1898
METHODS : A total of 128 patients undergoing general surgery were randomly allocated to receive normal saline ( control ) or remifentanil to a target Ce of 2 ng ml ( - 1 ) ( R2 ) , 4 ng ml ( - 1 ) ( R4 ) , or 6 ng ml ( - 1 ) ( R6 ) administered via TCI .
 Chemical: remifentanil
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: remifentanil