if the order reads, "give .3 mgms. of drug z and 65 mgms of drug n" how much fluid will you have in your syringe? the labels read drug z, 110.4 mgms 1/2 cc and drug n, 0.075 g in 1 cc.
dose #1 (drug z) desired: 0.3 milligrams (mgm)
dose #2 (drug n) desired: 65 milligrams (mgm)
dose #1 (drug z) on hand: 110.4 milligrams (mgms) per 1/2 cubic centimeters (cc) (0.5 cc)
dose #2 (drug n) on hand: 0.75 grams (g) in 1 cubic centimeter (cc)
conversion factor: 1 gram = 1000 milligrams
the set up, by dimensional analysis is:
(0.3 mgms/1 [dose desired of drug z] x 0.5 cc/110.4 mgms [dose on hand of drug z]) + (650 mg [dose desired of drug n] x 1 cc/0.075 g [dose on hand of drug n] x 1 g/1000 mg [conversion factor]) = 0.15cc/110.4 + 8.67cc/75
now, there are a couple of things you can do with this answer. you can divide each term out into an answer and then add the result together. you could find the common denominator of the two terms and add them together to get the final answer. the difference between getting the two answers each way may or may not make a difference.
0.15cc/110.4 + 8.67cc/75 = .00135cc + 0.1156cc = 0.11695cc = 0.1cc (final answer rounded off to tenths)
0.15cc/110.4 + 8.67cc/75 = 11.25 + 957.168/8280cc = 968.418/82875cc = 0.1168cc = 0.1cc (final answer rounded off to tenths)
i have to say, however, that these dosages would be almost impossible to draw up in clinical practice. are you sure you copied the problem correctly?
an iv was started at 9:00am with orders to infuse 500ml1 over 6 hrs. at 12 noon the iv infiltrated with 350ml left in the bag. at 1pm the iv was restarted. the set calibration is 20 gtt/ml. calculate the new flow rate to deliver the fluid on time.
ok, first off, you need to calculate how many ml of solution were delivered from 9am to noon, and then how much of the 500 ml need to be infused if you want to finish the infusion before 6 hours have elapsed since 9am (9am + 6 hours = 3pm)
500ml - 350ml = 150ml left to infuse
from 1pm to 3pm = 2 hours, so you have 2 hours to infuse 150ml with an infusion set that delivers at 20gtts (drops) per ml. the new flow rate at ml/min
will be. . .
drip factor of iv tubing:
1 hour/60 minutes
150ml/2 hours (dose desired) x 1 hour/60 minutes (conversion factor) x 20 gtts/1 ml (drip factor of iv tubing) = 25 gtts/minute (new iv flow rate)
there are more examples of dosage calculation problems worked out on this sticky thread that you can study: