Aminophylline treatment for asthma (in the emergency sense, restricted to IV administration) is something purely for the A&E because of the risk of cardiac arrythmias, or at least that is the thinking over here. Generally we can keep people alive using Salbutamol nebulisers and if serious enough, with a shot of epinephrine. Anyone that is having a serious asthma attack needs to be in hospital rather than sitting in an ambulance while you try to start an IV line and mix up the drug. One of the bonuses of working in London is that we are normally very close to a hospital. (5 minutes by blue-light).