Determining the state of the deceased during cardiopulmonary resuscitation from tissue distribution patterns of intubation-related lidocaine

The objective of this study was to determine whether the concentrations of lidocaine, used for endotracheal intubation, in body fluids and tissues reflect the state of the circulation of the deceased during cardiopulmonary resuscitation. The tissue distribution of lidocaine was investigated in seven individuals (Cases 1-7) who underwent medical treatment with endotracheal intubation using Xylocaine jelly (a 2% lidocaine hydrochloride preparation), before being pronounced dead. Six patients (Cases 1-6) had cardiopulmonary arrest on arrival at hospital. In Cases 1-4, there was no restoration of heartbeat during cardiopulmonary resuscitation. However, systemic distribution of intubation-related lidocaine was observed and the kidney-to-liver ratios of lidocaine were less than 1. In Cases 5 and 6, the heartbeat resumed temporarily with cardiac massage, and a kidney-to-liver lidocaine ratio greater than 1 was observed. In Case 7, where the patient was comatose upon admission to hospital, the kidney-to-liver ratio of lidocaine was also greater than 1. These phenomena were substantiated in animal experiments. Our results indicate that the absorption of tracheal lidocaine during the artificial circulation resulting from cardiopulmonary resuscitation results in a kidney to liver ratio of less than 1, whereas absorption during natural circulation gives a ratio greater than 1. The kidney-to-liver ratio of intubation-related lidocaine may give useful information on the state of a patient during cardiopulmonary resuscitation.