For example, the prescriber might order Demerol 45mg IM prn to alleviate
the patient’s pain. The Demerol label states 75 mg/mL. This is the dose you have.
The nurse must calculate the number of milliliters that should be administered
to the patient.
Using the basic formula here’s the calculation:
CALCULATING THE IV FLOW RATE FOR CONTINUOUS
OR INTERMIT TENT (PIGGYBACK) INFUSIONS
The IV flow rate is the number of drops of the IV fluid that the patient receives
in a minute. The intravenous order directs the nurse to administer a specific vol-
ume of fluid to the patient over a specific time period. It is the nurse’s responsi-
bility to calculate the number of drops per minute that is necessary to infuse the
IV fluid into the patient over the prescribed time period.
In order the calculate the drip rate you need to know:
- The volume of fluid that is to be infused. This is found in the medication
order in milliliters (mL) or cubic centimeters (cc). - The amount of time over which the infusion is to take place.
- The drip factor, which is specified on the IV tubing that is used for the infusion.
Here’s how to calculate the drip rate. It is important to remember that although
we use milliliters in the following examples, you can substitute cubic centi-
meters (cc) for milliliters (mL) if cc is specified in the order. Always express
gtt/min in whole numbers. Always carry out to the tenth then round to nearest
whole number. If a volumetric pump is used to deliver the IV fluid, then you’ll
need to use cc per hour.
Total fluid multiplied by drip factor and divided by the infusion time in
minutes.
45
75
1
45
75
1
45
75
6
mg
mg
mL
1
A
mL
1
A
mL
mL
×=
×=
=.
D
H
×=VA
(^120) CHAPTER 7 Dose Calculations