Working out med calculation for drugs that are mixed with N/S through syringe.

[AussieKylie]

hi there

first, my previous user name was sn_2b_rn and now got it changed to rnkylie because now i am a gradrn. anyways, just wanting some help, clarification on how to work out a calculation formula that requires a drug (heparin or insulin) mixed with n/s that is being infused via syringe infusion. i am trying to find this calculation that i did during nursing labs, cannot find it. i do remember a syringe that can be used was either 20ml or 50ml and the rest to make it up to that amount was the drug component but not sure how to work out this calculation.

can anyone help. i feel i just need to know it before i go into start my grad program in which is coming up.

thank you

[AussieKylie]

[color=darkslategray]

[color=darkslategray]i think i have got it now. i found a calculation example and it helped.

[color=darkslategray]for anyone else who wants to know:

10,000units of heparin have been added to 50mls 0.9% n/s for infusion via a syringe driver. the dose prescribed is 1100units/hr. calculate rate of infusion in mls/hr.

sr>>>>

1100units x 50mls = 5.5ml/hr

10000units 1

so because 10000units = 1ml we need to make up the syringe to 50mls, so i hope this part is right please correct me if i am wrong, that 1ml of heparin is added to 49mls of n/s

:paw: :chair:

[Daytonite, BSN, RN]

Yes, you are right. Using the "dose desired divided by the dose on hand multiplied by the amount" formula, you determine the infusion rate to be 5.5 ml/hr. To actually make this 50mL solution you would need to consider the amount the 10,000 units of Heparin is in and add enough 0.9% N/S to get 50mL.

I wasn't understanding exactly what you were asking in your original post, so I didn't know how to respond to it. It might be a common language usage of your country that had me puzzled as to what you were asking.

In any case, the general formula you came up with is one I use all the time for stuff like this. It's very practical. To use it in the manner you were originally asking, you merely need to plug the known numbers you have to work with. For example, if the doctor changes the dosage to 900 units/hr. (and these dose changes on heparin will happen frequently), you would merely change the infusion rate of the current syringe infuser. Using the same good old formula you would get:

900 units/10,000 units x ___ mL left in the syringe = the new infusion rate

or, mix a new syringe (probably the safest thing to do) and pull up 10,000 units of Heparin into a 50 mL syringe and continue to fill it to a total of 50 ml with your 0.9% N/S so that your new infusion rate will be:

900 units/10,000 units x 50 ml = 4.5 mL/hr

It won't be long before you'll be able to rattle off these calculations like you've done them all your life because you will use them so much.

[AussieKylie]

sorry daytonite, it was probably my laziness in trying to explain it, i didnt explain it properly. when i need to clarify something its usually a straight away type it. thanks for confirming that i am on the right track, appreciate it