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: After one week of therapy , he was transferred to the intensive care unit with cardiopulmonary compromise related to superior vena cava ( SVC ) syndrome .
### Output Text:
After one week of therapy , he was transferred to the intensive care unit with cardiopulmonary compromise related to superior vena cava ( SVC ) syndrome . 