Abstract

Plasma concentrations of lidocaine were measured over a period of 3 hours following endotracheal intubation of patients with tubes which were lubricated with lidocaine 5% (Xylocaine^®) ointment (18 patients) or lidocaine 2% (Xylocaine^® HCI) Jelly (16 patients). The average amount of ointment or jelly used on the tubes was 1.25 g (0.49-2.45 g). Peak blood levels were obtained within 5 to 15 minutes after intubation. The mean peak level was about 0.5 μg/ml for the ointment and below the accurately measurable level for the jelly. The highest peak plasma concentration of 0.9 μg/ml was obtained with the ointment in one patient within the first 5 minutes after intubation. Following use of the jelly, at no time did plasma concentration exceed 0.2 mcg/ml. With both preparations the levels of lidocaine were far below those producing systemic effects.