First of all - relax a bit!
Terrified is not the best start of anything.
I think it is important to be deliberate.
(When in trouble, when in doubt - run in circles, scream and shout! -- KIDDING!!)
Really, just relax. Take a deep breath.
And NOW what can you do that is gonna help?
First, there is only 1 drug that I am aware of that is given in the ED that must be delivered undiluted and with meaning! That is ADENOSINE. No debate there.
Everything else you get a little time.
My rules:
I dilute most EVERYTHING. And I mean EVERYTHING whenever possible. (except Adenosine) (I will also exclude premixed syringe medications, paralytics, other RSI drugs)
Check your policies for any SPECIFICS - but, most issues of administration are left to accepted safe practice.
For a system. Start with this -
Most all hospitals have a drug formulary. These are the medications that are approved for use at your facility. Even more specific than this - most ED's that I have worked in have a (with rare exception) certain "set" of drugs that they use. Some are standing orders and others are specific to certain doc's.
Make yourself a "cheat sheet" if it helps you - but, never get too comfortable with it/dependent on it - always remember the 5 rights and remember you are a registered, professional nurse - you got the right stuff - now, just use it!
EMERGENCY DRUG REFERENCE
••• I'm going off the top of my head - so I may forget something - I'll add 'em if they come to me.

•••
These are the ones that are given in truly CRITICAL or RESUSCITATION situations:
Prefilled syringes that contain:
Lidocaine
Epinephrine
Atropine
Narcan
D50
Sodium Bicarb
Adenosine
Amiodarone
These are also critical, but usually require them to be reconstituted or drawn from a vial. These should not be diluted (other than recommended by mfg)
••• ALSO THESE SHOULD BE LABELED IN THE SYRINGE ••• HIGH RISK MEDS! •••
Etomidate
Anectine/Succinylcholine (or ANY PARALYTIC)
Norcuron/Vecuronium (or ANY PARALYTIC)
Additionally, these medications when given in doses for intubation/sedation following intubation and may be higher than what you give for other indications - in this case I label the syringe AND administer with a flowing IV fluid.
Fentanyl (doses as high as 1 MILLIGRAM have been given)
Ketamine
Versed
Ativan
Morphine
After you get past the meds listed above - you get into the "everyday" IV meds that your doc's give on a regular basis.
I have found, as a rule:
Morphine
Demerol (not as often now vs. 5 years ago - thankfully

)
Dilaudid
Toradol
Phenergan
Zofran
Kytril
Benadryl
Solumedrol
Solucortef
Decadron
Digoxin
Regular Insulin
Pepcid
Lasix
Protinix
Valium
Ativan
Beta Blocker du Jour
Cardizem
Labetalol
Heparin
Your "list" may vary. Learn your more common drugs that you use. This knowledge alone will be so valuable.
I always draw the ordered medication into the most accurate syringe for the ordered dose. I then draw another syringe of 10 or even 20 ml of NS. Take the NS syringe and then discard the amount (that equals the ordered drug dose) of NS that I will replace with the ordered drug dose from the other syringe - I then add my drug ordered to the NS syringe - I label and then administer via IV.
It may sound complicated, but it is really easy with a little planning/practice. And since I always do this - I just keep supplies at hand and stay prepared. For instance giving 40 mg of Lasix in 4 ml. I pull 16 ml of NS in a 20 ml syringe, add my 4 ml Lasix from the other syringe and then I administer.
I NEVER draw saline and then try to draw out a desired dose from a vial - too much of a chance of error if the vial contains more drug than you are ordered to give. The best way to reduce a chance for error is to do the same thing, the same way - each and every time.
This practice helps to insure that my patients will have their veins for another day. This practice can also work well on medication that must be given over time, it is easier to give 20 ml over 2 minutes than to try and give 2 ml over 2 minutes. I can also put the syringe on the pump (if your facility has that option) if needed.
But, check your facility guidelines - they may have specific ways that you must do it. This is just my way. And I have never had an error or infiltration incident from this method.
Just remember to always look up meds that you are not familiar with - also, any dose that seems "odd" should alert you to look up the med and confirm it with the MD.
Remember, once you push a drug - you can't pull it back. So be certain. Be deliberate. Be prepared.
Feel free to email me with any questions. I'd be glad to help if I can.
Relax, breathe. You and the patient will be fine.
Everyone starts at the beginning - and you want to do a great job! And that alone is a big part of successful nursing practice!
Practice SAFE!