Obstructive sleep apnea on C-PAP, 12 mm HG.
 The patient has episodes of apnea while sleeping. 
(ROOT (NP (NP (JJ Obstructive) (NN sleep) (NN apnea)) (PP (IN on) (NP (NN C-PAP))) (, ,) (NP (CD 12) (NN mm) (NNP HG)) (. .)))
(ROOT (S (NP (DT The) (NN patient)) (VP (VBZ has) (NP (NP (NNS episodes)) (PP (IN of) (NP (NN apnea)))) (SBAR (IN while) (NP (VBG sleeping)))) (. .)))
( ( ( ( ( Obstructive ( sleep apnea ) ) ( on C-PAP ) ) , ) ( 12 ( mm HG ) ) ) . )
( ( The patient ) ( ( ( has ( episodes ( of apnea ) ) ) ( while sleeping ) ) . ) )