Medication calculation question

Nursing Students General Students

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Specializes in Anesthesia, CCRN, SRNA.

I'm stuck on a homework problem and hope some of you who have had this before can help me work this one out.

The patient is to receive 5mcg/kg/min of dopamine. The drug is supplied in 200mg in 250ml of NS. The patient weights 132lbs

Using a microdrip set how many drops per minute (gtts/min) should be delivered.

Using an IV pump, how many ml/hr should be delieverd.

Thanks in advance if you can help me!

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Specializes in Family Nurse Practitioner.

What do you have so far?

0 Votes
Specializes in Anesthesia, CCRN, SRNA.

.005gm/kg * 60kg = 0.3mg/min

0.3mg/200mg *250ml = 0.375ml/min

microdrip - 60gtt/ml

60gtt * 0.375ml = 22.5 gtt/min

Just a guess so far

0 Votes
Specializes in Family Nurse Practitioner.
.005gm/kg * 60kg = 0.3mg/min

0.3mg/200mg *250ml = 0.375ml/min

microdrip - 60gtt/ml

60gtt * 0.375ml = 22.5 gtt/min

Just a guess so far

As far as I can tell (someone please correct me if I'm wrong) you are right on. The beauty of using a micro drip is that the gtt/min = ml/hr so the mls per hour would be 22.5 and I would do the gtts/min as 23. Good job!

0 Votes
Specializes in ICU/PCU/Infusion.

132 lbs x 1kg x 5mcg x 60mins x 1mg x 250 mls

1 2.2 lbs kg/min 1 hr 1000 mcg 200 mg

9,900,000 = 990 = 22.5 mls/hr

(using dimensional analysis)

440,000 44

0 Votes
Specializes in ICU/PCU/Infusion.

well shoot! sorry, I underlined all the numerators, and it won't look right on the screen when I post it. hopefully, you get the idea.

:uhoh21:

0 Votes
Specializes in Ortho, Neuro, Detox, Tele.

it does work out to 22.5 and since it's an IV, you gotta round to the whole number.

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Specializes in med/surg, telemetry, IV therapy, mgmt.

leslasic. . .this program won't print out fractions the way you did them. your set up is correct, however.

drugreptonurse. . .i set this up by dimensional analysis. however, i also used the formula dose desired divided by dose on hand to help me do the set up. it becomes a complex fraction of fractions in the numerator and denominator. with dimensional analysis i always write off to the side what labels i want to end up with. in this case, i want to end up with drops per minute, where drops are in the numerator and minutes in the denominator.

5mcg
/
1kg
(dose desired)
x
1
/
1 minute
(rate desired)
x
250ml
/
200mg
(dose on hand)
x
132lbs
/
1
(patients weight, given information)
x
1mg
/
1000mcg
(conversion factor)
x
1kg
/
2.2lb
(conversion factor)
x
60gtts
/
1ml
(drip factor of iv tubing to be used)
=
9,900,000gtts
/
440,000 min
(after canceling out all the repeated labels in the numerators and denominators and doing the actual math calculation)
=
22.5gtts
/
1min
(after simplifying)
=
23gtts
/
min
(after rounding off)
.

the problem is still not finished. since microdrip tubing delivers 60gtts per minute, or one drop per second, the rate per minute is the same as the rate per hour. so, you would set the iv pump at 23ml / hour.

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