Normally there are 2 mechanisms that may protect a person in a low oxygen environment:
(1) dyspnea as the arterial blood develops oxygen desaturation
(2) hypercarbia/hypercapnea
Under certain circumstances both mechanisms may fail to alert the person to impending asphyxia.
Risk factors for death during nitrous oxide inhalation:
(1) breathing nitrous oxide at a high concentration, without oxygen (as from an industrial tank)
(2) intoxication with drugs or alcohol
(3) other disorders affecting the responsiveness of the respiratory center (COPD, etc)
(4) use when alone without companions
Scene investigation and toxicology may be necessary to distinguish between:
(1) accidental death
(2) suicide
(3) homicide
