Distribution of tetracaine and its metabolite in rabbits after high versus normal spinal anesthesia

Lidocaine intoxication: two fatal cases

We present two fatal cases, a 41-year-old male (case 1) and his 8-year-old daughter (case 2), resulting from acute lidocaine poisoning. Lidocaine was quantified by gas chromatography (GC) analysis using nitrogen-phosphorus detection. The lidocaine concentrations of cases 1 and 2 were: liver, 27.7 microg/g and 24.9 microg/g; spleen, 70.1 microg/g and 29.9 microg/g; and gastric contents, 23.6 microg/g and 42.8 microg/g, respectively.

A sudden death following tetracaine-induced spinal anesthesia

A 56-year-old Japanese woman died after being given 10 mg of tetracaine to induce spinal anesthesia in preparation for orthopedic surgery. Autopsy findings and microscopic analysis revealed no external injuries or disease, and further toxicological examinations were carried out to determine the cause of death. For this we used gas chromatography-mass spectrometry. Tetracaine was not detected in most tissue samples, but the metabolite, p-butylaminobenzoic acid, was clearly detected in all samples. The concentration of the metabolite in the brain stem (234.7 ng/g) was higher than in the cerebrum (30.5 ng/g), cerebellum (36.7 ng/g), whole blood of the left heart (164.8 ng/ml) and whole blood of the left femoral vein (84.0 ng/ml). These distribution patterns were exactly same as rabbits sacrificed by high spinal anesthesia. Our findings suggest that tetracaine spread to the high regions of cerebrospinal nerves and acted directly on the central nervous system. Therefore, the cause of her death was high spinal anesthesia induced by tetracaine. This is apparently the first toxicologically proven case in which spinal anesthesia affected high brain centers.