In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: METHODS : Sixty normotensive American Society of Anesthesiologists I - II adult patients undergoing FESS under controlled hypotension anesthesia caused by propofol - remifentanil - TIVA were randomly assigned into two groups : group I , FRLMA ; group II , ETT .
### Output Text:
METHODS : Sixty normotensive American Society of Anesthesiologists I - II adult patients undergoing FESS under controlled hypotension anesthesia caused by <span class="chemical">propofol</span> - <span class="chemical">remifentanil</span> - TIVA were randomly assigned into two groups : group I , FRLMA ; group II , ETT . 