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: Sedation has been commonly used in the neonate to decrease the stress and pain from the noxious stimuli and invasive procedures in the neonatal intensive care unit , as well as to facilitate synchrony between ventilator and spontaneous breaths .
### Output Text:
Sedation has been commonly used in the neonate to decrease the stress and pain from the noxious stimuli and invasive procedures in the neonatal intensive care unit , as well as to facilitate synchrony between ventilator and spontaneous breaths . 