​Treatment of Decompression Illness in the Faraway. By: Greg Barefoot

​Treatment of Decompression Illness in the Faraway

Imagine that you are on a dive vacation off the coast of the Solomon Islands, when you notice
your right arm becoming progressively weaker by the minute. The symptoms occurred
approximately 15 minutes after surfacing from an otherwise uneventful dive that was made
using EANx 32. What could be wrong? If you thought decompression illness (DCI), then you
would be correct. What’s next? Our training tells us, to place the patient on 100% oxygen and
prepare for evacuation to the closest facility that could arrange for recompression. Did I mention
that the closest hyperbaric chamber is 1500 miles away and only accessible via aircraft? What
now?

The urge for exploration and discovery has led many divers to obtain additional education in
technical diving to expand the depths that can be explored. Along the same lines, divers are
traveling to more remote locations that may take several days to reach and therefore will take a
day or two of travel to evacuate. The combination of deeper, longer dive profiles coupled with a
remote setting, can increase the risk of decompression sickness and its long-term effects.

We know from our open water training that the biggest threat to a diver’s health comes from
breathing inert gas (nitrogen) at depth. Decompression illness occurs when the inert gas causes
injury to the diver. It can either be from pulmonary over-inflation syndrome, i.e. arterial gas
embolism, or decompression sickness, which is when nitrogen bubbles form in supersaturated
tissues. These bubbles effect the tissue where they are located by mechanical, embolic or
biochemical interaction.

It is well recognized that recompression is the treatment for decompression sickness since the
U.S. Navy recommended it in the early 1900’s. Recompression in a chamber while breathing
100% oxygen is similar to being at 2.8 atmospheres absolute (60 feet of seawater).
Recompression serves to compress bubble size and increase the diffusion of oxygen into the
cells and nitrogen out. Additionally, increased oxygen mitigates inflammation that occurs when
the body recognizes a bubble as being a “foreign invader”.

The effectiveness of treatment is tied to the time from initial onset of symptoms to the initiation
of treatment. We also know that 97% of symptoms will be relieved if a diver with DCI gets
treated within the first 6 hours of symptom onset. This drops down to the mid-seventies if the
diver gets treated later than 6 hours. When the diver is in a remote location where a
recompression chamber isn’t nearby, timely treatment can be difficult.

In water recompression with 100% oxygen to treat decompression illness has emerged as an
alternative to prolonged evacuation to a recompression chamber. This involves resubmerging a
diver with decompression illness back into the water, which effectively recompresses the diver,

in an attempt to reduce or eliminate symptoms. Even though it has been used as early at 1924,
the diving medical community has not widely accepted its utility. The negative stance likely is
related to the potential complications. The list includes: drowning, oxygen toxicity, worsening of
decompression sickness due to additional ongasing, hypothermia, and dangerous marine life.

These risks are mitigated by using 100% oxygen to prevent additional ongasing as well as using
a full face mask (FFM) to prevent drowning in the event the diver becomes unconscious.
Additionally, appropriate thermal protection can be used if the decompression time is long.
Oxygen toxicity is also mitigated by using the FFM or gag strap and keeping the maximum
depth to 20 fsw (1.6 ATA) as well as having the ability to provide and air break.

There are also contraindications to placing a diver back into the water. They include: cardiac
arrest, airway problems, severe rapid breathing, shock/clinical instability, vertigo, altered mental
status and coughing up blood. Some relative contraindications are: hypothermia, anxiety,
isolated hearing loss and lack of diver support or training.

There are multiple protocols that are available, all of which involve return to the water with either
a gag strap or FFM, and an adequate volume of oxygen, a stable platform, and a tender with a
tether. The tables suggest depths from 20-30 fsw breathing 100% oxygen (1.6 ATA- 1.9 ATA).
They require a certain time at that depth with a slow decompression on 100% oxygen until the
surface is reached. Even if symptoms resolve, most tables recommend follow up evacuation to
the recompression chamber.

With the increase in popularity of diving in general and technical diving in particular, along with
the ability to travel to remote locations, there is an increased risk of decompression illness.
When an event occurs, the diver has two choices: surface oxygen and evacuation with the
potential to delay recompression or reentry into the water for recompression. When a team has
adequate equipment and training, in water recompression gives one the peace of mind, knowing
that they have the skills to mitigate a decompression illness event in faraway places.