SWB Shallow Water Blackout By Michelle Brislen

What is SWB?  Loss of Consciousness while in water  Usually caused by hyperventilation while freediving or breath-holding  Often happens to freedivers, athletes, and good swimmers.  Can happen in the ocean, pools, lakes, rivers, etc.

“Hero Worship” Image from NY Times

Energy Processes Cellular Respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy SugarOxygen Carbon Dioxide Water

How does it happen?  Release of CO 2 (Carbon Dioxide) through hyperventilation or deep exhales  When under water O 2 (Oxygen) is used up and turned in to CO 2  CO 2 is lower than normal because of hyperventilation thus decrease urge to breathe  Stay down/under water longer and O 2 continues to be used and deprives brain  Blackout occurs

Normal Dive SWB Dive Diagrams from Wikipedia Problem

Diagram from Aquatics International Shallow Water Blackout

How to Prevent SWB  Do not hyperventilate  Do not have breath-hold competitions under water  Do not perform underwater laps  When you feel the urge to breathe, begin your ascent “Leave something in the tank!”  Dive with a Buddy!!!! Maintain watch for 30 seconds after surfacing  Be weighted correctly and willing to release your belt if you’ve pushed it too far.  Tell your friends! Adults too!

References  shallowwaterblackoutprevention.org  “Confessions of a Freediving Spearo” by Sheri Daye; Hawaii Skin Diver Magazine 2010  rAquaticsInternationalFebruary2005.PDF  terDeathTheCombatEdge2003.pdf 