Differences in plasma lidocaine levels with endotracheal drug therapy secondary to total volume of diluent administered.

Abstract

Endotracheal drug therapy provides an effective alternative method for the administration of drugs in the numerous clinical settings in which intravenous access is difficult or impossible to obtain. However, the specific factors affecting endotracheal drug absorption and thus, the drug's plasma levels and effectiveness, has not yet been fully determined. Lidocaine alone or lidocaine mixed with normal saline was given endotracheally in four volumes (Volume I = undiluted with less than or equal to 5.5 cc total volume; Volume II = diluted to 6 cc total volume; Volume III = diluted to 12 cc total volume; Volume IV = diluted to 25 cc total volume) by the same technique of administration and in the same dosage of 4 mg/kg. Each dog served as its own control and received all four volumes of endotracheal lidocaine on different occasions. Plasma lidocaine levels at all four volumes and at all four time periods (5, 15, 30 and 60 min after giving endotracheal lidocaine) were obtained in each of the six dogs for a total of 96 plasma lidocaine levels measured in the study. Mean plasma lidocaine levels (micrograms/ml) at 5 min were: Volume I = 1.9, Volume II = 10.0, Volume III = 3.2 and Volume IV, = 4.3. These results were highly significant (P less than 0.001). The highest plasma lidocaine levels were obtained in the diluted volume, Volume II and the lowest plasma lidocaine levels in the undiluted volume, Volume I, with Volumes III and IV being intermediate.(ABSTRACT TRUNCATED AT 250 WORDS)