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: We describe a case of transient neurological deficit that occurred after unilateral spinal anaesthesia with 8 mg of 1 % hyperbaric bupivacaine slowly injected through a 25 - gauge pencil - point spinal needle .
### Output Text:
We describe a case of transient neurological deficit that occurred after unilateral spinal anaesthesia with 8 mg of 1 % hyperbaric <span class="chemical">bupivacaine</span> slowly injected through a 25 - gauge pencil - point spinal needle . 