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MARCH 21, 2010 REVIEW BY PARAMEDIC DIVER AND WORLD RECORD HOLDER JOE TOBIN

DIVING INSTRUCTOR DAVID LAIRD (LEFT) AND AUTHOR PARAMEDIC JOE TOBIN (RIGHT) 

Those of us who freedive, have the opportunity to experience the underwater world in a very unique and challenging way.   Many freedivers would not want to experience the underwater world in any way other than freediving.   Sadly, our sport comes with a deadly risk that has claimed the lives of many including some of the most skilled and accomplished freedivers.  The deadly risk of our sport is known as shallow water blackout (SWB) and can strike any freediver no matter how cautious and conservative they may be about their personal diving practices.

SWB is the sudden loss of consciousness that occurs without warning at any phase of a breath hold dive but most often occurs just prior to reaching the surface after a dive.  There are few experienced freedivers who do not know of someone who has died from SWB. 

An unwitnessed SWB leads to near certain doom for any diver who experiences it.  An unconscious freediver, cannot swim to the surface for air or perform the snorkel clearing procedures that freedivers do after every dive as a matter of routine.  Even with the use of a vigilant buddy diver, too many uncontrollable variables can arise that can lead to an unconscious diver being overlooked or missed altogether after a blackout.    Strong ocean currents, poor visibility, depth that exceeds the capability of potential rescuers and other variables can effectively close the window of opportunity to locate, retrieve and begin resuscitation of the SWB victim. 

Let us begin by understanding the problem of SWB in more detail.  Once an SWB occurs in a freediver, a narrow window of opportunity exists to attempt to rescue the unconscious diver.  Time is of the essence!  The treatment of choice following retrieval of an SWB victim is to immediately open the airway and begin rescue breathing.  In the minutes following an SWB, critical time is often lost trying to locate the stricken diver.   

From the time the freediver becomes unconscious underwater, the drowning process begins.  At the point of unconsciousness, when the diver can no longer willfully hold his breath, involuntary breathing draws water into the mouth and onward toward the lungs.  In some cases, it is thought that a reflexive spasm of the larynx may temporarily block water from entering the lungs but there is strong debate as to the frequency of this occurrence or how long it lasts.  Studies have shown that 90% of drowning victims have aspirated some degree of water into the lungs.  Water entering the lungs causes damage to lung tissues and interferes with oxygen exchange.  Lack of oxygen to the other organs in the body including the brain is damaging and can become irreversible within 6 minutes if breathing is not restored.  Further, if rescue breathing is not started, the heart will eventually stop beating.    Though there have been some successful outcomes, the survival rate for drowning victims who require chest compressions is poor. 

Fortunately, survival statistics from drowning can be quite high if the victim is submerged less than 5 minutes and receives prompt basic life support including opening the airway and delivery of rescue breathing.   In cases where rescue efforts are delayed from 5 to 10 minutes, chances of survival plummet drastically.  Sadly, there have been too many instances of freedivers blacking out and remaining submerged beyond the prime window of opportunity for intervention.  

With over four decades of freediving experience, Dr. Terry Maas has studied the issue of SWB and recently developed the Freediver’s Recovery Vest.  This streamlined device is similar to an inflatable life vest.   It contains a sophisticated software system that is user programmable and can be set with time and depth limit parameters.  Once these self programmed parameters are exceeded, the vest’s innovative compressed air cylinder will self inflate the integral high volume air bladder and return the diver to the surface in a face up position.  The goal of the Freediver’s Recovery Vest is to save critical time lost after a blackout in trying to locate and retrieve the unconscious diver.  If an unconscious diver can be brought to the surface promptly after exceeding his self programmed time or depth profile, then rescue by his dive buddy can begin promptly and greatly enhance the chances of survival for the SWB victim. 

Due to Terry’s efforts along with the help from an incredibly diverse group of contributors to the concept, the Freedivers Recovery Vest has moved from concept to working model.  Due to the serious nature of the project, it was apparent from the beginning that the Freediver’s Recovery Vest must be constructed with the same dependability as a medical device or critical aircraft component.  This is why the vest has been designed with rugged materials and redundant systems where required to ensure flawless operation when activated. 

Recently I had the opportunity to participate in an evaluation of the vest under typical freediving conditions.  As a freediver and avid spearfisherman, I had an interest in seeing for myself if the vest would interfere in any way in my ability to dive as I normally do while hunting.   As others have reported, the vest fit comfortably and exceeded my expectations but I had more important objectives to pursue.   My second and most important objective was to evaluate how the vest would affect a simulated rescue of a freediver in need of rescue breathing.   

Using avid freediver David Laird as my test subject, I observed several scenarios where the Freediver’s Recovery Vest self inflated after David intentionally exceeded his self programmed depth and time limits.  In all cases, the vest inflated quickly and brought David to the surface where he remained floating in a face up position.  My next effort was to assess simulated rescue breathing.  In this trial, I was impressed at how much buoyancy the vest provided.   After removing David’s weight belt and mask as well as my own, I found that rescue breathing could be performed in the water very easily.   

 

One very important concept in rescue breathing is to maintain proper head tilt to ensure the tongue does not obstruct the airway in the unconscious victim.  This task is easy enough to perform on land but how about in the water?  I found that the inflated vest not only helped maintain proper head tilt but that I could also deliver simulated rescue breaths very easily on account of the buoyancy provided.   During the in-water rescue breathing drills, my test subject’s head was always well clear of the water surface which would be an important advantage when trying to provide rescue breathing in the water.

 

Another important discovery was that by reaching between my test subjects arm and chest then gripping the shoulder harness portion of the vest, I could easily swim towards safety while simultaneously delivering rescue breaths.   

It is clear to me that the Freediver’s Recovery Vest resolves several important problems surrounding SWB blackout in freedivers.  By returning the diver promptly to the surface and providing good buoyancy and positioning of the victim’s airway, a vigilant dive buddy can more quickly begin rescue breathing in the critical first minutes following an SWB.  I am convinced that combining use of the Freediver’s Recovery Vest along with continued safe freediving practices including using the buddy system and knowledge of basic rescue breathing techniques, lives will be saved. 

Joe Tobin is a licensed California Firefighter-Paramedic with three decades of emergency pre-hospital care experience.  Joe spent 15 years of his career working along the Central California Coast where he led the resuscitation of numerous drowning victims at the Advanced Cardiac Life Support level.  He is also an avid freediver and spearfisherman and holds state and world spearfishing records.  His underwater photographs and articles have appeared in numerous publications.