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Discussion

Drip Rate Help

Hey,

So I'm new to the forums as far as posting but I always see good advice so I figured I'd take advantage of it. This drip rate problem was on a recent worksheet and I am not coming up with the same answer as what the instructor says. To calculate the problem I used what was ordered ( the 1 gram every 6 hours to infuse for 40 minutes ) for the instructors answer it appears she used the what came prepared ( the 100ml for 40 minutes ) Here is the problem... Let me know how you would solve it and why?

Order: ampicillin 1 gram every 6 hours IV piggyback to infuse over 40 minutes. The ampicillin comes prepared in 100 ml D5W. Your patient has an IV of D5W infusing at 125ml/hr. drop factor of 20.

Calculate the drip rate (gtts/min) for the ampicillin infusion.

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    • Featured Replies

    • Expert

    OK so show us what you came up with and we'll see where you went wrong. Yes you are giving the 1gram of ampicillin but it COMES IN a 100ml bag.The drug and the number of grams is irrelevant.All you need to know is how many mls in the bag.Figure out the rate you would run it at (how many mls an hour) Then how many mls a minute. Then how many drops a minute.

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    • Author

    Well I used the 1 gram and I guess thought way to much into the problem. I figured that 1 gram could be equal to either 1 liter or 1000 ml. I just figured that I should use what was ordered.

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    • Expert

    You need to know your conversions. Gram is a weight measurement.Litre(1000ml) is a volume measurement. One cannot equal the other.Yes the 1 gram was ordered but it comes in 100ml of fluid. That's the only thing you need to know. How much volume is in the bag.

    So you have 100ml to be absorbed in 40 minutes.100 divided by 40 is 2.5.So 2.5 mls a minute.The drop factor is 20 gtts/min.20 x 2.5 = 50. You would run it at 50 gtts a minute.

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    Antibiotics are in power form which is then mixed into fluids like NS or D5W. As loriangel stated, you cannot equate units of mass for solids to units of volume for liquid. Once you know that 100ml of fluid contains the ordered amount of 1g, you must use the volume in drip calculation. Weight becomes irrelevant.

    On a side note, 1g of water = 1ml of water at 4 degrees C. (Temperature is important as density changes with different temp.) That means one liter equals 1kg. Nice to keep that in mind as a reference.

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    • Author

    Thanks so much for all the help. Definitely eared some things up. Just starting on all the drug calc so any help is appreciated.

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    Well I used the 1 gram and I guess thought way to much into the problem. I figured that 1 gram could be equal to either 1 liter or 1000 ml. I just figured that I should use what was ordered.

    That's where you made your mistake. 1g of ampicillin does not equal 1 liter. If you read the problem, it tells you that your medication comes prepared in 100 mL. That's what you need to figure out the rate. 1g is irrelevant.

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    any easy way i always use is. this: volume to be infused in ml X drip factor divided by number of minutes to be infused.

    so... 100ml X 20 = 2000

    2000 divided by 40 = 50 gtt/ml

    just remember that formula.

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    Remember when you took chemistry? When you weighed things, it was on a scale. When you measured liquids, it was in a graduated cylinder. Drops are not a measure of weight, they're a measure of liquid. Never forget that. It's one reason you had to take chemistry for nursing school. :)

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    • Expert

    Know your conversions

    The Short List 1 cup © = 8 ounces (oz)

    1 dram (dr) = 60 grains (gr)

    1 dram (fl dr) = 60 minims

    1 gallon (gal) = 4 quarts (qt)

    1 glass = 8 ounces (oz)

    1 grain (gr) = 64.8 milligrams (mg)

    1 gram (g) = 15.43 grains (gr)

    1 inch (in) = 2.54 centimeters (cm)

    1 kilogram (kg) = 2.2 pounds (lb)

    1 liter (L) = 1.057 quarts (qt)

    1 milliliter (mL) = 16.23 minims

    1 minim = 1 drop (gt)

    1 ounce (oz) = 2 tablespoons (tbsp)

    1 ounce (oz) = 8 drams (dr)

    1 ounce (fl oz) = 29.57 milliliters (mL)

    1 pint (pt) = 16 ounces (oz)

    1 pound (lb) = 16 ounces (oz)

    1 quart (qt) = 0.946 liters (L)

    1 quart (qt) = 2 pints (pt)

    1 tablespoon (tbsp) = 3 teaspoons (tsp)

    1 teacup = 6 ounces (oz)

    1 teaspoon (tsp) = 4.93 mL

    The Long list

    1 central = 45,359 grams (g)

    1 centimeter (cm) = 10 millimeters (mm)

    1 cubic centimeter (cc) = 1 milliliter (mL)

    1 cup © = 8 ounces (oz)

    1 drachm = 3.55 milliliter (mL)

    1 dram (dr) = 60 grains (gr)

    1 dram (fl dr) = 60 minims

    1 gallon (gal) = 4 quarts (qt)

    1 gill = 4 ounces (oz)

    1 glass = 8 ounces (oz)

    1 grain (gr) = 64.8 milligrams (mg)

    1 gram (g) = 1,000 milligrams (mg)

    1 gram (g) = 1,000,000 micrograms (mcg)

    1 gram (g) = 15.43 grains (gr)

    1 hand = 4 inches (in)

    1 inch (in) = 2.54 centimeters (cm)

    1 kilogram (kg) = 1,000 grams (g)

    1 kilogram (kg) = 2.2 pounds (lb)

    1 liter (L) = 1000 milliliters (mL)

    1 liter (L) = 1.057 quarts (qt)

    1 meter (m) = 1,000 millimeters (mm)

    1 meter (m) = 100 centimeters (cm)

    1 milligram (mg) = 1,000 micrograms (mcg)

    1 milliliter (mL) = 1 cubic centimeter (cc)

    1 milliliter (mL) = 15 drops (gt)

    1 milliliter (mL) = 16.23 minims

    1 minim = 1 drop (gt)

    1 ounce (fl oz) = 2 tablespoons (tbsp)

    1 ounce (oz) = 20 pennyweights (dwt)

    1 ounce (oz) = 24 scruples

    1 ounce (oz) = 31.1 grams (g)

    1 ounce (oz) = 480 grains (gr)

    1 ounce (oz) = 8 drams (dr)

    1 ounce, fluid (fl oz) = 29.57 milliliters (mL)

    1 palm = 3 inches (in)

    1 pennyweight (dwt) = 24 grains (gr)

    1 pint (pt) = 16 ounces (oz)

    1 pint (pt) = 4 gills

    1 pound (lb) = 16 ounces (oz)

    1 pound (lb) = 350 scruples

    1 quart (qt) = 0.946 liters (L)

    1 quart (qt) = 2 pints (pt)

    1 scruple = 20 grains (gr)

    1 stone = 0.14 cents

    1 tablespoon (tbsp) = 3 teaspoons (tsp)

    1 teacup = 6 ounces (oz)

    1 teaspoon (tsp) = 60 drops (gtt)

    1 teaspoon (tsp) = 4.93 mL

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    • Expert

    But many things are rounded up. 1 teaspoon is 5 mls and and ounce is 30mls.

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