2927
During the infusion of aminophylline , the ventricular fibrillation threshold was reduced by 30 to 40 percent of the control when pH and partial pressures of oxygen ( PO2 ) and carbon dioxide ( CO2 ) were kept within normal limits .
 aminophylline, ventricular fibrillation, oxygen, PO2, carbon dioxide, CO2
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 aminophylline, ventricular fibrillation, oxygen, PO2, carbon dioxide, CO2