I WR ) ▁is ▁the ▁emer gency ▁treatment ▁of ▁decom pression ▁sick ness ▁( D CS ) ▁by ▁sending ▁the ▁diver ▁back ▁under water ▁to ▁allow ▁the ▁gas ▁b ub bles ▁in ▁the ▁t issues , ▁which ▁are ▁causing ▁the ▁sympt oms , ▁to ▁resolve . ▁It ▁is ▁a ▁ris ky ▁procedure ▁that ▁should ▁only ▁be ▁used ▁when ▁it ▁is ▁not ▁pract ic able ▁to ▁travel ▁to ▁the ▁nearest ▁recom pression ▁chamber ▁in ▁time ▁to ▁save ▁the ▁victim ' s ▁life . ▁ ▁The ▁procedure ▁is ▁high ▁risk ▁as ▁a ▁diver ▁suffering ▁from ▁D CS ▁may ▁become ▁par al ys ed , ▁un cons cious ▁or ▁stop ▁breath ing ▁whilst ▁under ▁water . ▁Any ▁one ▁of ▁these ▁events ▁may ▁result ▁in ▁the ▁diver ▁d row ning ▁or ▁further ▁injury ▁to ▁the ▁diver ▁during ▁a ▁subsequent ▁rescue ▁to ▁the ▁surface . ▁These ▁ris ks ▁can ▁be ▁mit ig ated ▁to ▁some ▁extent ▁by ▁using ▁a ▁hel met ▁or ▁full - face ▁mask ▁with ▁voice ▁communic ations ▁on ▁the ▁diver , ▁and ▁susp ending ▁the ▁diver ▁from ▁the ▁surface ▁so ▁that ▁depth ▁is ▁posit ively ▁controlled , ▁and ▁by ▁having ▁an ▁in - water ▁stand by ▁diver ▁attend ▁the ▁diver ▁under going ▁the ▁treatment ▁at ▁all ▁times . ▁ ▁The ▁principle ▁behind ▁in ▁water ▁recom pression ▁treatment ▁is ▁the ▁same ▁as ▁that ▁behind ▁the ▁treatment ▁of ▁D CS ▁in ▁a ▁recom pression ▁chamber ▁ ▁Although ▁in - water ▁recom pression ▁is ▁regarded ▁as ▁ris ky , ▁and ▁to ▁be ▁avoided , ▁there ▁is ▁increasing ▁evidence