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 increase in dP / dtejc during infusion of dobutamine in this group was severely impaired as compared to the non - ischemic group .
### Output Text:
The increase in dP / dtejc during infusion of <span class="chemical">dobutamine</span> in this group was severely impaired as compared to the non - ischemic group . 