▁hour ▁or ▁so ▁of ▁slow ▁decom pression . ▁ ▁The ▁Norwegian ▁s atur ation ▁decom pression ▁tables ▁are ▁similar , ▁but ▁specifically ▁do ▁not ▁allow ▁decom pression ▁to ▁start ▁with ▁an ▁up ward ▁exc urs ion . ▁Part ial ▁pressure ▁of ▁o xygen ▁is ▁maintained ▁between ▁ 0 . 4 ▁and ▁ 0 . 5 ▁bar , ▁and ▁a ▁rest ▁stop ▁of ▁ 6 ▁hours ▁is ▁specified ▁each ▁night ▁starting ▁at ▁mid night . ▁ ▁Th era pe ut ic ▁decom pression ▁▁ ▁Th era pe ut ic ▁decom pression ▁is ▁a ▁procedure ▁for ▁tre ating ▁decom pression ▁sick ness ▁by ▁recom press ing ▁the ▁diver , ▁thus ▁reducing ▁b ubble ▁size , ▁and ▁allowing ▁the ▁gas ▁b ub bles ▁to ▁re - d iss ol ve , ▁then ▁decom press ing ▁slowly ▁enough ▁to ▁avoid ▁further ▁formation ▁or ▁growth ▁of ▁b ub bles , ▁or ▁elimin ating ▁the ▁in ert ▁g ases ▁by ▁breath ing ▁o xygen ▁under ▁pressure . ▁ ▁Th era pe ut ic ▁decom pression ▁on ▁air ▁ ▁Re com pression ▁on ▁atmos pher ic ▁air ▁was ▁shown ▁to ▁be ▁an ▁effective ▁treatment ▁for ▁minor ▁D CS ▁sympt oms ▁by ▁Ke ays ▁in ▁ 1 9 0 9 . ▁ ▁Histor ically , ▁th era pe ut ic ▁decom pression ▁was ▁done ▁by ▁recom press ing ▁the ▁diver ▁to ▁the ▁depth ▁of ▁relief ▁of ▁pain , ▁or ▁a ▁bit ▁deeper , ▁maintain ing ▁that ▁pressure ▁for ▁a ▁while , ▁so ▁that ▁b ub bles ▁could ▁be ▁re - d