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: Peak CE levels were associated with a 45 % ( SD + / - 22 % , 95 % CI = 22 % to 69 % ) decrease in cardiac output ( p < 0 . 05 ) , a 56 % ( SD + / - 23 % , 95 % CI = 32 % to 80 % ) decrease in dP / dt ( max ) ( p < . 006 ) , and a 23 % ( SD + / - 15 % , 95 % CI = 7 % to 49 % ) decrease in SVO ( 2 ) ( p < 0 . 025 ) .
### Output Text:
Peak <span class="chemical">CE</span> levels were associated with a 45 % ( SD + / - 22 % , 95 % CI = 22 % to 69 % ) decrease in cardiac output ( p < 0 . 05 ) , a 56 % ( SD + / - 23 % , 95 % CI = 32 % to 80 % ) decrease in dP / dt ( max ) ( p < . 006 ) , and a 23 % ( SD + / - 15 % , 95 % CI = 7 % to 49 % ) decrease in SVO ( 2 ) ( p < 0 . 025 ) . 