IV Math Calculations

[js2016]

Can someone tell me if I am calculating this right? Here is the problem, as well as my work:

Order: 0.9 g Ampicillin IV q6h to be diluted in 75 mL of D5W and infused over 30 minutes

Available: 2 g Ampicillin, which when reconstituted in NS gives a total of 10 mL

What flow rate should the pump be set at?

1) Finding Amount to Administer:

[2 g / 85 mL] = [0.9 g / (x) mL] --> x = 38.25 mL

2) Finding Total Volume:

75 mL + 10 mL = 85 mL ***Is the 10 mL even added to the total volume?

3) Finding Flow Rate:

[38.25 mL / 30 min] x [60 min / 1 hr] = 2295 mL / 30 hr = 76.5 mL/hr

[NICUismylife, ADN, BSN, RN]

Step 1 is incorrect. You need to add 0.9g to 75ml. Do not add the full 2g and then only administer part of it. Find out how many ml make up 0.9g. Then add that amount to 75ml. Then figure out the flow rate based on that figure.

[js2016]

What's throwing me off is the extra 10mL, and I cant seem to find an explanation on it in my book. ...So do I find how many of the 10mL's will equal 0.9g? Like this:

[2 g / 10 mL] = [0.9 g / (x) mL] = 4.5 mL

Is that what you mean? Then:

75 mL + 4.5 mL = 79.5 mL

And flow rate would then be:

[79.5 mL / 30 min] x [60 min / 1 hr] = 4770 mL / 30 hr = 159 mL/hr

[NICUismylife, ADN, BSN, RN]

Yes. Then add that amount to the 75ml. That will give you the total volume to be infused. Then you can calculate the flow rate.

[js2016]

Thank you SO much for the clarification! :)