Two cases of suicide by asphyxiation due to helium and argon.

Numerous death cases due to suffocation in a toxic or oxygen deficient gas atmosphere have been described in the literature, but unfortunately especially cases involving inert gases like helium are often presented without detailed toxicological findings. Observations on two suicides are reported, one by helium and the other by argon inhalation. During autopsies gas samples from the lungs were collected directly into headspace vials by a procedure ensuring minimal loss and dilution. Qualitative gas analyses were performed using headspace gas chromatography-mass spectrometry (HS-GC/MS). For carrier gas the commonly used helium was replaced by hydrogen. Qualitative positive results were obtained in the argon case, but the case involving helium revealed negative findings. The use of HS-GC/MS enables in principle to detect inert gases like argon or helium. However, a number of factors may later influence the results as, e.g. a longer period of time between death and sampling or pre-analytical artefacts during sampling of such highly volatile substances. In absence of analytical data supporting helium exposure, the causes of death in the actual cases were found to be asphyxia and in both cases the manner was suicide.