When treating Decompression Illness in remote locations, patient selection is critical. Due to limited resources, it may not always be practical to treat every patient with signs and symptoms of decompression sickness (DCS) with definitive therapy such as portable hyperbaric oxygen (PHBO) chambers or in-water recompression (IWR.)  A three-tiered triage system is effective when deciding which patients would most benefit from recompression versus conservative management. Tier 1 patients have mild disease, Tier 2 patients have more moderate symptoms, and Tier 3 patients have life-threatening DCI.
Patients with mild symptoms, including mild joint pain or rash consistent with “skin bends,” are very common. Because of the benign nature of Tier 1 patients, it is reasonable to manage these cases conservatively by administering 100 percent surface oxygen, intravenous fluids and oral nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen. More definitive therapy may not be required as the natural progression in these cases is typically benign and self-limiting, but patients must be carefully monitored for progressive signs or symptoms with serial neurologic exams.

Tier 3 patients are those with life-threatening DCI, either severe Type II spinal cord DCS, cardiovascular DCS or arterial gas embolism (AGE) with altered mental status or cardiac arrest. When patients are this sick, advanced cardiac life support takes precedence over hyperbaric therapy. It is unsafe to go back in the water for a trial of IWR and patients are typically too sick to be put in a small portable hyperbaric chamber where team members would be unable to intervene without decompressing the chamber.

Tier 2 patients are the best candidates for either IWR or PHBO therapy. Typically, these patients have moderate to severe Type I DCS including significant joint pain and rash. In contrast to Tier 3 patients, Tier 2 patients are generally able to actively participate in their own care: They’re awake, oriented, able to maintain their own airways and spontaneously breathing. Most important, they must be willing and able to either get back into the water with the appropriate IWR staff and equipment or complete a modified treatment table in a portable chamber.

Portable Hyperbaric oxygen therapy, or PHBO, is the use of a hyperbaric chamber able to deliver at least 2.0 ATA of 100% oxygen in an easily transportable package.   This is in contrast to the majority of portable mild hyperbaric chambers available on the internet, as most of these are soft sided and can only achieve approximately 1.3 ATA and frequently employ compressed air instead of oxygen.  There are several options on the market, the best known being the Hyperlite chamber from SOS/Hyperlite company in the UK.  Their design is essentially a hyperbaric stretcher that has been extensively used by various militaries for transporting DCI patients under pressure from the site to a more stable location.  It has also been used in civilian applications for programs that require some form of safety net while diving in remote locations.  While rather small and claustrophobic, the chamber has an excellent safety record, collapses down into two hard plastic transport cases and can be shipped anywhere in the world along with the rest of the dive gear.  Some training is required to learn how to set up and use the chamber, and its use should only be done by those who are very familiar with hyperbaric chamber operations.  Another drawback is its cost, somewhere north of $50,000 USD with options.

The second option is the use of in-water recompression or IWR.  This method has been rather controversial over the years, and its detractors feel the risks of treatment outweigh the benefits.  But, done with proper training, IWR has been used successfully in the past to treat DCI in remote locations.  The concept involves breathing compressed oxygen at varying depths, basically going back in the water and attempting what some would consider a completion of a blown deco stop.   The equipment required includes facemasks with comm equipment, surface supply oxygen, and a deco stage or trapeze.  Depths underwater vary, but to achieve maximum benefit while minimizing risk depths greater than 9 meters but under 15 meters should be employed.  The availability of 100% surface supplied oxygen is important, but 100% oxygen in an open circuit tank with the ability to gas-switch underwater to a mixed gas (air or nitrox) will do in a pinch.  Treatment time is typically less than a standard U.S. Navy Treatment Table Six, which is 240 minutes.  Instead of exposing the diver to the risk of seizure at depth or hypothermia, it is better to do more frequent but shorter treatments, typically three to five treatments in a 24-hour period, perhaps about 90 to 120 minutes each.  While the patient is on the surface, IV fluids and 100% oxygen should be continued.  It becomes clear that IWR is not to be undertaken lightly and requires significant training, but in the right hands can be used as a supplement to definitive hyperbaric therapy and the equipment is significantly less expensive than PHBO chambers and is much more easily transported.

Regardless of patient selection, treatment of DCS in remote locations with either IWR or PHBO chambers requires significant training, equipment and experience. All patients should receive 100 percent oxygen, intravenous fluids and possibly NSAID therapy. Those who have more significant disease should be considered for recompression therapy. The logistical and financial difficulties associated with both IWR and PHBO can be challenging but are not insurmountable.

Matthew S. Partrick, M.D.

Medical Director, Institute for Diving Medicine

Southern Ocean Medical Center

Manahawkin, NJ USA

drpartrick@scubadivingmedicine.com

www.scubadivingmedicine.com

Photo: Wayne Brown