IL18 and ventilator-associated pneumonia: Several biomarkers have been studied to predict the severity and prognosis of VAP, such as interleukin-18 (IL-18) and soluble triggering receptor expressed on myeloid cells 1 (sTREM-1),[9,10] histidine-rich glycoprotein,[11] pentraxin 3,[12] procalcitonin,[13,14] breath octane, acetaldehyde,[15] and C-reactive protein.[16] Procalcitonin, C-reactive protein, sTREM-1, and HRC have proven to be predictors of VAP; however, most are markers of inflammation, making them nonspecific.[9–11,13,14,16]