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: The patient continued to remain hypotensive with complete heart block , even with multiple uses of intravenous atropine as well as high doses of pressor agents such as dopamine and dobutamine .
### Output Text:
The patient continued to remain hypotensive with complete heart block , even with multiple uses of intravenous <span class="chemical">atropine</span> as well as high doses of pressor agents such as <span class="chemical">dopamine</span> and <span class="chemical">dobutamine</span> . 