IV DRUG
CALCULATIONS
Help with Math Assignment/ Sample
problems
IV mL per hour (Hourly Rates)
■ IV in mL per hour is required for setting the hourly rate on IV pumps. All IV
pumps require an hourly rate. The total VOLUME amount should be divided
by the time in hours and answer will be in mL/h.
■ See slide for figuring out mL/h if minutes less than or slightly above an hour
are given.
■ Sometimes the total VOLUME amount and the hourly rate are given. Then
divide the VOLUME amount by the hrly rate to figure out how many hours the
infusion lasts.
IV Drop Factors/ Flow Rates
■ A drop factor is how many drops (gtts) per mL a set of IV tubing delivers which
depends on its size. This is important when IVF is given without an IV pump.
We need to calculate how many drops to administer per minute to make sure
the IVF infuses at the proper rate. An analogy is to think about filling a bathtub
at a certain rate by counting drops from the faucet. The microdrip tubing rate
delivers 60 drops per mL (60 drops = 1 mL). Macrodrip tubing usually delivers
either 10, 15, or 20 drops per mL. When we choose the answer for the math
problem, think about a realistic rate to count per minute. Just like when we are
checking a pulse, it is difficult sometimes if it is really fast; we want to pick a
number we are able to easily count for that minute to make sure the drop rate
is correct to deliver the IVF in the proper time. For example, it would be easier
to count 40 drops per minute rather than 100 drops per minute. 100 drops
would be very fast and would be difficult to regulate with the IV clamp. The
nurse would use the regulator (rolling) clamp to adjust the drops per minute.
■ A part of a drop cannot be given so remember rounding rules (up or down) for
drops per minute. Also, most infusion pumps deliver in whole numbers, so
round mL to nearest whole number.
Sorry for my sloppiness. Let me
know if help is needed!