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: While use of high dose dexmedetomidine is associated with decreases in heart rate and blood pressure outside the established ' awake ' norms , this deviation is generally within 20 % of norms , and is not associated with adverse sequelae .
### Output Text:
While use of high dose <span class="chemical">dexmedetomidine</span> is associated with decreases in heart rate and blood pressure outside the established ' awake ' norms , this deviation is generally within 20 % of norms , and is not associated with adverse sequelae . 