Using Basic Math for Critical Care Intravenous Calculations

Transcription

1 Bridging the Gap Using Basic Math for Critical Care Intravenous Calculations

2 Disciplines Clinical Nursing Calculations1 and Basic Math. Purpose of Project To help nursing students to master critical care IV calculations. Brief Summary Development of a Web companion to NUR 213 Pharmacology III with three learning modules 1. Calculating dose per hour or minute. 2. Calculating rate of infusion in ml/h 3. Calculating dose and infusion rate based on body weight. Three methods are presented for each module: Ratio and Proportion, Formula, and Dimensional Analysis Materials Needed Access to BlackBoard Calculator Target Audience Second year associate degree nursing students. Time Management Pre-Assessment: September 10 th (15 minutes) Three Blackboard Modules self-paced: approximated total time 3 hours Post-Assessment: December 13 th (15 minutes) Prior Knowledge Needed Basic Math and Basic Nursing Dosage Calculations

3 Activities 1. Blackboard Modules Module 1: Calculating Dose of Medication /hour or minute You are caring for a patient who is receiving IV heparin. 25,000 units of heparin is dissolved in 1,000 ml of D5W. The IV solution is infusing at a rate of 30 ml /h on a volumetric pump. What is the hourly dose of heparin your patient is receiving? 1000 ml 5 % Dextrose Solution Let s think about what you are being asked. You know that your patient is receiving 30 ml of the solution per hour. You need to know how much heparin is in 30 ml of the solution. Method 1 Ratio and Proportion Build a proportion and solve it 25,000 units 1,000 ml = x 30mL Cross Multiply: 1,000 ml (x units) = 25,000 units (30 ml) Solve for x by dividing both sides of the equation by 1,000 ml x = 25,000 units (30 ml) 1,000 units 25,000 units Heparin Sodium = 750 units/h

4 Method 2 - Find out how many units of heparin are in a ml and multiply by the hourly infusion rate. 25,000 units 1,000 ml = 25 units/ml Patient is receiving 30 ml of this solution per hour. 25 units ml 30 ml = 750 units/h Method 3 Dimensional Analysis a) What is the end point? In this case we need to get to units of heparin/h. b) Where is the beginning or given quantity? In this case, start with the amount of medication per volume of IV fluid. In other words, what is in the IV bag? c) What is the unit path? How will we get from the starting point to the end point? We set up the path using conversion factors that cancel out the labels we do not want. In this problem the path is short. We only need one conversion factor. 25,000 units 1,000 ml 30 ml 1 h = 750 units/h

5 Module 2: Calculating the infusion rate of the solution (ml/h) The medication order for your patient is as follows: Heparin 1,200 units/h IV. You will be using a solution of 20,000 units of heparin in 500 ml of D5W. What pump setting will you use? 500 ml 5 % Dextrose Solution Let s think about the question. You know that your patient has to receive 1,200 units of heparin each hour. The pump only understands ml/h. You need to find out how many ml of the solution will contain 1,200 units. Method 1 - Ratio and Proportion Build a proportion and solve it 20,000 units 500 ml = 1,200 units x ml Cross Multiply: 20,000 units (x ml) = 1,200 units (500 ml) Solve for x by dividing each side of the equation by 20,000 units x = 1,200 units (500 ml) 20,000 units = 30 ml So, 30 ml of the solution contains 1,200 units. You will set the pump at 30 ml/h.

6 Method 2 Use D/H Q formula D = H = Q = 1,200 units 20,000 units 500 ml 1,200 units 500 ml = 30 ml/h 20,000 units You will set the pump at 30 ml/h. Method 3 Dimensional Analysis a) What is the end point? In this case we need to get ml/h b) Where is the beginning? In other words, what is the given quantity? In this case we start with the amount of medication to be administer in units/h: 1200 units/h c) What is the unit path? Use the dosage on hand: 500mL/20,000units. We know we want to end up with ml on top, so we will put the volume of IV fluid on top and the units of Heparin on the bottom units h 500 ml 600,000 ml = = 30 ml/h 20,000 units 20,000 h You will set the pump at 30 ml/h

7 Module 3: Calculating Dose and Infusion Rate based on Body Weight You are caring for a patient who is receiving dopamine IV. The medication order is: dopamine 2 mcg/kg/min. The available IV solution is dopamine 400 mg in 250 ml D5W. The patient weighs 110 lb. What pump setting will you use? (Round answer to nearest tenth of an ml) 250 ml 5 % Dextrose Solution Dopamine 400 mg Method 1 Using Ratio and proportion. Before we get to setting up the ratio and proportions, we will need to do several conversions. a) Convert patient s weight to kg. 110 lb/ 2.2 = 50 kg b) Determine number of mcg/min patient must receive. 50 kg x 2 mcg/kg = 100 mcg per min c) Convert mcg/min to ml/h. First, convert mcg/min to mcg/h: 100 mcg/min x 60 min/h = 6,000 mcg/h Second, convert mcg/h to mg/h: 6,000mcg 1 h 1 mg 1,000 mcg = 6 mg/h d) Determine how many ml contains 6 mg. Remember, the IV solution is 250 ml of D5W containing 400 mg of dopamine.

8 400 mg 250 ml = 6 mg x Cross multiply: 400 mg ( x ) = 250 ml ( 6 mg) Solve for x by dividing both sides by 400 mg: 250 ml (6 mg) x = = 3.75 ml = 3.8 ml 400 mg So, 3.8 ml contains contains 6 mg of dopamine. will be 3.8 ml/h Therefore, the pump setting Method 2 Dimensional Analysis d) What is our end point? In this case we want to get to ml/h. It will be difficult to set the problem up that way, so we will solve the problem in 2 steps. First we will get to ml in one minute e) Where is the beginning or given quantity? In this case we start with the amount of medication to be administer: 2 mcg/kg in one minute f) Set up the unit path of conversion factors to get you to the end point. This time we know we want to end up with ml on top. So, we will put the volume of IV fluid on top and the mg of medication on the bottom.use the dosage on hand 250 ml/400 mg. 2 mcg kg 1 kg 250 ml 2.2 lb 400 mg 1 mg 110 lb = ml in 1 min mcg Then, we will use a second conversion factor to get ml/h: ml 1 min 60 min 1 h = 3.75 ml h = 3.8 ml/h Therefore, the pump setting will be 3.8 ml/h

9 2. Blackboard Quizzes Module 1 Quiz Points: 1) 1. The patient is receiving IV Lidocaine 1 g in 500 ml D5W. It is infusing at a rate of 30 ml/h. The 60 patient is receiving Fill in the Blank mg/h of Lidocaine. 2. Heparin 20,000 units in 500 ml D5W is infusing IV at 40 ml/h. How many units of Heparin is the 1,600 patient receiving per hour? Fill in the Blank units/h 3. The patient is receiving an IV of 50 units of insulin in 100 ml Normal Saline. It is infusing at a rate of 10 ml/h. How many units of insulin is the patient receivng per hour? Fill in the Blank 5 units per hour. 4. Aminophylline 1,000 mg in 500 ml D5W is infusing IV at a rate of 10 ml/h. Calculate the patient's hourly dose of aminophylline in mg. 20 Fill in the Blank mg/h 5. The patient is receiving an IV of 100 mg Nitroglycerin in 250 ml D5W at a rate of 9 ml/h. How many mcg/min of Nitroglycerin is the patient receiving? Fill in the Blank 60 mcg/min

10 Module 2 Quiz 1. The IV medication order is for 125 mg diltiazem in 500 ml D5W to infuse at 5 mg/h. The nurse will set the IV pump rate at Fill in the Blank 20 ml/h. 2. The doctor has ordered Pronestyl 2 g in 500 ml D5W to infuse at a rate of 6 mg per min. The nurse will set the IV pump rate at Fill in the Blank 90 ml/h 3. The medication order is for 100 ml D5W with 125 mg Cadizem. The patient is to receive 10 mg/h. The nurse will set the IV pump at a rate of Fill in the Blank 8 ml/h. 4. The doctor has ordered 10,000 units of heparin per 500 ml D5W to infuse at a rate of 1,000 units per hour. The nurse will set the IV pump at Fill in the Blank 50 ml/h. 5. The IV medication order is for dobutamine 250 mg in 250 ml D5W to infuse at 100 mcg per min. The nurse will set the IV pump rate at Fill in the Blank 6 ml/h.

11 Module 3 Quiz. 1. The patient weighs 165 lb. The medication order is for 400 mg dopamine in 500 ml D5W at 9 mcg/kg/min. At what rate will the nurse set the IV pump? Fill in the Blank 51 ml/h Round answer to nearest whole ml. 2. The patient weighs 154 lb. The medication order is for 50 mg nitroprusside in 250 ml NS to infuse IV at 2 mcg/kg/min. At what rate willl the nurse set the pump? Fill in the Blank 42 ml/h 3. Dopamine 400 mg in 500 ml D5W has been ordered to run at 10 mcg/kg/min for a patient who 60 weighs 80 kg. What IV pump rate will the nurse use? Fill in the Blank ml/h 4. Medication order is for Inotropin 800 mg in 500 ml D5W to infuse at 4 mcg/kg/min. The patient weighs 176 lb. At what rate will the nurse set the IV pump? Fill in the Blank 12 ml/h 5. The patient is receiving an IV of dopamine 400 mg in 500 ml D5W to infuse at 20 mcg/kg/min. The patient weighs 72 kg. At what rate will the nurse set the IV pump? Fill in the Blank 108 ml/h

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13 3. Pre- and Post-Assessments Course: Date: pre or post assessment? Pre-assessment or post-assessment (please circle the appropriate one) MATHEMATICS ACROSS THE COMMUNITY COLLEGE SURVEY This course is part of a project funded by the National Science Foundation to measure the impact of different instructional approaches. Please answer honestly and thoughtfully and remember, there are no right or wrong answers. Your responses are very important to the research and will be treated with great respect and confidentiality. Please fill in the last 5 digits of your Student Identification Number (This information enables us to match surveys from the beginning and end of the course. it does not enable us to identify you.) Age: Gender: M F THANK YOU.

14 Please circle the number that best describes your position on the scale where 1= "strongly AGREE" and 5 = "strongly DISAGREE." 1. I am good at math. Strongly Strongly Agree... Disagree 2. Mathematics is facts, rules, and formulas to be memorized. 3. Doing math in another subject makes the math easier to learn. 4. Doing math in another subject makes the other subject easier to learn. 5. I don t need a good understanding of math to achieve my career goals. 6. I enjoy doing mathematics. 7. Estimating is a part of doing mathematics. 8. I rarely use math outside of school 9. I am comfortable talking about mathematics. 10. Math problems can be done correctly in only one way. 11. Lots of things I do every day involve math. 12. I feel comfortable asking questions in my classes when I don t understand things about math. 13. I am going to study more math. 14. I am afraid of math problems. 15. In mathematics I can be creative and discover things for myself. 16. After I've forgotten all the formulas, I'll still be able to use ideas I've learned.

15 Please solve the following intravenous calculation problems. 17. The patient is receiving Heparin 20,000 units in 500 ml D5W. Infuse at 12 ml/h. Calculate the hourly dose of heparin the patient is receiving. units/h 18. The medication order if for Heparin 20,000 units in 500 ml D5W to infuse at 700 units per hour. What pump rate will the nurse use? Express your answer to the tenth of a ml. ml/h 19. The patient weighs 132 lb. Medication order is for dopamine 800 mg in 250 ml D5W to infuse at 10 mcg/kg/min. What pump setting will the nurse use? Round answer to nearest tenth of a ml. ml/h How difficult did you find solving these problems to be? Please explain your answer. Thank you

16 Answer key - Pre and Post Assessment Answers 17. The patient is receiving Heparin 20,000 units in 500 ml D5W. Infuse at 12 ml/h. Calculate the hourly dose of heparin the patient is receiving. 20,000 units = X 500 ml 12 ml X = 20,000 units x 12 ml = 480 units per hour 500 ml 18. The medication order if for Heparin 20,000 units in 500 ml D5W to infuse at 700 units per hour What pump rate will the nurse use? Express your answer to the tenth of a ml. 20,000 units = 700 units 500 ml X X = 500 ml x 700 units X = 17.5 ml/h 20,000 units 19. The patient weighs 132 lb. Medication order is for dopamine 800 mg in 250 ml D5W to infuse at 10 mcg/kg/min. What pump setting will the nurse use? Round answer to nearest tenth of a ml. 132 lb / 2.2 = 60 kg 60 kg x 10 mcg/kg/min = 600 mcg/min 600 mcg/min x 60 min/h = 36,000 mcg/h 36 mg/h 36,000 mcg x 1 mg/ 1000 mcg = 800 mg = 36 mg 250 ml X X = 250 ml x 36 mg 800 mg X = = 11.3 ml/h

17 4. Additional File: BlackBoard Read Me First document Welcome to the NUR 213 Critical Care Calculations Module This module was developed as a Math across the Curriculum Project, funded by the National Science Foundation. Designers: Liliana Brand, Math Department Sheila Kane, Nursing Department Purpose: To help you master Critical Care IV Calculations. Grading: The learning activities and assessments are not included in your course grade. However, these calculations will be on course exams. Objectives: 1. Calculate the dose of medication a client is receiving IV, when given the concentration of the solution and the rate of infusion. 2. Calculate the rate of infusion, when given the concentration of the solution and the dose of medication to be administered. 3. Calculate dose and determine infusion rate for medication based on mcg/kg/min. Methods: Learning activities will use 3 different approaches: Dimensional Analysis Formula Ratio and proportion