How to Deal with an Unconscious Rebreather Diver?

How to Deal with an Unconscious Rebreather Diver?
By Cedric Verdier
info@cedricverdier.com



The title of this article was originally What to do if a convulsion happens? Based on a lot of discussion, private or on the Rebreatherworld Forum, the protocol being presented here can actually be used for any kind of situation where an unconscious rebreather diver is found underwater.

The main goal of this article is to end up with some guidelines to safely and efficiently deal with an unconscious diver.

Those guidelines are purposely:

• Simple and easy to remember - In a real life emergency the technique is always more complex to perform and more difficult to remember, even if the rescuer practises it on a regular basis.
• Flexible enough to be used in most of the circumstances (dry suit or wet suit, overhead environment or open water, deep Trimix or shallow Nitrox dive, etc) and with all the rebreathers available (back-mounted/OTS CLs, SCR/CCR, FFM, etc).

Remember that the most important factors are:

• The safety of the rescuer like any type of rescue, there is no reasons why a potential fatality should become two fatalities.
• The most life-threatening problem for the victim. In most of the cases, drowning should be considered as the major threat. Hypoxia is also a very important issue. People can recover from DCS or even from AGE, not from complete drowning.

So the most important thing to remember is to bring the victim to the surface safely and as quickly as reasonable. The initial cause of the unconsciousness is not really crucial and the rescuver shouldn't loose a lot of precious time to determine if they are dealing with Hypercapnia, Hypoxia or Hyperoxia.

Hyperoxia is a special case as a convulsion could appear. Susceptibility to a high level of Oxygen varies both between individuals and within the same person from day to day.

A grand mal convulsion generally occurs in three phases:

1. The Tonic phase - a period of body rigidity which may last for up to a minute. It is dangerous to attempt to surface the casualty at this stage because spasm of the glottis and respiratory muscles will result in inadequate exhalation and may therefore provoke pulmonary barotrauma. Fortunately this phase doesn't last more than a minute.
2. The Clonic phase during which the casualty undergoes true convulsions. This can last for widely varying periods of time. Based on some studies and discussions with medical experts (see reference), it looks like the airway is not blocked at this stage.
3. The Post-Ictal phase during which the victim rests and actually resumes breathing. Depending on the circumstances, the victim can 'wake-up' and be confused, disorientated or even combative for quite a long time, or simply stay unconscious. Other convulsions may follow the first one, sooner or later.

So what to do?

• Step 1: Stabilizing the Victim in the Water Column

- If the diver is found unconscious close to the bottom, find a stable position on the bottom or on a shot line.
- If the diver is found unconscious in mid-water or during deco, try to maintain the depth by catching the ascent line.

If the rescuer can attract attention and get some help, a second diver can be very handy to help the rescuer.

- In open water, to send an emergency SMB to make the surface support aware of the situation.
- In a cave, to go through restrictions or simply to take care of the navigation.
- At the surface, to remove the victim's gear and to provide first aid.
- In general, to control buoyancy on the bottom and during the ascent.

• Step 2: Assessing the Situation

The rescuer has to assess the victim, the equipment and the environment in order to determine the best course of action and if the ascent has to be immediate or slightly delayed. In any case this assessment should be quick and shouldn't delay the rescue but make it more efficient. The rescuer has to deal with a high level of stress as time is crucial.

• A. The Victim

- Is it an Oxygen Toxicity Seizure?
In case of a convulsion underwater, the dangerous parth being the Tonic phase that doesn't last very long, the diver's depth has only to be kept constant at the very beginning (a few seconds up to one minute). If drowning is a major concern (as it should be if the rebreather divers doesn't wear a FFM or a neckstrap that efficiently protect their airway), the main priority is to bring the victim as soon as safely possible.

- Is the Victim Breathing?
If there is no obvious sign of breathing (no bubble, no chest movement, no movement of the counterlungs), it is of the utmost importance to bring the victim to surface to administer artificial respiration/CPR.

• B. The Equipment

- Does the Diver wear a FFM or a Neckstrap that Efficiently Protect their Airway?
If it's not the case, even if the diver has still their mouthpiece in place, drowning is a major concern and any delay in the ascent should be avoided.

- Is the Mouthpiece Still in the Mouth?
If not, do not attempt to replace it but ensure that the mouthpiece is switched to the surface position. Try to seal the mouth and ascend immediately.

Note: Opening the mouth to put in a regulator might only achieve water introduction/ drowning. Some rescuers feel confident in attempting to seal a second stage with a breathable mix against the lips in the hope that if breathing resumes air will be inspired instead of water. None of these actions should delay the ascent or compromise the efficiency of the rescue.

- Is there any Water in the Mask?
A partially or completed flooded mask could be a major problem for the victim's airway. If it's the case, try to pinch the nose during ascent.

- Is the Loop Content Safe to Breathe?
This is only a concern if the diver breathes and their airway is protected. The rescuer can check the pO2 readings to make sure that the victim will be able to breathe a safe mix during the ascent.

Hypoxia Its crucial to check the loop content, as the pO2 will drop when ascending to the shallows.

Hyperoxia Flushing the loop with dilutent or switching to an integrated OC second stage (BOV) could be an option to consider (remember that breathing a high O2 content in the loop could also be beneficial on a decompression standpoint). In case of Mixed-gas diving, the OC mix has to breathable all the way up to the surface and the amount of gas in the tank has to be sufficient (and the valve open).

Hypercapnia Without a proper scrubber monitor, it will be difficult for the rescuer to assess the CO2 level in the loop and it's not a major issue anyway. A dilutent flush will help in any case, as it could also help in case of partial loop flood.

Note: To efficiently flush the loop on most of the units, the rescuer has to open the OPV first.

• C. The Diving Environment

- Is there any Physical Problem that could Delay the Ascent?
A strong current could make the rescuer consider swimming to an ascent line rather than drifting far from the boat.
An overhead environment (cave, ice, wreck penetration) could delay the ascent as the rescuer will have to swim to the exit point.

- Is there any Physiological Concern that could Delay the Ascent?
If a breathing victim with a properly protected airway (FFM, neckstrap) has a significant decompression obligation, the rescuer has to consider the possibility of performing the required stops to minimize the risks of DCS.

If the victim doesn't breathe or doesn't have a properly protected airwat, the ascent to the surface should be immediate. Nevertheless, the rescuer could have a significant decompression obligation as well. In this case, three main options are available:

1. Ascending with the victim at the surface, provide 1st aid or hand over the victim to the surface support, then eventually follow a missed deco procedure.
2. Handing the victim over to another diver with no/less decompression obligation.
3. Sending the victim to the surface on their own, hoping that the surface support will be efficient and fast enough

Note: This is a personal decision, based on a lot of factors that have to quickly considered by a highly stressed rescuer.
- The apparent state of the victim (not breathing since a very long time, etc).
- The amount of decompression obligation and the perceived risk of DCS.
- The accepted risk (that could depend on the relationship with the victim).
- The efficiency and the availability of the surface support.
- The surface condition (rough sea where the victim will not be seen, etc).

• Step 3: Ascending to the Surface

• A. Opening the Airway

Ensure that the victim's airway is open by keeping the neck slightly extended.

• B. Controlling the Ascent

It's often very difficult to keep control on the buoyancy of 2 divers at the same time, particularly in the shallows:
- Slowly inflate the victim's BC to start ascending.
- Open the victim's loop OPV (and the drysuit purge if appropriate).
- Control the victim's BCD purge.
- Control the rescuer's own buoyancy.

Note: In case of a malfunctioning unit (leaking solenoid, ADV, manual injector, BCD inflator, etc), it may be difficult for the rescuer to quickly find out if there is a leak, where it comes from and how to stop it. The rescuer has to be awate that the rescue could end up in an uncontrolled ascent.

• C. Establishing Positive Buoyancy at the Surface

If the loop is not flooded, simply fully inflate the victim's BC should provide enough buoyancy to maintain the diver at the surface. Make sure t hat the DSV is closed when removed from the mouth.
Depending on the equipment or if the loop is flooded, it may be necessary to release some weight or accessories (canister light, sling tank, etc).

• Step 4: Providing First Aid

This means first care for the victim AND the resucer:
- Call for help. If no help is available, it may be necessary for the rescuer to stop for a few seconds to keep the stress level reasonable and assess the victim and the resources available at the surface.
- Ensure the victim is breathing or initiate artificial ventilation (as taught in all the basic Rescue Diver courses).
- Hand over the victim to the surface support or swim to the nearest platform available (boat, shore, etc) in order to provide better care (CPR/ 1st Aid/ O2).
- Arrange for evacuation (nearest chamber/ diving physician).
- The rescuer may perform missed deco procedures if appropiate (without delaying evacuation).

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This document was written with the preciousl help of Dr Mike Gadd, Jon "Gibbon" Swarbrick, Cathy Riley and other members of the Rebreather World Forum (amongst them: Sutty, Deepwreck, ScubaDadMiami, Janos, Genesis, UKSteve, jhaaja, mdemon, jasondrake, bobmaggi, dteubner, silent running, Neil Holden, Bruce Partridge, silentscuba, Simon Mitchell, Andrew "Gasman". I hope I don't forget anybody). It doesn't necessarily reflect the opinions of all these people, the rebreather diving community or the medical community.

This document is only a guideline to help developing a widely accepted standard for rebreather resuce. Such a standard doesn't exist in the sport diving industry and may never exist


References

• The Prevention and Management of Divign Accidents (Revised October 1997) - Royal Navy INM Report No. R97066
• US Navy Diving (Chapter 17 and 17b) - USN
• Commercial Diving Operations - OSHA Occupational Safety and Health Administration
• Extreme Survival: A Deep Technical Diving Accident - Trytko, B. and Mitchell, S.; South Pacific Underwater Medicine Society Journal
• Proceedings of Rebreather Forum 2.0 - Michael Menduno, DSAT
• Oxygen Toxicity Protocol - Scott Hunsucker, WKPP
• Oxygen and the Diver - Donald KM, England
• A Statistical Anaylsis of Recent NEDU Single-depth Human Exposures to 100-percent Oxygen at Pressure - Harabin, A.L., Survanshi, S.S. and Bethesda, M.D.; Naval Medical Research Institute
• Glottal Patency During Experimental Cortical Seizures in Piglets - Leaming; Academic Emergency Medicine
• Current Thoughts on Mechanisms of Hyperoxic Seizures - Johnny E Brian Jnr, University of Iowa Hospitals and Clinics