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 average plasma lidocaine level 10 minutes after administration for patients without a myocardial infarction was significantly higher than that for patients with an acute infarction .
### Output Text:
The average plasma <span class="chemical">lidocaine</span> level 10 minutes after administration for patients without a myocardial infarction was significantly higher than that for patients with an acute infarction . 