Tactics for Solving IV
Drip Rate Problems

DRAFT Version 1.1, 24-OCT-2006,
CLOates

For
orders stated with __VOLUME__ flow rates expressed in mL/hr or gtt/min,

If the problem is a
simple request for a flow rate (gtt/min or mL/hr),

find a flow rate (mL/hr) in the problem
statement and transform that flow rate into the required answer units (usually gtt/min) using the drop factor, if necessary;

else if the problem requires reconstitution or
dilution of medication

first, find the strength of the concentrate on the
label, as we did in Chapter 8, and calculate the amount of reconstituted medication
to be put into the IV bag; then, calculate the flow rate as above;

else if the problem asks for time to infuse

remember the “how
long to drive to Amarillo problem,”

4 hours = 240 miles * 1 hour / 60 miles; you’re consuming mL of
fluid instead of miles; the flow rate
will probably be given in gtt/min (not mL/min), so
you’ll have to convert the mL of fluid to drops (gtt)
using the drop factor and then apply the rate in gtt/min

end

For orders
stated with __WEIGHT__ flow rates (drug infusion rates) expressed in mg/hr, mcg/kg/min, mEq/hr, or Units/hr,

If the problem is a
simple request for a flow rate (gtt/min or mL/hr),

first, as a side calculation, calculate the
medication strength (concentration) __in the IV bag__ in mg/mL or mEq/mL or Units/mL;

then use the flow rate in mg/hr, mEq/hr, or units/hr as the starting factor;

if necessary, multiply the starting factor by
the patient’s weight in kg;

apply the medication strength calculated above as
a conversion factor to transform the weight units (mg, mEq,
Units) into mL;

convert the time units, if necessary to arrive at
mL/hr or gtt/min;

else if the problem requires reconstitution or
dilution of medication

first, find the strength (mg/mL, mEq/mL, or Units/mL) of the powder or concentrate on the
label, as we did in Chapter 8, and calculate the amount of reconstituted
medication to be put into the IV bag

next, calculate the flow rate, as above; that
is:

as a side calculation, calculate the
medication strength (concentration) __in the IV bag__ in mg/mL or mEq/mL or Units/hr;

then use the flow rate in mg/hr, mEq/hr, or units/hr as the starting factor;

if necessary, multiply the starting factor by
the patient’s weight in kg;

apply the medication strength calculated above
as a conversion factor to transform the weight units (mg, mEq,
Units) into mL; if required, apply the
drop factor to convert mL to drops (gtt)

convert the time units, if necessary to arrive at
mL/hr or gtt/min

end