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CHAPTER 18 IV MEDICATION AND TITRATION CALCULATIONS 169 CHAPTER 18 IV Medication and Titration Calculations Objectives The learner will calculate: 1. flow rates to infuse ordered dosages. 2. dosages and flow rates based on kg body weight. 3. dosage and flow rate ranges for titrated medications. Suggested Review Questions 1. How is the dimensional analysis (DA) equation written when calculating IV flow rates if strength of medication is given and dose per hour or per minute is ordered? 2. What is the two-step process for using DA to calculate IV flow rates when medication dosages are ordered by body weight? 3. What is the one-step process for using DA to calculate IV flow rates when medication dosages are ordered by body weight? 4. What does it mean to titrate a medication dose? How are titrated medication doses to be calculated? Answers to Review Questions 1. The DA equation for calculating IV flow rates when strength of medication and dose per hour are given is mL/hr = strength of medication present (mL/mg) × rate in mg/hr = mL mg × mg hr When the dose is specified in amount of drug per minute, the conversion of 60 min = 1 hr needs to be added to the equation. When the dose per minute or hr is given as a measure different than the strength of medication provided, the conversion for the measure needs to also be included in the equation. Therefore, when mL/hr infusion rate is desired for a © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 170 SECTION 6 INTRAVENOUS CALCULATIONS medication dosage of mcg/min and the medication dosage provided is mg/volume of fluid, the equation is mL/hr = 2. mL (volume on hand) 1 mg (dose conversion) mcg desired 60 min × × × mg (of drug in vol) 1000 mcg 1min (time to deliver dose) 1 hr The two-step process for using DA to calculate mL/hr IV flow rates for medications ordered by body weight is to first calculate the dosage for the patient’s weight and then proceed with the DA equation. So the patient’s weight in kg is determined, then the ordered dose per kg. The dosage for the patient’s weight is entered third in the equation as noted above. Remind students to compute body weight in kg to the nearest tenth and to calculate IV flow rates of medications to the nearest tenth mL. 3. The one-step process for using DA to calculate mL/hr IV flow rates for medications ordered by body weight is to include the dose per patient’s weight conversion in the DA equation. This does result in a long equation and careful attention must be paid to the entry of ratios. The patient’s weight is converted to kg (if given in lb) before the patient’s weight is entered into the equation. The desired dose per kg weight is entered as the third ratio of the equation with the desired dose as numerator and kg/min as denominator. The patient’s weight in kg is entered as the numerator in the last ratio of the equation. The equation is: mL mL 1 mg mcg desired 60 min wt in kg = × × × × hr mg 1000 mcg 1 min 1 hr 1 4. To titrate a medication dose is to adjust the medication dose within a specified range to achieve the physiologic response desired. When a titrated dose of medication is ordered, a minimum dose and maximum dose are identified. Both of these doses are calculated. Treatment is initiated using the minimum dose; the dose is then increased as needed, but it never exceeds the maximum dose unless new medication orders are written. Minimum and maximum doses are calculated using DA following the equations previously learned. © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. CHAPTER 18 IV MEDICATION AND TITRATION CALCULATIONS 171 Name ____________________________________________ Date ____________________ Chapter 18: IV Medication and Titration Calculations Additional Practice Problems Calculate the dosages and IV flow rates as requested for the medications below. Round answers to nearest tenth. 1. Lidocaine hydrochloride 20 mcg/kg/min has been ordered for a patient with a cardiac dysrhythmia. The patient weighs 79.5 kg. The solution available is 1 g in 250 mL D5W. mcg/min dosage 2. _______________ mL/hr flow rate _________________ Dopamine hydrochloride has been ordered for a patient who weighs 73.6 kg to maintain blood pressure. The dosage range is 2 to 5 mcg/kg/min. The solution available is 400 mg 3. in 500 mL D5W. What is the dosage range for this patient? _________________ What is mL/hr flow rate to deliver 2 mcg/kg/min? _________________ Dobutamine has been ordered for a child who weighs 23.6 kg. The ordered dose is 5 mcg/kg/min. Solution available is 250 mg/50 mL of 0.9% NaCl. mcg/min dosage 4. ______________ mL/hr flow rate _________________ Nitroglycerin is ordered for a patient with chest pain. The ordered dose is 5 mcg/kg/min to keep the patient pain free. The patient weighs 61.4 kg. The IV solution available is nitroglycerin in normal saline at a concentration of 500 mcg/mL. mcg/min dosage 5. _______________ mL/hr flow rate _________________ A dosage of medication is ordered to infuse at 17 mg/hr. The IV solution is prepared at the concentration of 250 mg of medication in 500 mL of D5W. mL/hr flow rate 6. _______________ An IV infusion containing 2 g of medication in 1 L of normal saline is to infuse at 2 to 3 mg/min. What is the mL/hr flow range? ________________ © 2010 Cengage Learning. All Rights Reserved. Permission to reproduce granted for classroom use only. 172 7. SECTION 6 INTRAVENOUS CALCULATIONS A dosage of medication at a concentration of 2 g in 500 mL D5W is ordered to infuse at 96 mg/hr. mL/hr flow rate 8. ________________ The initial dose of a cardiac drug is ordered at 25 mg/hr. The solution was prepared at a concentration of 125 mg/100 mL of D5W. mL/hr flow rate 9. ________________ A medication at the dose of 2 mcg/min has been ordered. The solution was prepared at a concentration of 1 mg in 250 mL of D5W. mL/hr flow rate 10. ________________ A medication is to be titrated to 10 mcg/kg/min. The IV solution was prepared by adding 250 mg of the medication to 250 mL D5W. The patient weighs 60 kg. mL/hr flow rate 11. ________________ Epinephrine in D5W is to be run at 2 mcg/min to maintain BP and heart rate. The IV solution was prepared by adding 2 mg of epinephrine to 250 mL D5W. mL/hr flow rate 12. ________________ A medication is to be titrated to 150 mcg/kg/min. The IV solution was prepared by adding 2.5 g of medication to 250 mL of D5W. The patient weighs 91.8 kg. mL/hr flow rate 13. ________________ An initial dose of a cardiac drug is ordered at 25 mg/hr. The solution was prepared by adding 125 mg of the medication to 100 mL of D5W. mL/hr flow rate 14. ________________ A medication is ordered to infuse at 40 mcg/kg/min. The patient weights 60 kg. The IV solution was prepared at a concentration of 1 g of medication in 500 mL D5W. mL/hr flow rate ________________ © 2010 Cengage Learning. All Rights Reserved. Permission to reproduce granted for classroom use only. CHAPTER 18 IV MEDICATION AND TITRATION CALCULATIONS 15. 173 The physician ordered aminocarproic acid 30 mg/kg/hr for a child who is bleeding. The child weighs 27.3 kg. The IV solution has been prepared at a concentration of 5 g of aminocarproic acid in 250 mL of NS. mg/hr dose 16. _______________ mL/hr flow rate __________________ A medication dosage of 3 mcg/kg/min has been ordered for a patient who weighs 87.3 kg. The IV solution was prepared at a concentration of 50 mg in 250 mL D5W. mL/hr flow rate 17. _______________ Procainamide at the dose of 6 mg/min has been ordered for a patient experiencing a dysrhythmia. The medication was prepared at a concentration of 1 g procainamide in 250 mL of NS. mL/hr flow rate 18. _______________ A medication dosage of 2 mcg/min has been ordered. The medication has been prepared at a concentration of 1 mg/250 mL D5W. mL/hr flow rate 19. _______________ The physician has ordered amiodarone at a dose of 0.5 mg/min. The medication has been prepared at a concentration of 1g aminodarone to 500 mL of NS. mL/hr flow rate 20. _______________ Propofol at the dose of 5 mcg/kg/min has been ordered to maintain sedation for a patient receiving mechanical ventilation. The patient weighs 84 kg. The medication was prepared at a concentration of 500 mg in 250 mL of D5W. mL/hr flow rate ________________ © 2010 Cengage Learning. All Rights Reserved. Permission to reproduce granted for classroom use only. 174 SECTION 6 INTRAVENOUS CALCULATIONS Solutions to Additional Practice Problems Calculate the dosages and IV flow rates as requested for the medications below. Round answers to the nearest tenth. 1. mcg/min = 20 mcg/kg/min × 79.5 kg = 1590 mcg/min Convert 1 g to mg: 1 g = 1000 mg before setting up the DA equation 1 1 1 mg 79.5 kg 4770 mL 250 mL 60 min = × = × × × hr 200 1 hr 1000 mg 1000 mcg kg / min 4 20 mcg 50 = 23.85 mL/hr (rounded to the nearest tenth) = 23.9 mL/hr 2. Lower dosage range = 2 mcg/kg/min × 73.6 kg = 147.2 mcg/min Upper dosage range = 5 mcg/kg/min × 73.6 kg = 368 mcg/min. Dosage range is 147.2 to 368 mcg/min. 1 6 1 mg 147.2 mcg mL 500 mL 60 min 883.2 = × = × × hr 1 hr 80 1000 mcg 1 min 400 mg 40 2 = 11.04 mL/hr (rounded to the nearest tenth) = 11 mL/hr 3. mcg/min = 5 mcg/kg/min × 23.6 kg = 118 mcg/min 1 6 1 mg 118 mcg mL 50 mL 60 min 780 × × = × = hr 1 hr 500 250 mg 1000 mcg 1 min 25 20 = 1.41 mL/hr (rounded to the nearest tenth) = 1.4 mL/hr 4. mcg/min = 5 mcg/kg/min × 61.4 kg = 307 mcg/min 6 307 mcg mL 1 mL 60 min 1842 × = × = hr 1 hr 50 500 mcg 1 min 50 = 36.84 mL/hr (rounded to the nearest tenth) = 36.8 mL/hr 2 5. 17 mg mL 500 mL = 34 mL/hr = × 1 hr hr 250 mg 1 © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. CHAPTER 18 IV MEDICATION AND TITRATION CALCULATIONS 175 1 6. 2 mg mL 1000 mL 60 min 120 = × = = 60 mL/hr to × hr 1 hr 2 2000 mg 1 min 2 1 3 mg mL 1000 mL 60 min 180 × = × = = 90 mL/hr hr 1 hr 2 2000 mg 1 min 2 7. Convert 1 g to mg: 2 g = 2000 mg before setting up the DA equation 1 96 mg mL 500 mL 96 × = = = 24 mL/hr hr 1 hr 4 2000 mg 4 1 8. 25 mg mL 100 mL 100 × = = = 20 mL/hr hr 1 hr 5 125 mg 5 1 9. 1 mg 2 mcg mL 250 mL 60 min 120 × × = × = = 30 mL/hr hr 1 hr 4 1000 mcg 1 min 1 mg 4 1 1 10. 1 mg 10 mcg 60 kg 3600 mL 250 mL 60 min × × × = × = = 36 mL/hr 1 hr hr 100 250 mg 1000 mcg 1 kg / min 1 100 1 1 11. 1 mg 2 mcg mL 250 mL 60 min 60 × × = × = = 15 mL/hr hr 1 hr 4 1000 mcg 1 min 2 mg 1 12. 4 Convert 2.5 g to mg: 2.5 g = 2500 mg before setting up the DA equation 3 1 1 mg 91.8 kg 16,524 mL 250 mL 60 min × × × = × = 1 hr hr 200 2500 mg 1000 mcg 1 kg / min 10 150 mcg 20 = 82.62 mL/hr (rounded to the nearest tenth) = 82.6 mL/hr © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 176 SECTION 6 INTRAVENOUS CALCULATIONS 1 13. 25 mg mL 100 mL 100 × = = = 20 mL/hr hr 1 hr 5 125 mg 5 14. Convert 1 g to mg: 1 g = 1000 mg before setting up the DA equation 1 1 1 mg 60 kg 3600 mL 500 mL 60 min = × = = 72 mL/hr × × × hr 50 1 hr 1000 mcg 1 kg / min 1000 mg 2 15. 40 mcg 25 mg/hr = 30 mg/kg/hr x 27.3 kg = 819 mg/hr Convert 5 g to mg: 5 g = 5000 mg before setting up the DA equation 1 30 mg mL 250 mL 27.3 kg 819 × × = = hr 1 hr 20 5000 mg 20 = 40.95 mL/hr (rounded to the nearest tenth) = 41 mL/hr 5 16. 6 1 mg 3 mcg 87.3 kg 7857 mL 250 mL 60 min = × = × × × hr 100 1 hr 50 mg 1000 mcg 1 kg / min 1 100 = 78.57 mL/hr (rounded to the nearest tenth) = 78.6 mL/hr 1 17. 6 mg mL 250 mL 60 min 360 × = × = = 90 mL/hr hr 1 hr 4 1 min 1000 mg 4 1 18. 1 mg 2 mcg mL 250 mL 60 min 120 × × = × = = 30 mL/hr hr 1 hr 4 1000 mcg 1 min 1 mg 4 19. Convert 1g to mg: 1 g = 1000 mg before setting up the DA equation 1 0.5 mg mL 500 mL 60 min 30 × = × = = 15 mL/hr hr 1 hr 2 1 min 1000 mg 2 © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. CHAPTER 18 IV MEDICATION AND TITRATION CALCULATIONS 1 1 20. 177 1 mg 84 kg 5040 mL 250 mL 60 min × × × = × = = 12.6 mL/hr 1 hr hr 200 1000 mcg 1 kg / min 500 mg 2 5 mcg 200 © 2010 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.