Acute poisoning death resulting from a veterinary employee's isoflurane abuse

Isoflurane is a volatile inhalation anesthetic used primarily in veterinary medicine and, recently, infrequently in human medical applications. However, it is sometimes abused for recreational or suicidal purposes by medical and research personnel. We present a forensic autopsy case of a man in his 40 s who was employed at a veterinary hospital and was suspected to have died from isoflurane poisoning. Autopsy findings showed no injuries or lesions, and the pathological findings of most organs suggested acute death. Routine gas chromatography-mass spectrometry analysis for blood alcohol showed no ethanol, but showed a peak that was identified as isoflurane. Quantitative analysis of isoflurane in blood and tissues was performed by gas chromatography-mass spectrometry. The isoflurane concentrations in the left and right heart blood and femoral blood were 49.8, 54.6, and 44.7 µg/mL, respectively. These concentrations were similar to those recorded in previous fatal isoflurane poisoning cases, and we concluded that the decedent had inhaled a high concentration of isoflurane using a plastic bag and died owing to acute toxicity resulting in respiratory failure. Tissue distribution patterns aligned with the lipophilic nature of isoflurane: adipose tissue had the highest isoflurane concentration (779.8 µg/mL), and the concentrations were higher in liver (194.2 µg/mL) and brain (149.0 µg/mL) tissues than in others. This case highlights a grave concern regarding the management of drugs that may be abused in veterinary clinics in Japan. Stricter controls and pharmacist involvement in veterinary medication management are needed to prevent the abuse of these drugs.