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: RESULTS : NaHCO3 briefly ( 5 min ) reversed hypotension and QRS prolongation .
### Output Text:
RESULTS : <span class="chemical">NaHCO3</span> briefly ( 5 min ) reversed hypotension and QRS prolongation . 