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

First Employee   Aug 05, 2019

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.