ALSAFE Message 30/98 Shallow Water Blackout

RTTUZYUW RUCOPAW2927 2722146-UUUU--RHMCSUU. ZNR UUUUU R 292146Z SEP 98 FM COMNAVSAFECEN NORFOLK VA//00// TO ALSAFE BT UNCLAS //NO5100// ALSAFE 30/98 MSGID/GENADMIN/COMNAVSAFECEN/40-114/JUL// SUBJ/HAZARD ALERT (SHALLOW WATER BLACKOUT)// REF/A/GENADMIN/COMNAVSAFECEN/311300ZMAY96// REF/B/GENADMIN/COMNAVSAFECEN/132040ZMAY97// AMPN/REFS A AND B OUTLINED RISKS OF SHALLOW WATER BLACKOUT//

RMKS/ 1. RECENTLY A CHIEF PETTY OFFICER DROWNED AT A TRAINING ACTIVITY. HE WAS A SKILLED SWIMMER WHO DIED WHILE ALONE IN A POOL. INVESTIGATORS HAVE LEARNED THAT THE VICTIM WAS KNOWN TO PRACTICE BREATH-HOLDING TO EXTEND THE AMOUNT OF TIME HE COULD STAY SUBMERGED. WITH NO VISIBLE TRAUMA TO HIS BODY AND NO HISTORY OF HEART PROBLEMS, IT'S PROBABLE HE WAS TRYING TO SEE HOW LONG HE COULD HOLD HIS BREATH. TRAGICALLY, THERE WAS NO ONE AT THE POOL TO ASSIST HIM WHEN HE EXPERIENCED DIFFICULTY.

2. ONLY AEROBIC ACTIVITY SAFELY INCREASES ENDURANCE. HYPERVENTILATION COUPLED WITH UNDERWATER BREATH HOLDING IS AN EXTREMELY DANGEROUS PRACTICE. CARBON DIOXIDE (CO2) IS THE BRAIN'S STIMULUS FOR BREATHING. AS ITS PARTIAL PRESSURE IN THE BLOOD INCREASES, THE BRAIN SENSES THE BUILDUP AND AUTOMATICALLY CAUSES US TO TAKE A BREATH. HYPERVENTILATION INTERRUPTS THIS PROCESS BY RAPIDLY EXPELLING CO2 AND REDUCING THE URGE TO BREATHE. BREATH- HOLDING CAN CAUSE THE LEVEL OF OXYGEN IN THE BLOOD TO FALL DANGEROUSLY LOW BEFORE THE LEVEL OF CO2 RISES ENOUGH TO STIMULATE BREATHING. EXERCISE INCREASES THE DANGER BY DEPLETING OXYGEN LEVELS FASTER THAN NORMAL. LOW LEVELS OF OXYGEN CAN CAUSE SUDDEN LOSS OF CONSCIOUSNESS AND DEATH FROM DROWNING. ONE STUDY OF SURVIVORS OF NEAR-DROWNINGS REVEALED NEARLY ALL OF THEM HAD HYPERVENTILATED PRIOR TO SWIMMING AND HAD NO WARNING OF THEIR SUBSEQUENT UNCONSCIOUSNESS. THEY SURVIVED BECAUSE OTHERS OBSERVED THEIR PLIGHT AND SUCCESSFULLY RESUSCITATED THEM. HYPERVENTILATION IS SO DANGEROUS THAT THE U.S. NAVY DIVING MANUAL PROHIBITS IT AND PROFESSIONAL AQUATICS ORGANIZATIONS CAUTION AGAINST IT. REFERENCES (A) AND (B) HIGHLIGHTED THE DANGERS OF THIS PRACTICE.

3. THIS LATEST MISHAP ADDS ANOTHER PROBABLE TO THE GROWING NUMBER OF SAILORS AND MARINES WHO HAVE DIED FROM SHALLOW WATER BLACKOUT. LOSSES WILL CONTINUE IF WE DO NOT INCREASE AWARENESS OF THE DEADLY RISK IMPOSED BY HYPERVENTILATION AND BREATH HOLDING.

4. COMMANDERS, ENSURE PERSONNEL ARE THOROUGHLY BRIEFED ON A RECURRING SCHEDULE ABOUT THE DANGERS OF THIS PRACTICE. THE RISKS ARE THE SAME FOR COMBAT SWIMMERS AND RECREATIONAL SWIMMERS. PEOPLE MOST IN DANGER ARE THOSE PREPARING THEMSELVES FOR ADVANCED DIVER OR SWIMMER TRAINING SUCH AS BASIC UNDERWATER DEMOLITION SWIMMER OR RECONNAISSANCE TEAM MEMBER. TRAINEES REQUIRED TO PARTICIPATE IN BREATH HOLDING EXERCISES MUST BE CLOSELY SUPERVISED AND REMAIN IN DIRECT LINE OF SIGHT WITH AN OBSERVER. HYPERVENTILATION SHALL NOT BE PRACTICED. AQUATICS MANAGERS, POST YOUR FACILITIES TO PROHIBIT SWIMMERS FROM ENGAGING IN THIS ACTIVITY AND BRIEF YOUR LIFEGUARDS TO STOP ANYONE FROM DOING THIS WHO IS NOT IN A SUPERVISED TRAINING CLASS. SWIMMERS, DON'T HYPERVENTILATE OR PRACTICE BREATH-HOLDING. DON'T BE THE NEXT VICTIM OF SHALLOW WATER BLACKOUT. //

BT #2927 NNNN

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