tourniquet   (tight   enough   to   impede   the   venous return  of  blood  to  the  trunk,  yet  loose  enough  to allow  arterial  supply  to  the  extremity)  will  further delay   systematic   absorption   of   the   poison.   Place a  tourniquet  between  the  bite  and  the  heart,  about 2   inches   above   the   bite.   A   tourniquet   should only   be   used   if   competent   medical   help   is reasonably   expected   to   take   over   management   of a   snakebite   victim. 2.   Clean   a   knife   or   razor   blade   and   the   fang marks   by   daubing   with   antiseptic,   if   available. 3.   Make   a   small   cut   over   each   fang   mark (deep   enough,   one-fourth   of   an   inch   or   more,   to penetrate   the   skin).   Orient   each   cut   parallel   to   vital structures   (generally   parallel   to   the   long   axis   of the   limb). 4.   Apply   suction.   Suction   can   best   be   applied by   mouth,   but   not   if   there   are   open   oral   lesions present.   In   this   case,   some   other   means   of applying   suction   must   be   found.   After   30   minutes, suction   is   of   little   benefit. CARE   OF   WOUNDS.—   Open  wounds  are  a serious   hazard   in   a   survival   situation,   not   only because   of   the   tissue   damage   and   blood   loss,   but also   because   of   the   increased   possibility   of infection.   Little   can   be   done   to   prevent   wound contamination   at   the   time   of   the   injury.   Proper wound   care   can   minimize   further   contamination and   promote   healing   and   preservation   of   function in   the   injured   part. .   Clothing   should   be   cut   or   torn   away   from a   wound;   drawing   clothes   over   the   wound   may introduce   bacteria   into   the   wound. l   Whenever   possible,   avoid   touching   the wound   with   fingers   or   any   unsterile   object.   All water   and   instruments   used   in   wound   care   should be   sterilized   by   boiling.   Washing   your   hands before   you   treat   any   wound   is   very   important   in keeping   down   infection. .   Clean   all   wounds   as   soon   after   occurrence as   possible.   Only   antiseptics   especially   designed to  use  in  open  wounds  should  be  used  directly  in the   wound. NOTE:   Common   antiseptics   such   as   Mer- thiolate,   iodine,   and   Mercurochrome   should   never be   applied   directly   to   a   wound.   These   solutions destroy   only   part   of   the   bacteria   and   actually damage   the   exposed   tissues. .   When   cleansing   solutions   for   wounds   are not   available,   a   suitable   substitute   may   be   a poultice   made   of   fern   root.   To   prepare   a   poultice, you   boil   finely   chopped   roots   in   water   until syrupy.   Allow   the   poultice   to   cool   and   apply directly   to   the   wound. .   The   “open   treatment”   method   is   the   safest way   to   manage   wounds   in   a   survival   situation.   No attempt   should   be   made   to   close   a   wound   by stitching.   The   wound   should   be   left   open   to permit   drainage   of   pus   from   infection.   As   long as   a   wound   can   drain,   it   generally   will   not   become life   threatening.   If   a   wound   is   gaping,   the   edges can   be   brought   together   with   adhesive   tape   cut in   the   form   of   a   butterfly   or   dumbbell.   When   a butterfly   bandage   is   applied   properly,   only   a   small portion   of   the   adhesive   is   in   contact   with   the wound;   but   a   large   surface   of   the   tape   is   in contact   with   the   skin   on   either   side   of   the   wound, providing   traction   that   pulls   the   edges   of   the wound   together.   The   narrow   center   permits   some free   drainage   from   the   wound,   and   the   strips   can be  removed  easily  if  the  wound  has  to  be  opened should   infection   develop. Exposure In   certain   climates,   you   will   be   exposed   to excessive   heat   or   cold   and   must   safeguard   yourself from   its   effects.   Proper   procedure   is   the   key   to prevention   of   all   cases   of   heat   or   cold   exposure. HEAT.— Increased sweating requires more fluid   intake.   The   duration   of   physical   activity should   be   less   during   the   first   days   of   heat exposure   and   increased   gradually   as   you   become acclimatized.   Alternate   work   and   rest   periods should   be   established.   Avoid   working   in   direct   sun or   on   extremely   hot   days.   Wear   lighter   clothing in   hot   environments. C O L D . —   The   most   important   aspect   of prevention   of   cold-related   injury   is   awareness   of existing   weather   conditions   and   the   likelihood   of weather   change.   Adequate   clothing   to   protect   as much   exposed   skin   as   possible   must   be   worn.   Rain gear   should   be   donned   before   you   become   wet; wool   clothes   and   wind-protective   garments   should be   donned   before   you   start   to   shiver.   Improvised clothing   may   be   made   from   parachute   material. Obtain   shelter   that   provides   protection   from   the wind,   precipitation,   and   surface   water   as   well as   insulation   from   ground,   snow,   or   ice.   Impro- vised   shelters,   described   in   Survival   Training 5-41