PLEASE! Help with Med-Math problem..

[Tiffie1210]

I just took my med math test, for second year students we are required to get 100%. I had trouble with these two problems, could someone show me the simpliest way to solve them.. Thanks in advance

1. Dr order erythromicin 500 mg IVPB every 6 hours. Available to the nurse is 250 mL of NS with 0.5 G of erythromicin to infuse over 90 minutes. IV tubing delivers 12 gtt/mL. How many gtts min?

2. Dr order administer 1000 units heprin I.V every hour. Solution available is 25,000 units of heprin in 500 mL D5W. The administer set is microdrip (60 gtt/mL). Calculate gtt/min.

[gumby1411]

I set my solution up using dimensional analysis (remember chemistry?). It doesn't make sense to everyone, but this is how it works for my brain. I hope it helps.

1. 500mg/90 min x 1 g/1000mg x 250 mL/0.5 g x 12 gtt/1 mL = 33.3 = 33 gtt/min

2. 1000 units/1 hr x 500 mL/25,000 units x 1 hr/60 mins x 60 gtt/1 mL = 20 gtt/min

(It makes more sense if you write it out by hand)...

[Tiffie1210]

Thanks so much! This is what I got just did the problem a little different wanted to see if I was correct.

[myty23]

I got 33 on the first one too, but I just divided 250 ml by 90min and multiplied that by the 12gtt/min and got 33

[myty23]

2. Dr order administer 1000 units heprin I.V every hour. Solution available is 25,000 units of heprin in 500 mL D5W. The administer set is microdrip (60 gtt/mL). Calculate gtt/min.

Dose: 1000 units

_______________ x 500ml = 20ml

Have: 25000 units

20 ml/hr x 60 gtt/ml

_________________ = 20 gtt/min

60min