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: All patients developed cardiocirculatory arrest associated with extreme hypotension and dysrhythmias within the first 48 hours of their admission to the pediatric intensive care unit ( PICU ) .
### Output Text:
All patients developed cardiocirculatory arrest associated with extreme hypotension and dysrhythmias within the first 48 hours of their admission to the pediatric intensive care unit ( PICU ) . 