Remote Area Diving Issues

IWR and Evacuation, by Matt London

Introduction

Mixed gas cave diving activities are not without their inherent risks but driving on the roads in Thailand is not without inherent risks either! Even though cave diving involves specialized training, equipment, strict rules and procedures designed to minimize any risks to an “acceptable” level, in actuality, a small amount of risk will always remain.

When planning technical dives in remote or isolated areas, such as those where many of the caves in Thailand are found, alternatives to standard or conventional dive emergency protocols and safety procedures must be examined and contemplated seriously and realistically.

The following discussion is an F.A.Q. on diving emergency alternatives for planning dives in remote areas:

Q. What is the most important factor when considering remote diving emergencies?

FIRST AND FOREMOST: A good basic understanding (must be reviewed frequently) of emergency procedures and protocols by all members of the potential diving event. This is perhaps the most important starting point to minimizing risk and maximizing diver safety!

After that responding to decompression illness (DCI) or an air gas embolism (AGE) are right at the top of the list. Always a big concern, a very real risk, somewhat of a reality in technical diving and diving related risks compounded when diving in remote locations. As distance increases so does the risk involved with treatment of a decompression disorder!

Time to Treatment

“Because irreversible injury to nerve tissue can occur within 10 min of the initial hypoxic insult (decompression illness), the preference for immediate and aggressive treatment is obvious.

Unfortunately, the time required for transport of a victim from the dive site to a proper recompression facility is often anywhere from 1 to 10 hours. Therefore the possibility of administering immediate recompression therapy at the accident site by returning the victim to the water should be seriously considered.” [Kizer, 1980]

In-Water Recompression (I.W.R.)

Q. What is IWR?

In water recompression or IWR is the the initiation of immediate recompression therapy at the accident site by means of returning the victim to the water.

Q. Is IWR be a viable treatment for Decompression Sickness?

IWR, if performed correctly, could be a viable option for treating DCI in a remote diving location where no other means of treatment are available. Although IWR should never be viewed as an alternative to proper treatment in a “dry” recompression chamber while breathing 100% 02 at 3.0 atmospheres, IWR should perhaps still be viewed as a means to arrest and possibly eliminate a progressing or otherwise serious case of DCI in cases where conventional treatment is not availible.

NOTE: The authors of this web site do not necessarily endorse IWR, to the contrary, there is no better treatment then breathing pure oxygen in a dry decompression chamber while under the supervision of trained medical personnel.

• Divers need to carefully evaluate all the possible risks and find their solutions before participating in any dive, particularly exploration dives in remote areas..

• Discussions based on clear, concise and realistic emergency protocol between team members, surface support etc. should take place often especially anytime a new team member is initiated.

• Emergency equipment and medical supply stocks should be checked before every dive and vigilantly maintained.

• Emergency Skills should be “rehearsed and reviewed” often particularly as cave dive sites, logistics and personal tend to change from time to time.

I.W.R. in Practice

The following is based on the “Australian Method” of Emergency In-Water Recompression as described by Richard Pile in 1996 (a highly recommended author!). The “Australian Method” is the basis for the Cave Diving Project’s “IWR decompression illness treatment option” as follows:

The “Australian Method”

• This technique may be useful in treating cases of decompression sickness in localities remote from recompression facilities. It may also be of use while suitable transport to such a center is being arranged.

• In planning, it should be realized that the therapy may take up to 3 hours. The risks of cold, immersion and other environmental factors should be balanced against the beneficial effects. The diver must be accompanied by an attendant.

• Equipment – The following equipment is essential before attempting this form of treatment:

• Full face mask with demand valve and surface supply system OR helmet with free flow.
• Adequate supply of 100% oxygen for patient, and air for attendant.
• Wet suit [or dry suit] for thermal protection.
• Shot with at least 10 meters of rope ( a seat or harness may be rigged to the shot).
• Some form of communication system between patient, attendant and surface.

• Method:

• The patient is lowered on the shot rope to 9 meters, breathing 100% oxygen = 1.9 PO2

• Ascent is commenced after 30 minutes in mild cases, or 60 minutes in severe cases, if improvement has occurred. These times may be extended to 60 minutes and 90 minutes respectively if there is no improvement.

• Ascent is at the rate of 1 meter every 12 minutes.

• If symptoms recur remain at depth a further 30 minutes before continuing ascent.

• If oxygen supply is exhausted, return to the surface, rather than breathe air.

• After surfacing, if possible, the patient should be given one hour on oxygen, one hour off, for a further 12 hours.

DEPTH ELAPSED TIME RATE OF ASCENT
(meters) Mild ……………Serious
9 0030-0100………0100-0130
8 0042-0112………0112-0142
7 0054-0124………0124-0154 12 minutes
6 0106-0136………0136-0206 permeter
5 0118-0148………0148-0218
4 0130-0200………0200-0218
3 0142-0212………0212-0242
2 0154-0224………0224-0254
1 0206-0236………0236-0306

from Edmonds et al. (1981), p.558.

Q. Yes, I understand there’s now several recompression chambers available throughout Thailand. Anything other then just getting the victim there quickly that might help the situation?

While while “early treatment of decompression illness (DCI) often results in successful reversal of the symptoms delay in treatment can allow the severity of DCS symptoms to progress” so it’s important to transport the victim as quickly as possible.

DCI Evacuation Protocol

Transport

• Transport directly to the nearest recompression chamber (call ahead during transport) immediately and without delay.

• A complete list of hyperbaric facilities addresses and contact numbers should be posted inside each oxygen and first aid kit i.e. Bangkok, Ko Samui, Phuket.

Oxygen

• The patient (s) should be put on 100% oxygen immediately.

• The anesthetic type mask works best for producing an air tight fit.

• Pure oxygen in the lungs produces the highest possible gradient for off-gassing inert gases.

• Demand valves only!!!

• Continuous flow systems would be considerably less effective for long transport (make sure you have adequate supplies of 02).

• Drowning unconscious divers may require assisted ventilation this can be accomplished with IPPR (intermittent positive pressure respiration).

• An IPPR should be on site.

• After administering oxygen have patient get comfortable and transport (left side down if AGE is suspected).

Fluid Replacement

• Begin re-hydration therapy ASAP.

• Aggressive hydration increases blood intervascular volume, maintains blood pressure and may help in the elimination of inert gases.

• Water works best and avoid glucose, caffeine or alcohol based drinks.

• Remember if hydration can effectively occur during transport the victim (s) will need to urinate.

• Urinary catheter works best, but plastic water bottle will also work for men.

• Anyone trained to institute and monitor an intravenous infusion of saline solution, or a plasma substitute called Dextran (Fructus 1979) should initiate if victim (s) is unable to drink fluids (or urinate).

• Dehydration is a major contributing factor in DCI. Dehydration can also complicate DCI by reducing blood volume causing blood viscosity to thicken and making blood flow less efficient.

Treat for Inflammation

• Intramuscular administration of corticoid drugs, (i.e. Decadron/ Dexamethasone) and aspirin to counter possible platelet aggregation. Immerse (1998).

• NOTE: Paracetamol, moltren, or ibuprofen can be used in absence of Decadron or Dexamethasone during transport.