4396
In this study , the general clinical criteria for inhalation injury - - presence of facial or oropharyngeal burns , carboxyhemoglobin levels , carbonaceous sputum , or closed space injury - - did not differentiate patients with airway injury only from those with parenchymal injury .
 carboxyhemoglobin
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 carboxyhemoglobin