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Grown Up... © A Newsletter For Those Who Care For ADOLESCENTS, ADULTS, and AGING ADULTS IV THERAPY… CALCULATING FLOW RATES Volume 17, Issue 4 April 2012 Editor-in-Chief: Mary Myers Dunlap, MAEd, RN BEHAVIORAL OBJECTIVES AFTER READING THIS NEWSLETTER THE LEARNER WILL BE ABLE TO: 1. Calculate IV infusion flow rates. 2. Describe fluid compartments within the human body. Maintaining a balance of fluid volumes and electrolyte compositions in the fluid compartments is essential to health. Fluid and electrolyte balance are closely interrelated. For example, when bodily fluid volume increases, as is often the case in congestive heart failure, serum sodium levels may decrease, causing hyponatremia. Major disturbances in fluid and electrolyte balance can rapidly alter cardiovascular, neurologic, and neuromuscular functions. Administration of IV fluids is the primary method of correcting fluid and electrolyte imbalances. Intravenous fluid must be given as ordered by the physician, the prescribed IV solution at a specific rate, neither too fast, nor too slow. Thanks to infusion pump technology, it may have been a while since we have actually counted drops. Is it really necessary to know how to calculate and count drops of an IV infusion? Yes! What happens in a situation when the pump fails and/or in an emergency situation when the IV tubing has to be removed from the pump? What if you are in a practice setting where infusion pumps are not available or there are not enough available? What if there is an emergency and the IV pump battery fails? Infusion pumps can fail, as can all electronic equipment. All nurses need to know how to calculate IV drip infusions. Hanging a bag of IV fluid is considered administration of a medication. Healthcare professionals must follow the “rights” of medication administration – the right patient is receiving the IV, the right drug (IV solution and/or additive) is being infused, the right dose (the infusion time), the right route (peripherally, centrally), and at the right time (500 ml NS in 8 hours), as well as the right documentation and the right reason. Be knowledgeable of the rate at which the IV is infusing. When a burette or small-volume IV solution bag is to be infused, without the use of an electronic device, the flow rate in gtts/min will need to be calculated. When an IV infusion pump is used, calculating the ml/hr is often required. Healthcare professionals must know the drops per minute to be infused, regardless of the device used. This is good practice, and what the prudent nurse would do, which is essential if a problem occurs and legal action is taken. This newsletter will review calculation of IV flow rates. As an introduction to types of IV solutions, which will be discussed in an upcoming newsletter, fluid compartments will also be discussed. CALCULATING INFUSION RATES The size of IV drops is regulated by the type of IV set being used, which is calibrated in number of gtt/ml. Unfortunately, not all sets (and their drop size) are the same. Each hospital uses at least two sizes of infusion sets, the standard, or macrodrip set, calibrated at 10, 15, or 20 gtt/ml, which is used for routine adult IV administrations; and a mini, or microdrip set, calibrated at 60 gtt/ml, which is used when more exact measurements are needed, for example, to infuse medications, or in critical care and pediatric infusions. The gtt/m calibration of each IV set is clearly printed on each tubing package. The first step in calculating flow rate is to identify the drop factor, the gtt/ml calibration of the set to be used for infusion. The order for the patient’s IV should include the type of IV solution prescribed, as well as the infusion time. For example, to hydrate a patient, the order is written as “LR 1 liter over 8 hours.” Therefore, 1 liter over 8 hours is the infusion time. Remember that “keep vein open” (KVO) or “wide open” are not appropriate orders because they do not specify a rate of flow. The specific rate may be measured as ml/hour or drops/min. To control or adjust the flow rate only drops per minute are used. To calculate the flow rate, one formula is as follows: Volume (total) x Drop factor (gtts/ml) = Flow rate (gtts/min) Time (in minutes) 1500 ml IV D5W is ordered over 12 hours using regular tubing (15 gtts/ml). How many drops per minute are needed to be delivered? Using the formula above: Example 1500 (total volume) x 15 gtts/ml = Flow rate (gtts/min) 720 (12 x60) 1500 x 15 = 22500 = 31.25 (31) gtts/min 720 Copyright © 2012 Growing Up With Us, Inc. All rights reserved. Page 1 of 4 This formula is useful when small-volume flow rates are used. An IV medication of 100 ml is to be infused Example in 40 min using a set calibrated at 15 gtt/ml. What is the flow rate? 1 liter of D5NS is to be infused at 30 ml per hour. The IV set delivers 60 gtts/ml. What is the correct rate of flow? Example 30 (ml/hr) x 60 gtts/ml = 30 gtts/min 60 Calculate the gtts/min to be infused: 100 (total volume) x 15 gtts/ml = Flow rate (gtts/min) 40 100 x 15 = 1500 = 37.5 (38) gtts/min 40 The answer can also be obtained by using ratios and proportions: 100 mL:40 min = X mL:1 min or 100 ml = X ml = 38 gtts/min 40 min 1 min Let’s try a another calculation using tubing that delivers 10 gtt/ml. The order reads: “Over the next 4 hours, infuse 500 ml of D5W. Add 20 MEq of KCL to solution.” The set is calibrated to deliver 20 gtt/ml. In drops per minute, what is the flow rate? Example Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min) 60 500 ml ÷ 12 (ml/hr) x 20 gtts/ml = Flow rate (gtts/min) 60 Let’s try a calculation using tubing that delivers 10 gtt/ml. The order reads: “Over the next 4 hours, Example infuse 500 ml of D5W. Add 20 MEq of KCL to solution. In drops per minute, what is the flow rate? Note: In this example, the KCL adds minimal volume and doesn’t need to be considered in your calculation of the flow rate. Volume (total) x Drop factor (gtts/ml) = Flow rate (gtts/min) Time (in minutes) 500 ml (volume) x 10 (gtts/ml) = Flow rate (gtts/min) 60 x 4 = 240 (minutes) 5000 = 20.8 (21) gtts/min 240 When an IV is ordered to infuse in more than 1 hour, this formula can still be used. However, to keep the numbers you are working with as small as possible, it is best to add a preliminary step and determine the ml/hr the ordered volume will represent. 60 will be the denominator, since there are 60 minutes in an hour. Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min) 60 1500 ml IV D5W is ordered over 12 hours using regular tubing. How many drops per minute are needed to be delivered? Example 1500 ml ÷ 12 (ml/hr) x 15 gtts/ml = Flow rate (gtts/min) 60 125 x 15 = 125 = 31.25 (31) gtts/min 60 Let’s try a calculation using a mini-dropper (60 gtt/ml) with this formula: Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min) 60 42 x 20 = 840 = 14 gtts/min 60 Regulating IV fluid is an ongoing process from the time that an IV infusion is started until it is completed. Hourly checks of an IV should include assessing and documenting the IV flow rate, the IV site, the patient’s response to the IV, how much fluid has infused, and how much fluid remains to be infused. FLUID COMPARTMENTS AND IV FLUIDS BASICS Fluids within the body are contained in two basic compartments - intracellular and extracellular. Intracellular fluid (ICF) consists of fluid contained within all body cells and is the larger of the two compartments. The extracellular fluid (ECF) compartment contains all the fluids outside the cells. The ECF is further divided into three areas - intravascular fluid (fluid within the blood vessels), interstitial fluid (that found in tissue spaces), and transcellular fluid (fluids contained in body spaces), such as cerebrospinal fluid, the pleural cavity, and joint spaces (synovial fluid). Intravenous solutions are comprised of fluids (the solvent) and particles (the solute) dissolved in the fluid. Because the walls that separate fluid compartments are porous, water moves freely between them. The tiny pores that line the walls of the cells and capillaries also let small solutes pass through easily. Changes in the level of solute concentration, as occurs in various types of IV solutions, influence the movement of fluid and electrolytes between the fluid compartments. An upcoming newsletter will discuss types of IV solutions with related nursing implications, as well as assessment of fluid overload and fluid deficit. Growing Up With Us, Inc. PO Box 481810 • Charlotte, NC • 28269 GUWU Testing Center www.growingupwithus.com/quiztaker/ Phone: (919) 489-1238 Fax: (919) 321-0789 Editor-in-Chief: Mary M. Dunlap MAEd, RN E-mail: [email protected] Website: www.growingupwithus.com Copyright © 2012 Growing Up With Us, Inc. All rights reserved. Page 2 of 4 Name:_____________________________________________________ Date:___________________________________ Employee ID#:____________________________________________ Unit:____________________________________ POPULATION/AGE-SPECIFIC EDUCATION POST TEST GROWN UP... Caring For Adolescents, Adults, and Aging Adults April 2012 Competency: Demonstrates Age-Specific Competency by correctly answering 9 out of 10 questions related to IV Therapy… Calculating Flow Rates. IV THERAPY… CALCULATING FLOW RATES 1. Which fluid compartment contains cerebrospinal fluid? a. b. c. d. intracellular interstitial transcellular intravascular 2. Changes in the level of solute concentration, as occurs in various types of IV solutions, influence the movement of fluid and electrolytes between the fluid compartments. a. True b. False 3. Identify the calibration in gtt/mL on this IV tubing package. a. b. c. d. more information is needed. 60 70 1883 4. An IV of 150 mL is to infuse in 1 hr using a set calibrated at 60 gtt/mL. Calculate the gtt/min flow rate. a. b. c. d. 15 25 38 150 5. An IV of 1000 mL is ordered to infuse in 5 hrs using a set calibrated at 10 gtt/mL. How many gtts / min should infuse? a. b. c. d. 8 33 83 200 Copyright © 2012 Growing Up With Us, Inc. All rights reserved. Page 3 of 4 Name:_____________________________________________________ Date:___________________________________ POPULATION/AGE-SPECIFIC EDUCATION POST TEST Unit:____________________________________ Employee ID#:____________________________________________ GROWN UP... Caring For Adolescents, Adults, and Aging Adults IV THERAPY… CALCULATING FLOW RATES 6. Over the next 4 hours, 500 ml of D5W with 20 MEq KCL is to be infused using tubing that delivers 15 gtts/ml. In drops per minute, what is the flow rate? a. b. c. d. 20 31 38 125 7. An IV medication of 60 ml is ordered to infuse in 30 min. The set calibration is 20 gtt/mL. Calculate the gtts/min flow rate. a. b. c. d. 3 20 30 40 8. A medication of 75 mL is to be administered in 50 min using a set calibrated at 10 gtt/mL. How many gtts /min will infuse? a. b. c. d. 13 15 30 38 9. An IV order written as “KVO” as well as, “wide open”, doesn’t specify the flow rate and should, therefore, not be carried out until there is clarification of the specific flow rate from the ordering physician. a. True b. False 10. The prudent healthcare professional does not need to calculate the flow rate, in gtts/min, the patient is receiving. a. True b. False Copyright © 2012 Growing Up With Us, Inc. All rights reserved. Page 4 of 4