Yes. I was an ambulance paramedic for many many years (certification is expired now - "I'm too old for that s*%^"). Training officer. I certainly wouldn't ignore "unofficial" medical information found on a patient (I wouldn't go hunting for it either though, I'd just do a quick check of the typical medic alert tag locations). Back in the day, if I ran into an unconscious patient in V-Fib, and after shocking found a medic alert tag mentioning a severe allergy to Lidocaine, I most certainly would radio the ER physician and discuss using Bretylium instead. Failing successful contact, I would have made the choice on my own for Bretylium over Lidocaine, even though Lidocaine is usually first line per protocol. However, as I said, nobody would do something so stupid as starting a blood transfusion based solely on info on a medic alert tag, not that blood transfusions are done in the back of an ambulance in the first place. If you find a Paramedic/ER nurse who would disagree with the above, they're not very good and I certainly wouldn't want them treating me. (Note: Above I was talking about treatment protocols that were the norm back when I was a Paramedic, protocols may have changed since then, but I wouldn't know that now, as I've been away from it since the mid-90's.)