Hi graywhale,
By and large, IWR is not recomended except as a very last resort.
Here's an extended treatment of the topic I wrote for Undercurrent:
In-Water Recompression
-- the ignored emergency treatment
Youve sustained DCS hit in a
remote location, hours by air from
the nearest hyperbaric chamber. It
could be serious. The air ambulance
cannot fly due to weather, and even
if it could, its uncertain if the
chamber is operational. What to do?
Dont be surprised if your captain
suggests sending you back down.
While in-water recompression might
sound like folk medicine, it is a valid
emergency technique when performed
under the direction of
someone properly trained.
In-water recompression (IWR),
not to be confused with reentering
the water to complete a missed deco
obligation, is a legitimate emergency
substitute for chamber recompression.
It emulates hyperbaric treatment
by taking the bent diver back
to depth, while he breathes high
concentrations of O2. Depending
upon the method used, he may stay
down as long as ninety minutes at
thirty feet (though some methods go
deeper and total time is longer).
Of course, the advent of IWR
preceded the hyperbaric chamber.
When a hardscrabble diver realized he
could reduce surface pain by going
back to depth, IWR got a foothold. It
was possibly first used by bent sponge
divers off Key West in the late 1800s,
but it may have evolved independently
wherever there were divers. Hawaiian
black coral divers and Australian pearl
divers returned to depth breathing
compressed air. As oxygen became
available, treatment improved
considerably, though compressed air
is still used but not advisedly
when oxygen is unavailable.
Four IWR protocols have been
developed to be applied after a diver
experiences the first DCS symptoms.
Commonly called the Australian, U.S.
Navy, Hawaiian, and Pyle methods,
each differs in submersion depth,
time and ascent requirements. Each
requires its own equipment, personnel
knowledgeable in IWR, skilled
tenders and adequate pure O2 or
other gas. All have plenty of success
stories, as the cases we cite later will
show.
Not surprisingly, major recreational
dive training agencies are
circumspect about IWR. Since it is not
accepted as an appropriate technique,
the lawyers of an injured diver at
least in America might have a field
day. PADI Educational Consultant,
Leroy Wickham told Undercurrent that
they do not teach IWR, nor would
they recommend it, except under
extraordinary circumstances and then
only by qualified and properly
equipped personnel. Several technical
agencies, IANTD and TDI among
them, touch on IWR in trimix classes,
and the entire procedure for the
Australian variant is published in
IANTDs Technical Diver Encyclopedia.
IANTD founder Tom Mount told
Undercurrent that IANTD does not yet
teach IWR because of its lack of broad
acceptance. He includes a caveat that
IWR is only to be done by qualified
and properly equipped individuals in
remote areas where a chamber is not
available. When pressed for an
example of such a location, he named
Bikini, in the North Pacific, where
chamber treatment could be 36 hours
away. Fascinatingly, he mentioned
that he had directed IWR on about 15
divers over the years, including his
wife, during a trip to Roatan before a
chamber was available there. He
reported a startling 100 percent
success rate.
Dive medicine organizations note
that fatigue, cold, panic, seasickness
or an exhausted gas supply, can result
in incomplete treatment, worsening
of the DCS and possible O2-induced
convulsions and hypothermia. Joel
Dovenbarger, VP of Medical Services
at DAN, told Undercurrent that IWR
should only be considered in remote
areas where conventional and proven
methods are unavailable, and where
there are trained personnel and
logistical support.
Despite warnings, the sobering
reality is that when Type II hits with
serious vascular obstruction, irreversible
brain damage can occur after 7
minutes, irreversible spinal cord
damage after 15 minutes and lung
damage after 10-20 minutes. In
addition, research has consistently
shown that the sooner DCS is treated,
the more salubrious the outcome.
So, IWR has its champions.
Veteran technical diving expert Bret
Gilliam has knowledgeably written on
the topic. Richard Pyle, a diveracademic
at Bishop Museum in
Honolulu, is a vigorous champion.
Another solid supporter is Dr. Ann
Kristovich, Women Divers Hall of
Fame member and co-leader of
Proyecto De Buceo Espeleologico
Mexico Y America Central. She holds
that if travel time to a recompression
chamber would take longer than 30
minutes, then she would use IWR.
Australian Dr. Carl Edmonds told
participants at an in-water recompression
workshop that if youve got a
three-hour gap between the patient
getting symptoms and getting a
MEDIVAC going, then you might as
well use ... underwater (recompression)
immediately.
There is a strong theoretical basis
to speculate that the procedure
could be beneficial if applied
correctly. It should reduce bubble
growth, due to both increased
pressure and the washout of nitrogen
by high blood levels of O2. Additionally,
the increased PO2 from breathing
pure oxygen could mitigate tissue
hypoxia secondary to gas embolization.
The most popular method, the
Australian procedure, mandates
continuous breathing of 100 percent
oxygen at a depth of 30 feet for 30
minutes for mild symptoms, up to 90
minutes for severe ones. Ascent rate
is not to exceed 1 foot per 4 minutes,
and inspiration of pure O2 is to
continue for 12 hours.
The Hawaiian method, reasoning
that increasing pressure provides
decreasing bubble size, directs a
spike on air to 30 feet deeper than
the depth at which symptoms resolve,
but not more than 165 feet, for 10
minutes. The diver then ascends to
30 feet and breathes surface supplied
oxygen for prolonged periods.
The U.S. Navy method requires
substantial amounts of pure O2,
and recommends using a 100
percent O2 rebreather. It directs
descent to 30 feet for 30 minutes for
Type I DCS and 90 minutes for Type
II, followed by an ascent completed
in two 60-minute segments, one at 20
feet and a second at 10 feet. After
surfacing, pure oxygen is to be
inspired for 3 hours. The Navy
recommends IWR when a hyperbaric
facility is more than 12 hours away.
Richard Pyle has developed the
latest method. Based on research, but
not empirical evidence none of
the models are his method
administers 100 percent oxygen at
the surface for 10 minutes, during
which they assess the progression of
symptoms. If IWR is appropriate, the
diver, with a tender, is lowered to 25
feet breathing 100 percent oxygen
for 10 minutes. If symptoms resolve
after 10 minutes, the depth is
maintained and pure O2 continues
for 90 minutes, interspersed with 5-
minute periods breathing air or EAN
every 20 minutes. Should symptoms
persist, more complex procedures at
. . . he had directed inwater
recompression on
about 15 divers over the
years, including his wife,
during a trip to Roatan
before a chamber was
available there. He
reported a startling 100
percent success rate.
Pyle got interested in research
after he himself got bent. He told the
in-water recompression workshop
that I was 19 and immortal. I did
some stupid dives ... [afterwards] I
was having rapidly progressing
quadriplegia. I was the only one on
the boat for 10 minutes before I
could hear my buddys bubbles. I
hobbled over to the side and buddy
breathed with him for all of 7
minutes at 10 feet on air and
emerged. I could not detect any
symptoms at all ... they remained
undetected for 20 minutes, long
enough for me to drive the boat back
to a dive shop, alert them, get some
more tanks, and have them get the
recompression chamber operable.
Pyle said his legs were not coordinated
and he was falling down, but
after four more hours of breathing
air at 20 feet, then chamber treatment,
he had no more ill effects.
Data supporting IWR is like Pyles,
that lacks scientific rigor, but is
nevertheless impressive. The results
cut across a hodgepodge of divers,
variants and gases, but meta-analysis
does suggest the procedure works.
An overwhelming majority of bent
divers have come out of IWR either
asymptomatic or improved, with only
a fraction being worsened or having
an ambiguous result. This is especially
provocative given that much of
the reported IWR was done using
compressed air rather than the
recommended 100 percent O2.
Here are a few interesting cases, compiled
by Pyle:
In the Central Pacific, a diver had
partially completed his decompression
following 15 minutes at 200 feet,
when he saw a very large and
inquisitive tiger shark rising above
and passing between him and the
boat, he decided to abort decompression.
After a rapid ascent from 40
feet, he hauled himself over the bow
of the 17-foot Boston Whaler
(without removing his gear) and
instructed his startled companion to
haul up the anchor and drive the
boat rapidly to shallower water. By
the time they re-anchored, the diver
had increased pain in his left
shoulder. He reentered the water
and completed his decompression,
emerging asymptomatic.
After ascending from his second
10-minute dive to 190 feet, a Hawaiian
diver followed the decompression
ceilings suggested by his dive
computer. As he neared the end of
the schedule, he suddenly noticed
weakness and incoordination in both
arms, and numbness in his right leg.
He immediately descended to 80 feet
where, after three minutes, the
symptoms disappeared. After eight
minutes at 80 feet, he slowly ascended
(his companion supplied
him with fresh air tanks) over 50
minutes to 15 feet. He remained at
this depth until his computer had
"cleared." He felt tired after surfacing,
but was otherwise asymptomatic.
"In cases where DCI results from
gross omission of required decompression,
divers may anticipate the
probable consequences, and return
immediately to depth as soon as
possible to complete the required
decompression, " says Pyle. After a
second dive to (100 ft), this Australian
diver omitted decompression
due to an intimidating tiger shark.
Within minutes of surfacing, he
developed back pain, progressively
increasing incoordination, and
partial leg paralysis. After two
unsuccessful attempts at air IWR, he
was transported to a hospital, 100
miles away, 36 hours after the onset
of symptoms.
Due to adverse weather, they
could not transport him to the
recompression chamber, 2,000 miles
away, for an additional 12 hours. By
this time, he was unable to walk and
had cerebral symptoms. They
returned him to the water to 27 feet,
where he breathed 100 percent
oxygen for 2 hours, then decompressed
at 3 feet every 12 minutes
(the Australian Method). Except for
small areas of sensitivity on both legs,
other symptoms had disappeared.
Carl Edmonds reported on a case
that occurred in the Solomon
Islands. At the time, the nearest
recompression chamber was 2,200
miles away and prompt air transport
was unavailable. Fifteen minutes after
a 20-minute dive to 120 feet, and 8
minutes of decompression, a diver
developed respiratory distress, then
numbness and partial paralysis,
severe headaches, involuntary
spasms, clouding of consciousness,
muscular pains and weakness, pains
in both knees and abdominal
cramps. No significant improvement
occurred after 3 hours of surfacebreathing
oxygen, so they returned
her to the water, breathing 100
percent oxygen at 30 feet. Her
condition was much improved after
the first 15 minutes, and after an
hour she was asymptomatic, with no
recurrence of symptoms.
Shortly after a third dive to 120-
160 feet, a Hawaiian diver developed
uncontrollable movements of the
muscles of his legs. Within a few
minutes, he became numb from the
nipple-line down and unable to
move his legs. He could hold a
regulator in his mouth, so a full
scuba tank was strapped to his back
and they rolled him into the water to
a waiting tender diver. The tender
verified that the victim could
breathe, and dragged him down to -
35 feet. When the symptoms did not
regress, the victim was pulled deeper.
At 50 feet, he regained control of his
legs and indicated that he was feeling
much better. They later supplied him
with an additional scuba tank,
ascended to 25 feet for a period of
time and then finished his second
tank at 15 feet. Except for feeling a
little tired that evening, he regained
full strength in his arms and legs and
remained asymptomatic.
Although most of the reported
attempts at IWR have used only air --
and they have been successful -- the
practice is discouraged due to the
risks of additional nitrogen loading.
So, while IWR obviously requires
much further study and adjustment,
it may have a promising future under
the unique set of circumstances for
which it is designed. After all,
breathing oxygen at depth is just what
a hyperbaric chamber is all about.
The day may come when its an
accepted procedure to treat divers,
and the training and medical
agencies will open the door and let it
come out of the closet. But dont
expect that anytime soon. As Richard
Overlock, MD, told the recompression
workshop, there is such a
horrendous bias against the concept
of in-water recompression that
nobody wants to admit they did it.
Getting hard data will be a long time
coming.
In addition to interviews, much of the
material in this article comes from two
sources: 1.) In-Water Recompression as an
Emergency Field Treatment of Decompression
Illness, by Richard L. Pyle and David A.
Youngblood, from the Journal of the South
Pacific Underwater Medical Society, 1997. 2.) In
Water Recompression, The Forty Eight
Workshops of the Undersea and Hyperbaric
Medical Society, published September 1999.
This 108-page paperbound publication,
which contains much fuller discussions of all
the methods and the problems, and
commentary from conference participants, is
available for $22.50 from the Undersea and
Hyperbaric Medical Society, 10531 Metropolitan
Ave, Kensington, MD 20895."
Regards,
DocVikingo
