Patient was sent back to the Emergency Department today because of difficulty breathing.
 The patient has a COPD exacerbation. 
(ROOT (S (NP (NN Patient)) (VP (VBD was) (VP (VBN sent) (ADVP (RB back) (PP (TO to) (NP (DT the) (NNP Emergency) (NNP Department)))) (NP (NN today)) (PP (IN because) (IN of) (NP (NN difficulty) (NN breathing))))) (. .)))
(ROOT (S (NP (DT The) (NN patient)) (VP (VBZ has) (NP (DT a) (NNP COPD) (NN exacerbation))) (. .)))
( Patient ( ( was ( ( ( sent ( back ( to ( the ( Emergency Department ) ) ) ) ) today ) ( because ( of ( difficulty breathing ) ) ) ) ) . ) )
( ( The patient ) ( ( has ( a ( COPD exacerbation ) ) ) . ) )