Week Four: Med Calculations continued

Question 1

What information will an injectible medication label give you?

Answer 1

• total dosage per container
• dosage per volume
• fluid medication is diluted in
• route of injection
• expiration date
• manufacturer and drug lot #

Question 2

How can you calculate the amount of medication you are administering?

Answer 2

desired
———- X vehicle = Dosage
have

Question 3

What if a drug is only stable for a short period of time after mixing?

Answer 3

some injectible or IV medications are packed in powdered form and are reconstituted using a diluent before administration

• single dose vial vs multi-dose vial
• concentration of solution, date and time of reconstitution and RN initials
• directions for dilution are included on the label

Question 4

Primary IV Infusion

Answer 4

run continuously through the main IV tubing set

Question 5

IV PIggyback Infusion

Answer 5

connected to the main IV tubing intermittently via a shorter IV tubing set

Question 6

How are IV infusions regulated?

Answer 6

administering fluid via an infusion pump that regulates mL/ hr or by counting drops per minute in the drip chamber

Question 7

How do you calculate mL/ hr?

Answer 7

Total Volume of Infusion in mL (TV)
————————————————— = mL/ hr
Total Infusion time in Hours (TH)

Question 8

mL/ hr example:
The HCP orders 1000mL of NS to infuse over 10 hours. How many mL/hr will the nurse set the volumetric infusion pump to infuse at?

Answer 8

1000mL/ 10 hr = 100mL/ hr

volume to be infused in mL/ total infusion time in hours = mL/ hr

Question 9

Drop Factor

Answer 9

the number of drops (gtts) that equal one mL

• regulated by adjusting the roller clamp on the IV tubing
• tubing specific drop factor found on the packaging
• Macrodrop sets can be 10, 15, or 20 gtts/ mL
• Microdrop sets are always 60 gtts/ mL

Question 10

How would you calculate the IV flow rate using drop factor?

Answer 10

Amount of fluid (in mL) X gtts/ mL (IV set)
———————————————————- =
Hours to Administer X 60 (min per hour)

Question 11

What does the nurse do if the flow rate is not a whole number?

Answer 11

flow rates can be rounded because they are not exact dosages

Question 12

Rules for rounding

Answer 12

carry decimal out to one hundredths place and round back to tenths place

• any number less than 5 is rounded down
• any number equal to or greater than 5 is rounded up

Question 13

Drop Factor Example:
The HCP orders Liter D5W to infuse over 6 hours. The drop factor of the tubing is 15 gtts/mL. How many mL/hr would it infuse at and what is the infusion drop factor?

Answer 13

convert 1 Liter to 1000mL
Calculate mL/hr:
1000mL/ 6 hours = 166.66 or 167 mL/hr

1000mL X 15 gtts/mL
————————— = 15000/ 360 = 41.66 or 42 gtts/mL
6 hrs X 60 minutes

Question 14

Administering IVBP Medications

Answer 14

add the medication to the bag as stated in the order
-in this case, add to 50 mL NS
-mark bag with:
>name and dose of medication
>date and time
>your (nurses) initials
-attach the mini bag tubing to the IV medication bag and connect it to the infusion port on the main IV tubing–> adjust infusion rate to infuse med bag over prescribed time

Question 15

How would the nurse calculate the Drop factor of this IV piggyback med?
Order: Cefoxin 1 gm in 50 mL NS over 30 min Q6H IV tubing drop factor is 15 gtts/ mL

Answer 15

hours X 60 min per hour

50 mL X 15 gtts/mL

0. 5 hr X 60 (or 30 minutes)

750/30 = 25 gtts/min