62 DOSAGE CALCULATIONS

DOSAGE CALCULATIONS Fundamentals of nursing pg 736-738 Medical Dosage Calculations Olsen, et al Objectives  Goal   Nursing students will demonstrate dosage calculations competency by passing a required dosage calculation test with a 90% or better Objectives   Students will understand how to correctly convert numbers between and within apothecaries, household, and metric measurement systems Students will demonstrate ability to accurately calculate drug dosages Dosage Calculation Test      Must pass with a 90% or higher Three attempts allowed to pass You WILL NOT proceed in the program if you not pass the dosage calculation exam MUST complete remediation exercises prior to second or third attempt May use testing center issued calculator for test (basic function calculator) Testing in the Testing Center    Must have CSI ID card or can’t get in You must be checked in hour prior to testing center closing to receive test Identify test as following:    Class – NURP 106 (Fundamentals) Instructor: Paula Hart Test: Dosage Calculation Exam # (1, or 3)   Question- Why we care about getting 100% on our dosage calculations test? Answer- Because a human being could die from a wrongly placed decimal point or an accidental extra zero placed during a dosage calculation… It’s that important “3 babies died from the wrong dose of heparin given Dosage calculation errors were made.” Indianapolis Star/ Sept 19, 2006 What you need to be successful?     Review the content in this power point, your text book, text book site, and Kaplan site Ask for help if you need it from your instructors, math lab, internet sites Use ALL available resources PRACTICE, PRACTICE, PRACTICE Ready to begin? Math Review – Roman Numerals     Read from left to right A smaller numeral to the right of a larger numeral is added to the larger numeral A smaller numeral to the left of a larger numeral is subtracted from the larger numeral Easily translated to Arabic numbers Roman Numeral Practice        XXX = _ XIV = iii = XXV = _ XIX = VI = _ XXIV = _ Practice Problem #5  The order is to start a continuous tube feeding of 2/3 strength Jevity at 50ml/hr How much water will you add to the entire can to get the desired strength if each can contains 300ml? 300ml = x 300ml x 3= 2x 900ml=x 450ml=x 450ml-300ml=150 Reconstitution    Some medications are unstable when stored in solution or liquid form, therefore they are supplied as a powder Before they can be administered they must be dissolved or “reconstituted” by mixing with a diluent (liquid) The volume of diluent used to dissolve the powder determines its unit concentration or the dose of drug contained in 1ml (mg/ml) Reconstitution cont    Vials usually will have reconstituting directions printed on them so you must determine the type and amount of diluent to be added in order to reconstitute the drug correctly The resulting solution strength or concentration (mg/ml) will be found in the instructions on the vial The mg/ml is now the available dose of the drug ordered Reconstitution ex pges 237-244 Dosages based on body weight      Sometimes dosages are ordered by body weight of the pt., especially when giving pediatric doses Remember all medication math is done in the metric system, so weight for dosages must be converted and calculated in kg Remember 1lb=16oz, 1kg=2.2lb When converting from lbs to kg, divide by 2.2 When converting ounces to lbs divide by 16 Dosages based on body weight    Ex A baby weighs 10lb 12oz How many lbs is this? First divide 12oz by 16= 0.75lb So this baby weighs 10.75 lbs Now how many kg does this baby weigh? 10.75/2.2=4.88kg (leave at 4.88 for calculations) Now we must multiply the ordered mg/kg dose by the weight of the pt in kg to get the desired dose for that pt Then your dosage calculations Ex Ordered drug is 2mg/kg, available is 10mg/ml, the baby weighs 10lb 12oz, how much will you give?    Wt=4.88 kg 2mg/kg=9.8mg You will give 0.98ml or 1ml Practice problem  You have an order for cefaclor (Ceclor) 20 mg/kg/day in three divided doses The child weighs 20 lbs How much will you give in each dose?    Wt=9.09 Daily dose=181.8 Each dose=60.6 Calculating IV flow rates      IV flow rate is the speed at which the IV fluid infuses in the body Usually measured in drops per minute (gtt/min) The number of gtts required to deliver 1mL of fluid varies with the type of administration set used The administration set is made of plastic tubing, a drip chamber, and a “spike,” which is inserted into the bag/bottle of fluid/medication There are types of sets: Macrodrip=10,15,or 20 gtt/mL or Microdrip=60gtt/ml Calculating Flow rates for IVs   IV flow rate formula: Volume of infusion in mL x gtt factor = Flow rate time of infusion (usually in min) (usually in gtt/min) Ex: Administer D5 1/2NS at 30mL/hr using a microdrip 30mL x 60gtt/mL =30gtt/min 60 Administer 3,000mL D5 1/2NS in 24 hrs with a drop factor of 15gtt/mL 3000mL x 15gtt/mL = 31.25gtt/min 1440 Drugs Infusing in Less than hour: If a drug is ordered to be infused in hour or less what you do? Example: Mandol Gm in 50 mL NS Infuse in 30 minutes Adm Set: 15gtt/cc 50 mL x 15gtt/mL = 25gtt/min  30 Example:   You have an order for Aldomet 250 mg IVPB in 100 mL D5W to be infused over 45 minutes The administration set is labeled 10 gtt/mL What is the drop rate? 100 mL x 10gtt/mL = 22.22 or 22gtt/min 45 minutes Practice Problems  The nurse hangs Liter D5W to infuse over hours The administration set is labeled 60 gtt/mL What is the gtt/min? 1000 mL x 60gtt/ml =125gtt/min 480 Dosage Calculations  The doctor orders 50 mL of Normal Saline (NS) to infuse over 30 minutes Your tubing is labeled 15 gtt/mL 50mL x 15gtt/mL = 25gtt/min 30 minutes Do you now feel better about your knowledge of dosage calculations? Well, you should Looking to the future   This semester we covered the basic knowledge of dosage calculations Each semester the math test will add more advanced problem solving along with the basic concepts learned here So… Again ask for help if you need it and PRACTICE, PRACTICE, PRACTICE ...Objectives  Goal   Nursing students will demonstrate dosage calculations competency by passing a required dosage calculation test with a 90% or better Objectives   Students... calculate drug dosages Dosage Calculation Test      Must pass with a 90% or higher Three attempts allowed to pass You WILL NOT proceed in the program if you not pass the dosage calculation... 106 (Fundamentals) Instructor: Paula Hart Test: Dosage Calculation Exam # (1, or 3)   Question- Why we care about getting 100% on our dosage calculations test? Answer- Because a human being