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: l ( - 1 ) with lidocaine infusion ( 6 mg . kg ( - 1 ) . min ( - 1 ) ) , increasing significantly to 66 . 6 + / - 10 . 9 mg .
### Output Text:
l ( - 1 ) with <span class="chemical">lidocaine</span> infusion ( 6 mg . kg ( - 1 ) . min ( - 1 ) ) , increasing significantly to 66 . 6 + / - 10 . 9 mg . 