Quote from deecole4
A pt weighing 133 lbs is to receive 22 units/kg/day, to be delivered over 2 hours. The solution is 500 units/66ml and the drop rate is 15 gtts/ml. How many gtts/min should the pt receive?
Begin by recognizing that, while you have mixed units, you only have a few physical quantities to deal with:
mass/weight (lbs, kg)
time (days, mins, hrs)
drug quantity (units)
Make sure that you're comfortable converting from one to another.
Next, focus on the order... 22 units/kg/day given over 2 hours.
Now focus on the patient... 133 lb
Now you can determine how many units the patient will get by converting the pt's weight in lb to weight in kg.
Now that you know how much the pt is to receive, you need to figure out what volume of the medication contains that quantity of units.
Utilizing 500 units per 66 mL and the units required, you can calculate the volume.
Now that you know the volume, you need to determine the rate... remember, it's ordered over 2 hours.
Now you have a volumetric rate in mL/hr... and in the real world, you'd be done... you'd simply program your pump with the volume and the rate, push start, and check that it's flowing.
In your problem, though, you're looking for a minute-rate, not an hour-rate so convert the mL/hr to mL/min.
Now, you have the volumetric rate per minute but that doesn't tell you how many drops per minute. For that, you need to drip factor which just quantifies how large are the drops... the common drip factors are 10, 15, 20, and 60... in each case it simply says how many drops are required to make 1 mL.
Your problem states 15 drops/mL so now you can convert your volumetric rate per minute to a drip rate per minute.
Once you have worked through this, you can spot check your answers below.
Amount required: 1330 units per day
Volume: 175.6 mL
Volumetric rate: 87.8 mL/hr
Drip rate: 22 drops per minute