give bretylium 1 gram in 250 ml d5w at 2mg/min. drop factor=15 gtt/ml. calculate the volume per hour.
: 2 mg/1 minute
dose on hand
: 1 gram/250 ml
: 1 gram = 1000 mg
: 60 minutes = 1 hour
you want to end up with ml/hour
. the drip factor of the iv tubing is a red herring (distracter information) in calculating the volume per hour this iv will run and is not necessary information in determining the answer:
2 mg/1 minute (dose desired) x 60 minutes/1 hour (time conversion factor) x 250 ml/1 gram (dose on hand) 1 gram/1000 mg (conversion factor) = 30 ml/hour (dose to give, or volume per hour)
give insulin 100 units in 1000ml of ns at 6 units/hour. calculate the volume per hour.
dose desired: 6 units/hour
dose on hand: 100 units/1000 ml
6 units/1 hour (dose desired) x 1000 ml/100 units (dose on hand) = 60 ml/hour (dose to give, or volume per hour)
i worked these by dimensional analysis which is, i think, is a much more efficient way to deal with problems, particularly when the information starts to get more complicated and involve more factors. still, the basic formuladose desired divided by the dose on hand times the amount the dose on hand comes in gives you the amount (or dose) to give.
that formula will never steer you wrong. you only have to determine which terms are which. it could have easily worked for the second problem:
6 units (dose desired)/100 units (dose on hand) x 1000 ml (amount the dose on hand comes in) = 60 ml
there are tutorials on medication calculation plus weblinks to sites that have practice problems on post #3 of this sticky thread of the student forums: http://allnurses.com/forums/f50/nurs...ad-264395.html
- the nursing math thread
(in the general nursing student discussion forum). several of the tutorials are really good and you should take advantage of them. you can also see a whole bunch of problems worked out on this sticky thread:
- dosage calculations
(in the nursing student assistance forum).