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: Since the cranial condition precluded use of more usual methods , lidocaine was given intra - arterially , with careful cardiovascular monitoring , to counteract the vasospasm .
### Output Text:
Since the cranial condition precluded use of more usual methods , <span class="chemical">lidocaine</span> was given intra - arterially , with careful cardiovascular monitoring , to counteract the vasospasm . 