The clarification of the vital states of patients during cardiopulmonary resuscitation before being pronounced dead may help considerably in differentiating injuries caused by cardiopulmonary resuscitation from antemortem traumas. In the current study, the concentrations of lidocaine and MEGX in blood, pericardial fluid, bile, and/or urine were measured for 16 patients who had received endotracheal intubation using XylocaineTM jelly, a 2-percent w/v lidocaine hydrochloride preparation. Lidocaine was detected in all of the 16 cases. Of six patients who had survived 3 hours to 10 days following endotracheal intubation, four were MEGX-positive and two were negative. No MEGX was detected in the other 10 patients whose hearts had not resumed beating despite attempts at cardiopulmonary resuscitation. MEGX can be an indicator of the vital state of a patient during cardiopulmonary resuscitation; it shows the antemortem use of lidocaine under normal hepatic conditions. 3 tables and 11 references