DIRrebreather Open Distribution Page 1 Open public Unconscious Recreational Rebreather Diver and Rescue Techniques CEDRIC VERDIER, DAVID R. LEE, Dr HOWARD SCORF Verdier C., Lee D.R., Scorf H. – 2008 – Unconscious Rebreather Diver and Rescue Techniques – Various techniques have been designed and tried to rescue an unconscious recreational rebreather diver who passed out underwater or at the surface. A one-year study done by the authors has allowed fine-tuning some techniques to increase the chances of survival. Keywords: rebreather, unconsciousness, blackout, rescue, hyperoxia, hypoxia, hypercapnia • Any kind of recreational diving equipment - dry suit or wet suit, Full- Introduction Face Mask (FFM) or usual half-mask. • Any kind of environment - open water, There is at the moment no guideline and flooded cave, ice, wreck penetration. no protocol for the proper rescue of an • Any depth and breathing gas - Deep unconscious recreational rebreather diver Trimix dive with long decompression at the surface or underwater. Protocols obligation, shallow no-decompression exist in military or commercial diving Nitrox dive. contexts but cannot be applied in extenso • Any kind of rebreather – back- by the recreational rebreather diving mounted or Over-the-Shoulder (OTS) community (1) (2) (3). counterlungs, Semi-Closed (SCR) and Closed Circuit Rebreathers (CCR), The authors have studied in details 32 chest, back and side-mounted fatalities that occurred in the past few rebreathers, with or without Bailout years in the rebreather diving community Valve (BOV). (4) (5). They have also be witness of or directly involved in 3 cases of rebreather In the study cited in reference, one of the diver blackout that ended in a positive most important problems that has been outcome. They were also instrumental in noticed was the lack of priority during the the testing phase of rescue techniques rescue. In a recent rebreather fatality taught to 20 rebreather divers with no where the victim died and the rescuer was previous experience in rescue techniques severely bent (severe symptoms of (6). neurological decompression sickness), it has been emphasized that the most Based on this study, a lot of important important factors of a rescue are: considerations have been noticed, 1. The safety of the rescuer (like in any emphasizing the lack of rescue training for type of rescue, there is no reason why rebreather divers. This training should a potential fatality should end up in emphasize: two fatalities) (7). 1. Simple and easy to remember 2. The most life-threatening problem for techniques. In a real life emergency the the victim. In most of the cases, technique is always more complex to drowning should be considered as the perform and more difficult to remember, major threat. Hypoxia is also a very even if the rescuer practises it on a regular important issue. People can recover basis. Because of the inherent task-load from decompression sickness (DCS) experienced by any rebreather diver, a or even from Arterial Gas Embolism successful rescue tends to be more rare (AGE), not from complete drowning. In than its OC counterpart. most situations, the most appropriate protocol is to bring the victim to the 2. A protocol that is flexible enough to be surface safely and as quickly as used in most of the circumstances: reasonable (3). This document is the property of DIRrebreather and is released for Open Distribution, subject to no modification being made and the document being reproduced in full. DIRrebreather Open Distribution Page 2 Open public Cause of unconsciousness underwater medical experts tend to show that the airway is not blocked at this stage. The reasons why people pass out 3. The ‘Post-Ictal’ phase during which the underwater can be extremely various and victim rests and actually resumes complex. A large array of medical breathing. Depending on the conditions can trigger unconsciousness at circumstances, the victim can “wake-up” various levels of exertion and in various and be confused, disoriented or even circumstances underwater or at the combative for quite a long time, or simply surface. These medical conditions should stay unconscious. Other convulsions may be screened and spotted during a fitness- follow the first one, sooner or later (14). to-dive medical exam (8). However some of them can stay undetected even by diving medicine experts. Protocols Causes of unconsciousness can also result from diving-related problems such 1. Stabilizing the victim in the water as (9): column. - Cold (sudden or long exposure). It has been shown during a few rescue - Marine Life Injury (bite, sting, attempts that it might be extremely difficult injection of toxin). to stop a free-falling unconscious - Vomiting (seasickness, vestibular rebreather diver in mid-water (15). disorders, etc). • If the diver is found unconscious - Decompression Sickness and close to the bottom, the rescuer Pulmonary Barotrauma. should find a stable position on - Inert Gas Narcosis. the bottom. - Carbon Monoxide Toxicity. • If the diver is found unconscious in mid-water or during deco, the Some rebreather-specific problems can easiest technique used during the also trigger physiological problems at the study has been to maintain the origin of a blackout (10) (11) (12): depth by grabing the ascent line. - Hypercapnia (excess of CO2). - Hypoxia (lack of O2). Out of 57 rescue attempts performed - Hyperoxia (excess of O2) during the evaluation phase of these protocols, all the rescuers have obtained The initial cause of the unconsciousness is very promising outcomes every time not really crucial and the rescuer shouldn’t another diver, regardless of their level of loose a lot of precious time to determine if training and experience, has helped them they are dealing with Hypercapnia, (6). So it’s strongly recommended for the Hypoxia or Hyperoxia. However Hyperoxia rescuer to try by all means to attract is a case on its own, as a convulsion could attention and get some help to: appear. Susceptibility to a high level of - Send an emergency SMB to make the oxygen varies both between individuals surface support aware of the situation (in and within the same person from day to open water). day and the occurrence of convulsions - Go through restrictions or simply to take might create additional problems and care of the navigation (in a cave). delays for the rescuer (13). - Remove the victim’s gear and to provide first aid (at the surface). A grand mal convulsion generally occurs - Control buoyancy and body position on in three phases: the bottom and during the ascent. 1. The ‘Tonic’ phase - a period of body rigidity. It is dangerous to attempt to surface the casualty at this stage because 2. Assessing the situation spasm of the glottis and respiratory muscles will result in inadequate The rescuer has to assess the victim, the exhalation and may therefore provoke equipment and the environment in order to pulmonary barotrauma. Fortunately this determine the best course of action and if phase doesn’t last more than a minute. the ascent has to be immediate or slightly 2. The ‘Clonic’ phase during which the delayed. In any case this assessment casualty undergoes true convulsions. This should be quick and shouldn’t delay the can last for widely varying periods of time. rescue but make it more efficient. The Some studies and discussions with rescuer has to deal with a high level of This document is the property of DIRrebreather and is released for Open Distribution, subject to no modification being made and the document being reproduced in full. DIRrebreather Open Distribution Page 3 Open public stress, time pressure being quite Hypoxia: checking the loop content during important. The following elements have to the ascent is crucial, as the pO2 will drop be quickly assessed: when ascending to the shallows. - The victim Hyperoxia: Flushing the loop with diluent - The equipment or switching to a Bailout valve (BOV) could - The environment be an option. However one should also consider that breathing a high O2 mix in 2.1 The victim the loop could be beneficial on a Is it an oxygen toxicity seizure? In case of decompression standpoint. In case of a convulsion underwater, the dangerous Mixed-gas diving, the open-circuit (OC) part being the Tonic phase, the victim’s mix has to be breathable all the way up to depth has only to be kept constant at the the surface and the amount of gas in the very beginning (a few seconds up to one tank has to be sufficient. minute) (16). If the rebreather diver Hypercapnia: Without a proper scrubber doesn’t wear a FFM or a neck-strap that monitor, it will be difficult for the rescuer to efficiently protects their airway, drowning assess the CO2 level in the loop but it’s is a major concern. Therefore the main not a major issue anyway. A diluent flush priority is to bring the victim to the surface will help in any case, as it could also help as soon as safely possible. in case of a partial loop flood (19). Remember that, in order to efficiently flush Is the victim breathing? If there is no the loop on most of the units, the rescuer obvious sign of breathing (no bubble, no has to open the overpressure valve (OPV) chest movement, no movement of the first. counterlungs), it is of the utmost importance to bring the victim to surface to 2.3 The diving environment administer artificial respiration/Cardio- Is there any physical problem that could Pulmonary Resuscitation (CPR) (17). delay the ascent? An overhead environment (cave, ice, wreck penetration) 2.2 The equipment could delay the ascent as the rescuer will Does the diver wear a FFM or a neck- have to swim to the exit point. strap that efficiently protect their airway? If A strong current in open water could also it’s not the case, even if the diver has still make the rescuer considering swimming to their mouthpiece in place, risks of an ascent line rather than drifting far from drowning are quite high, even if the the boat.