IV Calculations, Solutions, and Equipment
Calculate the amount of sodium chloride (NaCl) in 1000 mL NS.
0.9% = 0.9 g NaCl per 100 mL Solve: 0.9 g : 100 mL = x(g) : 1000 mL Answer: 9 g NaCl
Order: 20 mEq of potassium chloride to be placed in 1000 mL of fluid to be administered at a rate of 2 mEq of potassium chloride per hour.
1- Calculate the number of mL of solution needed to deliver 2 mEq of potassium chloride per hour. 20 mEq : 1000 mL = 2 mEq : x (mL) 20x = 1000 x 2 20x = 2000 x= 100 mL ** 100 mL of fluid needed to administer 2 mEq of potassium chloride per hour. 2- Determine flow rate (Drop factor: 15 gtt/mL) 100 (mL) X 15 (gtt/mL) gtt/min = -------------------------------- = 25 gtt/min 60 min **25 gtt/min would deliver 2 mEq of potassium chloride per hour from this solution
Basic principles for Calculating IV Flow Rate
1- Drops per minute are always expressed in whole numbers. Principles of rounding off are applied. Example: 19.5 gtt = 20 gtt 2- Carry division of the problem one decimal place to round to a whole number of drops
Steps to Calculating a Problem with an Unknown with the Formula Method
1- Take information given in the problem and place in the formula. 2- Place an x in the formula in the position of the unknown. If you're trying to determine time in hours, place x in the position for minutes; once you find the minutes, divide the number of minutes by 60 (60 minutes= 1hr) to get the number of hours. 3- Set up an algebraic equation so that you can solve for x. 4- Solve the equation 5- Label the answer in hours or mL for volume.
Calculating Total Infusion Time (Small Volume)
1. Calculate the mL/min 2. Divide the total volume by the mL/min to obtain the infusion time. The infusion time will be in minutes
Calculating Total Infusion Time When Rate in mL/hr Is Not Indicated for Large Volume of Fluid
1. Convert gtt/min to mL/min 2. Convert mL/min to mL/hr 3. Total number of mL to infuse --------------------------------------- mL/hr infusing at
Determine rate in gtt/min IV should be regulated. Order: D5W to infuse at 100 mL/hr. Drop factor: 10 gtt/mL
100 mL X 10 gtt/mL x (gtt/min) = -------------------------- 60 min 1000 x = ------- = 16.6 = 17gtt/min 60
Calculate the amount of dextrose in 500mL of D5W
5% dextrose= 5 g dextrose per 100mL Solve: 5 g : 100mL = x(g) : 500mL Answer: 500 mL of D5W contains 25 g of dextrose
Calculating Large Volumes of Fluid (mL per hour)
Amount of solution (mL) x (mL/hr)= ----------------------------------- Time in hours
Determining Infusion Times and Volumes
Amount of solution (mL) X Drop factor x (gtt/min) = ---------------------------------------------------- Time in minutes
Calculate infusion time for small volume
Calculate infusion time: An IV medication of 35 mL is infusing at 30 macrogtt/min. Drop factor: 15 gtt/mL 1. Calculate the mL/min 15 gtt : 1 mL = 30 gtt : x(mL) = 2 mL/min 2. Divide the total volume by the mL/min 35 mL divided by 2 mL/min = 18 minutes
Determine rate in gtt/min IV should be regulated. Order 1000 mL D5W to infuse in 8 hr. Drop factor: 20 gtt/mL
Calculate mL/hr : 1000 mL x (mL/hr)= ------------- x= 125 mL/hr 8 hr Calculate gtt/min : 125 mL X 20 gtt/mL x (gtt/min) = -------------------------- 60 min 125 x = ------- = 41.6 = 42 gtt/min 3
Points To Remember
Calculation of gtt/min can be done by using the formula method or dimensional analysis. Amount of solution(mL) X gtt factor Formula: x (gtt/min)= ------------------------------------------------ Time in min
Calculate infusion time (mL/hr not indicated) A client is receiving 1000mL of RL. The IV is infusing at 21 macrogtt/min (21 gtt/min). The administration set delivers 10 gtt/mL.
Change gtt/min to mL/min 10 gtt : 1 mL = 21 gtt : x (mL) = 2.1 mL/min Convert mL/min to mL/hr 2.1 mL/min X 60 min = 126 mL/hr Calculate infusion time 1000 mL -------------- = 7.93 = 7 hours 56 minutes 126
Determining volume: IV is regulated at 17 macrogtt/min. Drop factor = 15 gtt/mL. How much fluid volume in mL will the client receive in 8 hr?
Change minutes to hours: 60 minutes= 1 hr 8 hr x 60= 480 minutes x (mL) X 15 gtt/mL 17 macrogtt/min = ------------------------------ 480 min 15x = 17 x 480 15x = 8160 x= 544 mL
Calculate the amount of dextrose and sodium chloride (NaCl) in 1000 mL of 5% dextrose and 0.45% normal saline (D5 and 1/2 NS)
D5= dextrose 5% = 5 g dextrose per 100 mL NS 0.45% = 0.45 g NaCl per 100 mL Solve: 5 g : 100mL = x(g) : 1000mL Solve: Solve: 0.45 g : 100 mL = x(g) : 1000 mL Answer: 1000 mL D5 0.45% NS contains 50 g of dextrose and 4.5 g of NaCl.
Shortcut for Calculating IV Flow Rate for Large Volume
Determine Drop Factor Constant of the administration IV set: 15 gtt/mL = 4 20 gtt/mL = 3 10 gtt/mL = 6 60 gtt/mL = 1 Amount of solution (mL) Calculate x (mL/hr)= ----------------------------------- Time in hours mL/ hr Calculate gtt/min = ------------------------------ Drop factor constant
Shortcut for Calculating IV Flow Rate
Determine Drop Factor Constant of the administration IV set: 15 gtt/mL = 4 20 gtt/mL = 3 10 gtt/mL = 6 60 gtt/mL = 1 mL/ hr Calculate gtt/min = ------------------------------ Drop factor constant
D5RL
Dextrose 5% and lactated Ringer's
D5 1/4NS (0.225%)
Dextrose 5% in 0.225% sodium chloride
D5 1/2NS (0.45%)
Dextrose 5% in 0.45% sodium chloride
D5NS
Dextrose 5% in sodium chloride
D5W or 5%D/W
Dextrose 5% in water
Using Shortcut Method: Administer 0.9% NS at 75 mL/hr. The drop factor is 60 gtt/mL
Drop Factor Constant = 1 75mL/ hr Calculate gtt/min = ---------------------- = 75 gtt/min 1
Order: R/L 1500 mL in 12 hr. Drop factor: 15 gtt/mL
Drop Factor Constant = 4 1500 mL Calculate mL/hr = ------------- = 125 mL/hr 12 hr 125mL/ hr Calculate gtt/min = ---------------------- = 31.2 = 31 gtt/min 4
Using Shortcut Method: Administer D5W at 125 mL/hr. The drop factor is 15 gtt/mL
Drop Factor Constant = 4 125 mL/ hr Calculate gtt/min = ---------------------- = 31.2 = 31 gtt/min 4
Order: The following IV's for 24 hours. Drop factor: 15 gtt/mL 1000 mL D5W with 10 mEq potassium chloride (KCl) 500 mL dextrose 5% in normal saline (D5NS) with 1 ampule multivitamin 500 mL D5W
Drop factor: 15 gtt/mL Drop Factor Constant = 4 2000 mL (1000 + 500 + 500) Calculate mL/hr = ------------- = 83.3= 83 mL/hr 24hr 83 mL X 15 gtt/mL Calculate gtt/min = -------------------------- = 20.7 = 21gtt/min 60 min
IV Medications (IVPB): Calculate rate (gtt/min) Order : Keflin 2 g IVPB over 30 min. The Keflin is placed in 100 mL of fluid after it is dissolved. The drop factor is 15 gtt/mL.
Drop factor: 15 gtt/mL Time: 30 min Volume= 100 mL 100 (mL) X 15 (gtt/mL) gtt/min = -------------------------------- = 50 gtt/min 30 min
Points To Remember
Drop factor= gtt/mL
Order: 15 mEq of potassium chloride in 1000 mL of D5 and 1/2 NS to be administered at a rate of 4 mEq per hour.
How many mL of solution are needed to administer 4 mEq/hr? 15 mEq : 1000 mL = 4 mEq : x (mL) 15x = 1000 x 4 15x = 4000 x= 266.6 = 267 mL ** 267 mL of fluid needed to administer 4 mEq per hour. Calculate the rate in gtt/min at which to deliver 4 mEq/hr. (Drop factor: 10 gtt/mL) 267 (mL) X 10 (gtt/mL) gtt/min = -------------------------------- = 44.5= 45 gtt/min 60 min **45 gtt/min would deliver 4 mEq of potassium chloride per hour from this solution
Recalculating IV Rate
IV flow rates must be monitored by the nurse. When IV solutions are behind or ahead of schedule, the flow rate must be recalculated by using the following equation: Volume (mL) remaining -------------------------------- Time remaining
Points To Remember
Knowing the drop factor is the FIRST step in accurate administration
RL or RLS
Lactated Ringer's solution (electrolytes)
Points To Remember
Macrodrops are large and deliver 10, 15, or 20 gtt/mL
Points To Remember
Microdrops are small and deliver 60 gtt/mL
Determining hour: IV is regulated at 20 microgtt/min. How many hours will it take for 100 mL to infuse?
Note: If an IV is regulated at 20 microdrops, then the drop factor is a microdrop (60 gtt/mL). 100 mL X 60 gtt/mL 20 microgtt/min = ------------------------------ x time in minutes 20x = 100 x 60 20x = 6000 x= 300 min Change minutes to hours: 60 minutes= 1 hr 300 / 60 = 5 hours
1/2 NS
Sodium chloride 0.45%
NS
Sodium chloride 0.9%
Important to Remember
Solution strength expressed as a percentage means gram of drug per 100mL of fluid. (%= gram per 100mL)
Determining the Amount of Drug in a Specific Amount of Solution
Sometimes medications are added to IV solutions, and the prescriber orders a certain amount of the drug to be given in a certain time period. 1- Calculate the number of mL of solution needed to deliver a certain amount of the drug per hour 2- Determine rate of flow (gtt/min)
Points To Remember
The drop factor always appears on the package of the IV tubing.
Recalculating IV Rate
The recalculated flow rate should not vary from the original rate by more than 25%. Check with the prescriber regarding an IV increase >25%. To determine the percentage of increase and decrease, divide the amount of increase or decrease by the original rate.
IV Medications: IVPB
The volume of the piggyback container is usually 50 to 100 mL and should infuse over 20, 30, or 60 minutes, depending on the type and amount of medication added.
Points To Remember
To calculate IV flow rate in gtt/min, the nurse must have the volume of solution, the time factor, and the drop factor of the tubing.
Points To Remember
To determine flow rates for an electronic infusion device (pump or controller), determine mL/hr by using the following equation: Total mL ordered x mL/hr (rounded to the nearest whole number) = ----------------------- Total hr ordered
Calculating Total Infusion Time
Total number of mL to infuse ------------------------------------------- = Total infusion time mL/hr infusing at