Looking at it strictly as an EMT-B according to the registry anything over 90 is technically high enough. Now I'll be the first to admit that much of the information in this thread was miles over my head as we haven't hit on cardiology yet but from what I've understood it sounds like it's not the actual end number of the BP that's truely important it's how far it dropped. Say you had a patient go from 180 systolic to 110 systolic vs a patient at 90 systolic dropped to 75 systolic I think the first one is what we're worrying about. That second patient under our protocols wouldn't qualify for a second dose where the first patient technically would but I think I'd make use of the peddle on the right and let the doc give that second dose to either one.
Don't get hung up on BP. The most important things to realise are these.
What is GTN and how does it work? How does GTN fit into the scheme of things for the cardiac pt? Where does GTN fit into your protocol for the management of cardiac chest pain/ACS?
Learn the drug sheet and follow the guidelines on its use. Realise it is a powerful, potentially dangerous drug but is versatile and effective as well.
Also realise that
ALL drugs have effects (benefits or uses as a tool to achieve a specific goal) and side effects (concurrent undesireable or counter-productive effects). And on occasion we may exploit either of these things to achieve a goal.
But remember that these chemicals are tools we use, are usually very specific and have limited uses. They are also tested, checked for safety using many medical studies, and distributed for use to various health professsionals (including us) to be used after careful consideration of their benefits to the most number of people the maximum amount of times possible.
But they are neither foolproof nor 100% reliable because everybody is different. No two people have identical medical problems.
So when you pull out your nitro spray or tablet remember that it is a dumb chemical and once it's in, it's in. There is no Naloxone for GTN.
So gather information - as much as you can given the circumstances - use your 12lead, check contraindications AND precautions. Know the onset times and duration of effect. And above all talk to the patient - they know their own condition better than anyone.
If you do all these things but still have doubts or uncertainties you still have several options. Give less than the prescribed dose. Give none and look for alternatives - if its pain and GTN is a worry and you can give Morph then think about it. Check your partner, check your medical controller. If in doubt -transport is still treatment. Give the O2, give the aspirin, rest the patient.
If they are sick call for backup.
Nobody expects you to be a cardiologist but you must still act prudently and with judgement and common sense.
If you are giving an 80yo woman with a Hx of IHD AMI/angina, hypertension etc and she has cardiac pain with a BP of 105sys and a HR of 120/min, (marginal perfusion numbers), a drug that works by dropping preload and after load - blood pressure going in and going out, what do you think will happen and what must you do?
Work the problem - respect the patient.
It all about the margin for error that you have before you. Thats right - its a numbers game. Always stack the odds in favour of the patient.
MM