As an intravenous heroin user, I regularly inject into my veins and the pain, while not non-existent, is pretty minimal, unless I cannot access the vein due to thrombosis/collapse. This has always worried me, since it can take me half an hour to place a shot, and in hospital I have had multiple nurses and doctors try to insert a cannula over similar lengths of time. In a life threatening situation I have often wondered what would happen when the EMT could not get access. The existence of IO needles is interesting, therefore, since on IVDA patients they will still work - I just wonder how common a piece of kit they are in UK ambulances and A&E departments?