On weaning to 6L NC, his O2 sat decreased to 81-82%
 Patient has poor O2 sats
(ROOT (FRAG (PP (IN On) (S (VP (VBG weaning) (PP (TO to) (NP (NN 6L) (NN NC)))))) (, ,) (PRP$ his) (NX (CD O2) (VP (VBD sat) (VP (VBN decreased) (PP (TO to) (NP (CD 81-82) (NN %))))))))
(ROOT (S (NP (NN Patient)) (VP (VBZ has) (NP (JJ poor) (CD O2) (NNS sats)))))
( ( On ( weaning ( to ( 6L NC ) ) ) ) ( , ( his ( O2 ( sat ( decreased ( to ( 81-82 % ) ) ) ) ) ) ) )
( Patient ( has ( poor ( O2 sats ) ) ) )