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

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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

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