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.