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: METHODS AND RESULTS : In 20 patients ( 14 men and 6 women aged 39 to 72 years ) referred for cardiac catheterization for the evaluation of chest pain , we measured heart rate , systemic arterial pressure , LV pressure and its first derivative ( dP / dt ) , and LV volumes and ejection fraction before and during the final 2 to 3 minutes of a 15 - minute intracoronary infusion of saline ( n = 10 , control subjects ) or cocaine hydrochloride 1 mg / min ( n = 10 ) .
### Output Text:
METHODS AND RESULTS : In 20 patients ( 14 men and 6 women aged 39 to 72 years ) referred for cardiac catheterization for the evaluation of chest pain , we measured heart rate , systemic arterial pressure , LV pressure and its first derivative ( dP / dt ) , and LV volumes and ejection fraction before and during the final 2 to 3 minutes of a 15 - minute intracoronary infusion of saline ( n = 10 , control subjects ) or <span class="chemical">cocaine hydrochloride</span> 1 mg / min ( n = 10 ) . 