Just starting dosage calculations

[Avictorious]

Hi everyone! I'm just starting with dosage calculations and I'm a little flustered to say the least. This is one of my practice problems:

The physician orders 1000ml of 0.9% of sodium chloride IV over 60 ml/hr. On hand is tubing with a drip factor of 10 gtt/ml. What drip rate would you use?

I think the formula is [amt to be infused x drip rate]/duration of infusion. I'm not sure what to put for duration of infusion or how to translate 60ml/hr. Would I do 1000ml/60 min?

[203bravo, MSN, APRN]

think of it a little differently and see if it helps you --- for this problem the 1000 mL is a distractor.

you are wanting to give 60 mL in an hour (60 mL/hr)

the tubing drop factor is 10 drops for every mL (10gtts/mL)

how many drops per minute are you wishing to give? (gtts/min)

[Avictorious]

So if I change it around and do

(60ml x 10gtt/ml)/60min = 10gtt/min

does that sound right? The 1000ml was certainly a distractor and I was using that as the total amount infused

[203bravo, MSN, APRN]

excellent work... just remember the hardest part of med math is figuring out exactly what the question is asking and figuring out what the distractors are. It's only natural to think that if information is included in the problem then it must be important and thus need to be used somehow in the calculation.. this is just not true :)

[IVRUS, BSN, RN]

Hi everyone! I'm just starting with dosage calculations and I'm a little flustered to say the least. This is one of my practice problems:

The physician orders 1000ml of 0.9% of sodium chloride IV over 60 ml/hr. On hand is tubing with a drip factor of 10 gtt/ml. What drip rate would you use?

An easier way to look at this is to remember a few variables:

Macro gtt tubing comes in either 10gtts/ml

15gtts/ml

20gtts/ml

And they vary depending on the manufacturer. Baxter may make a 10gtt set, while Travenol may make a 20gtt set.

Then remember, mini or micro set is 60 gtts for one ml to infuse.

Now, once you have that, know this: The first thing you need to have in order to get drops per minute is flow rate. FLOW RATE is expressed as mls per hr. In your problem the flow rate is given to you.. YAY...(60)

Now, think of the IV tubing. It tells you that you have a 10gtt/ml set. Now think of the clock: Visualize it in your mind. How many 10 second increments go into one minute? 6 right? So, divide your flow rate by 6 and you have gtts per minute. (A=10)

Now, what if your IV tubing was 15? There are 4 fifteen second increments in a minute,

so 60/4 = 15.

20gtts tubing? 60/3 = 20 gtts per minute.

So really, it is so easy, pick out the flow rate, then divide by its appropriate equivelant and you have gtts per minute.

[Avictorious]

Thank you both!