1 Chapter 7, Medication Administration Part 3 Medication Mathematics 2 Metric System Three fundamental units Grams Meters Liters 3 Conversion Between Prefixes Kilo (k) Hecto (h) Deca (D) Deci (d) or 0.1 Centi (c) or 0.01 Milli (m) or 0.001 Micro (mcg or ug) or 0.000001 4 Metric Equivalents 1 gallon liters 1 quart liters 1 cup ml 1 tablespoon ml 1 teaspoon ml 5 Weights and Temperature 1kg pounds Kilogramspounds/2.2 is the Metric system of measuring temperature F ( C + 32) C ( F 32) 6 Medical Calculations 7 Desired Dose Specific of medication needed. Most doses expressed as weight: Grams.. Micrograms. May be standard or based on body. 8 Dosage and Volume on Hand The amount of drug in a solution. is the weight per volume. Example: 1
D50W is supplied as 25 grams in 50cc 25 grams is the on hand 50mL is the on hand Concentration is 25gm/50cc or 0.5gm/cc Concentrations are on ALL liquid medication labels 9 Calculating Medication Doses volume on hand X desired dose dosage on hand All weights and volume measurements must be with the same metric prefix 10 Calculating Medication Doses Example You are ordered to administer 3mg of Morphine. Morphine is supplied as 10mg in 1 cc. Desired dose?? mg Dosage on hand?? mg Volume on hand?? cc 11 Calculating Medication Doses volume on hand ( cc) X desired dose ( mg) dosage on hand ( mg) 1 X 3 10 cc 12 Weight Dependent Dosages Many medications are weight dependent You must first convert pounds to Then, multiply kg by indicated per kg. Example You are ordered to administer 1mg/kg of Lidocaine to a patient who weighs 110 pounds. Lidocaine is supplied as 100mg in 10cc. 13 Weight Dependant Dosage Example (1 of 2) 110/2.2 kg 50kg X 1mg 50mg Desired Dose?? Dosage on hand?? 2
Volume on hand?? 14 Weight Dependant Dosage Example (2 of 2) volume on hand ( cc) X desired dose ( mg) dosage on hand ( mg) 10 X 50 100 15 Calculating Infusion Rates Fluid Volume Over Time: drops/minute Volume to be administered x drip factor Time in minutes Drip Factor # of drops per Stated on package Some are adjustable Normally drop (gtt), drop, or drop per cc 16 Fluid Over Time Example (1 of 2) You are ordered to establish an IV of Normal Saline to administer 300 cc per hour. How many drops/minute for a 10 drop IV set? Volume to be administered?? Drip factor?? Time in minutes?? 17 Fluid Over Time Example (2 of 2) drops/minute Volume to be administered ( cc) x drip factor ( ) Time in minutes ( ) 300 x 10 60 3000 60 3
drops per minute 18 Calculating Infusion Rates Medicated Infusions: Drops/minute Volume on hand x drip factor x desired dose Dosage on hand 19 Calculating Infusion Rates Volume on Hand amount in IV bag Normally 250cc, 500cc, or 1 liter (1,000cc) Desired dose to be given Dosage on hand amount of dosage 20 Medicated Infusion Example (1 of 3) You are ordered to administer 2mg per minute of Lidocaine. Lidocaine is supplied as 1 gram in 250cc of D5W. What is the drops per minute? Desired dose?? Dosage on hand?? 1 gram ( mg) 21 Medicated Infusion Example (2 of 3) Volume on hand?? cc Drip factor?? gtt/ml 22 Medicated Infusion Example (3 of 3) Drops/minute Volume on hand ( cc) x drip factor(60) x desired dose (2mg) Dosage on hand ( mg) 250 x 60 x 2 1,000 30,000 1,000 drops per minute 23 Medicated Infusion Example 2 (1 of 3) You are ordered to administer a Dopamine drip at 10mcg/kg/minute to a 55-year-old male who weighs 176 pounds. Dopamine is supplied as 200mg in 250cc. Using a 60 drop set, how many drops/minute do you deliver? 4
VOH X DF X DD DOH 24 Medicated Infusion Example 2 (2 of 3) VOH? DF? DD? 176/2.280 80 X 10800 800/1,000.8 DOH? 25 Medicated Infusion Example 2 (3 of 3) VOH ( ) X DF ( ) X DD ( ) DOH ( ) 12,000 gtt/minute 26 Dosage and Infusion Rates in Pediatric Patients flow rates are critical in pediatric patients since they cannot tolerate over or under doses. Use only a drop set or a type infusion set 5