Paramedic Med-Math:
There is actually a surprisingly small amount of math required in paramedicine, as many of our medications are set doses. Some, however, are based on weight and require a bit of calculation. We also need to know how to calculate for IV fluid volume and drip rate over time. I will provide a quick discussion on the basics of paramedic me-math.
Calculating for dose:
The most commonly used math is that of dosage based upon available quantity of medication. The basic formula is:
(Dose required / Dose available) x quantity = Dose given
In simplified terms:
(Want / Have) x quantity = Dose
So if I want to give 0.5mg of epinephrine and I have epinephrine available in a quantity of 1mg/ml:
(Want: 0.5mg / Have: 1mg) x 1ml = 0.5ml
This is the basic medication formula for any type of medication administration you may perform.
IV drip rate:
IV calculations are a bit more complicated at face value, but in reality we are performing relatively simple math. The formula to determine drip rate (gtt/min) is as follows:
(Volume of fluid / Time in minutes) x Drip factor of the tubing
So, if I want to give 250ml of fluid over 30 minutes with a 15 drop set:
(250ml / 30min) x 15gtt/min
=125 gtt/min
To determine how many drips er second that is, we divide by 60 seconds.
125 gtt/min / 60 seconds
= 2
Medication infusion rate:
If we are giving medications by IV infusion we use the formula:
(Desired dose in mg/min x 60 min/hr) / Drug concentration mg/ml
This formula is less commonly used by PCPs, but may be used by ACP providers.
Thats pretty much it. Not as complicated as it seems.
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