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: Four ( 10 . 8 % ) patients in the conventional group and 1 ( 2 . 7 % ) in the unilateral group , P = 0 . 17 required epinephrine infusion to treat hypotension .
### Output Text:
Four ( 10 . 8 % ) patients in the conventional group and 1 ( 2 . 7 % ) in the unilateral group , P = 0 . 17 required <span class="chemical">epinephrine</span> infusion to treat hypotension . 