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: CONCLUSION : In summary , our results indicate that airway management using FRLMA during controlled hypotension anesthesia provided better surgical conditions in terms of quality of operative field and blood loss and allowed for convenient induced hypotension with low doses of remifentanil during TIVA in patients undergoing FESS .
### Output Text:
CONCLUSION : In summary , our results indicate that airway management using FRLMA during controlled hypotension anesthesia provided better surgical conditions in terms of quality of operative field and blood loss and allowed for convenient induced hypotension with low doses of <span class="chemical">remifentanil</span> during TIVA in patients undergoing FESS . 