669
Operations lasting up to 2h could be performed in the absence of sophisticated equipment such as pulse oximeters or ventilators in patients on spontaneous ventilation breathing air / oxygen only .
 Chemical: oxygen
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: oxygen