where gross decompression staging has been omitted, or where a coagulopathy has
developed. I would be reluctant to administer this regime where the patient has epileptic
convulsions or is unconscious. Others are less conservative.
Pearl divers
After 1989, when the deaths for pearl diving had been reduced to 0-1 per year, attention
became focused on the next major problem, DCS. Information about the value of oxygen
at 9 metres spread by word of mouth, from visiting lecturers.
It started to be used both for decompression and recompression treatment.
Wong11, Nishi10 and Edmonds12 have described the diving schedules and the results,
during the last decade. Of reference to this report is the divers experience with DCS and
its underwater treatment.
During the 4 years, 1988-91, extending over 4 pearl diving seasons, a survey of 10% of subjects
covered a total of 1,834 days dived by these open ocean shell divers. It comprised 11,776 dives,
averaging 6.4 dives per day. The divers were exposed to depths between 10 and 54 metres.(Table 1).
Table 1 - (Omitted as can't format properly)
DCS was the commonest medical disorder recorded (45%). The existence of a DCS diagnosis in the
diving logs was verified by the recorded extra decompression time employed. This involved an
administration or extension of O2 at 9m for 30-45 min. The incidence of DCS from a diving day
increases progressively from: 0.2% at 10-14m depths to 13.6% at 45-54m depths.
Of the 1,834 diver days worked (11,776 dives), there were 56 cases of DCS and 55 were treated
successfully on the UW O2 regime.
By extrapolation to the remainder of the Broome and Darwin fleets, we can presume a DCS case load of about 500 treated underwater on oxygen over those 4 seasons of diving. Only one required
medevac.
Provisos must be noted.
1. All cases occurred at sea, and treatments were usually given within 30 minutes. Occasionally the diver would return to the depth of the dive to complete another "drift" before being treated with oxygen.
2. Except for the diver who required medevac, most divers continued diving on that or the next day without any more problems.
3. We have no idea of how this treatment influences the propensity to dysbaric osteonecrosis.
Like the abalone divers, their pearl divers have modified the treatment regime, but not in the same
manner. Their consistent routine is to employ oxygen for 30 minutes at 9 meters, extendible if any
symptoms persist, and then ascend at a relatively fast rate of 3 metres per minute.
DISCUSSION
The physiological principles on which UW02 is based are well known and not contentious,
although the indications for treatment may be.
It was originally hoped that the UW02 treatment would be sufficient for the management of
minor cases of DCS and so avoid medevac requirements, and to prevent deterioration of the
more severe cases while suitable transport was being arranged. When the regime was applied
early, even in the serious cases, the transport was rarely required.
It is a common observation in recreational divers treatment that improvement continues
throughout the ascent, at 12 minutes per metre. Presumably the resolution of the bubble is more
rapid at this ascent rate than its expansion due to Boyle's Law.
The pearl divers, probably because of their speedy return to pressure and rapid treatment on
oxygen, are able to reduce the duration on oxygen and cope with a faster ascent rate.
Critics of the underwater treatment technique often complain that its success is based on
anecdotal cases. The vast numbers of divers employing it effectively make it more than
anecdotal- and the numbers now exposed safely to shallow (9m or less) oxygen are extreme in
both pearl divers and hyperbaric patients. The critics then often imply great danger citing one or
two patients with symptoms that may be related to oxygen or may be related to the original dive
i.e. genuine anecdotes!
Reports by Pyle and Youngblood31 from the (predominantly) Hawaiian divers using in-water
recompression highlighted both the disadvantages and value of this procedure. Of the 527
cases, 87.7 % got complete resolution, 9.7 % had mild residua and 2.7 % required additional
recompression chamber therapy.
The UW02 recompression treatment is not applicable to all cases, especially when the patient is
unable or unwilling to return to the underwater environment. It is presumably of less value in
the cases where gross decompression staging has been omitted, or where a coagulopathy has
developed. I would be reluctant to administer this regime where the patient has epileptic
convulsions or is unconscious. Others are less conservative.
