In the Emergency Department, the patient was started on Nipride initially and then was switched to nitroglycerin.
 The patient was given a nitrate 
(ROOT (S (PP (IN In) (NP (DT the) (NNP Emergency) (NNP Department))) (, ,) (NP (DT the) (NN patient)) (VP (VP (VBD was) (VP (VBN started) (PP (IN on) (NP (NNP Nipride))) (ADVP (RB initially)))) (CC and) (S (ADVP (RB then)) (VP (VBD was) (VP (VBN switched) (PP (TO to) (NP (NN nitroglycerin))))))) (. .)))
(ROOT (S (NP (DT The) (NN patient)) (VP (VBD was) (VP (VBN given) (NP (DT a) (JJ nitrate))))))
( ( In ( the ( Emergency Department ) ) ) ( , ( ( the patient ) ( ( ( ( was ( ( started ( on Nipride ) ) initially ) ) and ) ( then ( was ( switched ( to nitroglycerin ) ) ) ) ) . ) ) ) )
( ( The patient ) ( was ( given ( a nitrate ) ) ) )