Tissue distribution of lidocaine in critical care patients after intubation

We investigated tissue distribution of lidocaine in 33 patients after endotracheal intubation with Xylocaine jelly that contains 2% lidocaine hydrochloride. Blood levels of monoethylglycinexylidide (MEGX), an active metabolite of lidocaine, were also determined. Five patients (Group A) were alive on arrival and six patients (Group B) resumed heartbeats after cardiopulmonary resuscitation (CPR). The survival times for Groups A and B ranged from 3 to 72 h. The remaining 22 patients (Group C) did not survive cardiopulmonary arrest on arrival (CPAOA). Systemic distribution of lidocaine was measured in nine patients from Group C. The liver-to-kidney lidocaine ratios and cerebrum-to-cerebrospinal fluid lidocaine ratios were: Group A, 0.1-0.7 and 1.4-3.6, respectively; Group B, 0.2-0.8 and 1.2-2.3, respectively; Group C, 0.1-17 and 0.2-1.0, respectively. MEGX was detected in all blood samples from Group A and only two samples from Group B. No MEGX was detected in samples from Group C. Our results indicate that the absorption of tracheal lidocaine during natural circulation results in a cerebrum-to-cerebrospinal fluid lidocaine ratio of 1.2 or more, whereas absorption during artificial circulation by cardiac massage gives a ratio of 1.0 or less. The cerebrum-to-cerebrospinal fluid lidocaine ratio may be a more useful index to estimate circulatory dynamics of patients during CPR than the liver-to-kidney lidocaine ratio. MEGX was not a useful parameter for monitoring circulatory changes during cardiac massage.