Medical prescription: 250 ml 5% D/W to infusion over 10 hours. Drip fac-
tor 60.
Total fluid = 250 mL(cc)
Drip factor = 60 gtts/min
Infusion time in minutes = 600 min
Heparin infusion
Heparin is a medication that inhibits the formation of platelets and can be admin-
istered either as a subcutaneous injection or as a continuous intravenous infu-
sion. The proper dose of heparin is always calculated using either the formula
method or the ratio-proportion method.
Example: Medical prescription: Heparin 7500 Units SC
Available Heparin 10,000 Units per mL
Using the formula method:
Summary
The dose specified in a medication order may not be the same dose for the med-
ication that you have on hand. Therefore, you must calculate a new dose that is
proportional to the prescribed dose.
All doses are calculated using the metric system. You must be able to convert
within the metric system and convert between household measurements and
metric because patients are likely to self medicate using household measure-
ment—such as a teaspoon—rather than using metric measurements.
Converting between metric units is performed by moving the decimal to the
left or right depending on whether you are moving from a smaller metric unit to
a larger metric unit or vice versa. Converting between household measurements
and metric is achieved by multiplying or dividing using a conversion factor. This
depends on whether you are converting from household measurements to metric
or vice versa.
7500
10 000
75
units
unitsmL mL
,×=.
250 60
60015 000
600mL gtts / min
minutesmL
min25 gtts / minute×
==,CHAPTER 7 Dose Calculations^121