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: Although dexmedetomidine sedation was associated with a 16 % incidence of bradycardia , all concomitant mean arterial blood pressures were within 20 % of age - adjusted normal range and oxygen saturations were 95 % or higher .
### Output Text:
Although <span class="chemical">dexmedetomidine</span> sedation was associated with a 16 % incidence of bradycardia , all concomitant mean arterial blood pressures were within 20 % of age - adjusted normal range and <span class="chemical">oxygen</span> saturations were 95 % or higher . 