Ordered: Lasix 40 mg IV push over 1 minute. Available: 80 mg in 1 mL.

How much will you draw up?

Ordered
————  x Volume of Liquid You Have = liquid required pushed over 1 minute
Available

40 mg
———— x       1 mL        =      0.5 mL     pushed over 1 minute
80 mg

To make math easy we know that the available dose is 80 mg in a 1 mL solution.

That would mean that you have 40 mg in 0.5 ml solution

(half of 80 is 40 and half of 1 is 0.5).

Furthermore, you would have 20 mg in 0.25 ml (half of 40 is 20 and half of 0.5 is 0.25 and so on….

(This last equation is not needed for this problem, I just wanted to show simple math)

I am not trying to insult anyone’s intelligence but sometimes we get wrapped up in what formula we need when the answer really is right in front of us using basic math.

Ordered: Polycillin 2 gms IV Q8 Hours in 500 ml normal saline bag.

Infuse over 4 hours

Tubing drop factor = 10 drops per ml (gtts/ml)

Amount of Fluid x Drops Per ML (gtts/ml)
—————————————————-
Time (60 minute intervals)

500 ml x 10 Drops Per ML (gtts/ml)                  5000
—————————————————-      =  —————    =    20.8 (21 gtts/min)
4 hours x 60 mins =  (240)                               240

** The time of infusion is always calculated by 60 if it is in hours**

But what if the time to infuse is less than 1 hour?

Let’s take a look at Example 3…..

Ordered: Polycillin 2 gms IV Q8 Hours in 50 ml normal saline bag.

Infuse over 20 min.

Tubing drop factor = 10 drops per ml (gtts/ml)

Amount of Fluid x Drops Per ML (gtts/ml)
———————————————————-
Time (60 minute intervals)

50 ml x 10 Drops Per ML (gtts/ml)                    500
—————————————————- =        ————–    =     25 gtts/min
20 minutes                                                          20

** If the time is less than one hour then we just divide by the minutes ordered. In this case 20 minutes.**