"In the present analysis we found that overdose events were not uncommon at the Vancouver safer injection facility. During an 18-month period, 285 individuals accounted for 336 overdose events, yielding an overdose rate of 1.33 (95% CI: 0.0–3.6) overdoses per 1000 injections. Heroin was involved in approximately 70% of all overdoses, and opiates considered together were involved in 88%of overdoses. It is notable, however, that approximately one-third of overdoses involved stimulants. The most common indicators of overdose were depressed respiration, limp body, face turning blue, and a failure to respond to pain stimulus. The majority of overdoses were successfully managed in the SIF, with the most common overdose interventions undertaken by SIF staff involving the administration of oxygen, a call for ambulance support, and the administration of naloxone hydrochloride via injection. Among a randomly selected sample of SIF users, factors associated with time to overdose at the SIF included fewer years injecting, daily heroin use, and having a history of overdose. None of the overdose events occurring at the SIF resulted in a fatality."

Source

Thomas Kerr, Mark W. Tyndall, Calvin Lai, Julio S.G. Montaner, Evan Wood, "Drug-related overdoses within a medically supervised safer injection facility," International Journal of Drug Policy 17 (2006) p. 440.