FNP LAB

• Metric system


  A decimal system that is the most logically organized, where you convert and compute metric units using simple multiplication and division, and each basic unit of measurement is organized into units of 10
• Converting metric units


  1. Multiplying or dividing by 10 forms secondary units

  2. In multiplication the decimal point moves to the right

  3. In division the decimal moves to the left
• Basic units of measurement in metric system

  • Meter (length)
  • Liter (Volume)
  • Gram (Weight)
• For medication calculations, use only the volumes and weights unit
• Metric system units


  • Gram = g or GM
  • Liter = l or L
  • Milligram = mg
  • Milliliter = mL
• Metric prefixes


  • Deci-(1/10 or 0.1)
  • Centi- (1/100 or 0.01)
  • Milli- (1/1000 or 0.001)
• Many actual and potential medication errors happen with the use of fractions and decimal points
• Standard to prevent decimal point errors


  A leading zero is always placed in front of a decimal (e.g., use 0.25, not .25)
• Solution


  A given mass of solid substance dissolved in a known volume of fluid or a given volume of liquid dissolved in a known volume of another fluid
• Concentration of a solution


  Units of mass per units of volume (e.g., g/L, mg/mL)
• Percentage solution


  10% solution is 10 g of solid dissolved in 100 mL of solution
• Proportion


  A solution containing 1 g of solid in 1000 mL of liquid or 1 mL of liquid mixed with 1000 mL of another liquid
• Converting measurements within one system

  1. Divide or multiply in the metric system

  2. To change milligrams to grams, divide by 1000, moving the decimal 3 points to the left

  3. To convert liters to milliliters, multiply by 1000 or move the decimal 3 points to the right
• To convert from one measurement system to another, always use equivalent measurements
• Dosage calculation methods


  • Ratio and Proportion Method
  • Formula Method
  • Dimensional analysis
• Ratio


  Indicates the relationship between two numbers separated by a colon (:)
• Proportion


  An equation that has two ratios of equal value
• Solving a calculation using the ratio and proportion method

  1. Estimate the answer

  2. Set up the proportion, labeling all the terms

  3. Put the terms of the ratio in the same sequence

  4. Cross multiply the means and the extremes and divide both sides by the number before the x to obtain the dosage

  5. Always label the answer
• Formula Method


  1. Estimate the answer

  2. Set up the formula

  3. Calculate the answer

  4. Compare the estimate with the answer
• Formula method terms


  • Dose ordered
  • Dose on hand
  • Amount on hand
• Dimensional analysis


  The factor-label or the unit-factor method
• Steps in dimensional analysis

  1. Identify the unit of measure to administer

  2. Estimate the answer

  3. Place the name or abbreviation for x on the left

  4. Place available information in a fraction format on the right

  5. Add other factors into the problem

  6. Cancel out like units on the right

  7. Reduce to lowest terms and solve for x

  8. Compare estimate with answer
• Children are at a much higher risk for experiencing a medication error than adults, and medication errors in children have a much greater chance of causing serious and even fatal consequences
• Guidelines to prevent medication errors in children

  • Use only the metric system
  • Never administer medications using household spoons
  • Round all dosing instructions to the nearest 0.1, 0.5, or 1 mL
  • Provide education using hands-on demonstration and return demonstration
  • Consider using picture-based education if low health literacy is a possibility
• Guidelines for calculating pediatric doses

  • Weigh the patient in kilograms before administering medications
  • Pediatric doses are usually a lot smaller than adult doses
  • IM doses are very small and usually do not exceed 1 mL in small children or 0.5 mL in infants
  • Subcutaneous dosages are also very small and do not usually exceed 0.5 mL
  • Most medications are rounded to the nearest thousandth
  • Measure dosages less than 1 mL in syringes marked in tenths of a milliliter
• Round all dosing instructions to the nearest 0.1, 0.5, or 1 mL
• Provide education using hands-on demonstration and return demonstration
• Consider using picture-based education if low health literacy is a possibility
• Use the following guidelines when calculating pediatric doses

  • Most pediatric medications are ordered in milligrams per kilogram(mg/kg). Therefore, weigh the patient in kilograms before administering medications. Avoid converting the patient's weight from pounds to kilograms to prevent errors.
  • Pediatric doses are usually a lot smaller than adult doses for the same medication. You frequently use micrograms and small syringes (e.g., tuberculin or 1 mL)
  • IM doses are very small and usually do not exceed 1 mL in small children or 0.5 mL in infants
  • Subcutaneous dosages are also very small and do not usually exceed 0.5 mL
  • Most medications are not rounded off to the nearest tenth. Instead they are rounded to the nearest thousandth
  • Measure dosages that are less than 1 mL in syringes that are marked in tenths of a milliliter if the dosage calculation comes out even and does not need to be rounded. Use a tuberculin syringe for medication preparation when the medication needs to be rounded to the nearest thousandth
  • Estimate the patient's dose before beginning the calculation; label and compare the answer with the estimate before preparing the medication
  • To determine if a dose is safe before giving the medication, compare and evaluate the amount of medication ordered over 24hours with the recommended dosage
• The steps involved in calculating an individualized dose are as follows

  • Convert pounds to kilograms
  • Determine the drug dose per body weight by multiplying drug dose × body weight × frequency
  • Choose a method of drug calculation to determine the amount of medication to administer
• Sometimes the body surface calculation may be used instead of body weight to individualize the medication dosage. It is considered to be the most accurate method of calculating a child's dose
• Body surface area


  Determined by using a nomogram and the child's height and weight
• Regardless of the method used to determine the rate, the nurse should have the following information before calculating the flow rate


  • the volume to be infused
  • the drop factor of the infusion set
  • the time frame or how long to infuse the fluid
• Calculating milliliters per hour


  1. Basic formula

  2. Ratio and proportion/ fractional equation
• Calculating drops per minute

  1. Basic formula

  2. Ratio and proportion
• Rounding rules


  • Tablets and caplets can be rounded to the nearest half if they are scored
  • Some tablets are scored in fourths. In this case, the dosage can be rounded to the nearest fourth
  • Tablets and caplets that are extended release, sustained release, controlled release, or enteric coated should not be split because splitting or crushing these preparations destroys the properties that render the drug long lasting. For this reason, capsules are rounded to the nearest whole number
  • Liquid drugs can be rounded to the nearest tenth; the exception to this rule is when calculating dosages of drops, which are rounded to the nearest whole number
• When rounding, determine how many places beyond the decimal point are appropriate. The general rounding rules are


  • If a number to the right of the digit needs to be rounded and is 4 or less, round down
  • If a number to the right of the digit needs to be rounded and is 5 or greater, round up
• The medication order indicates that the medication is to be given immediately and only once or one-time order is for medication to be given once at a specified time may or may not have a termination date
• A standing order may be carried out indefinitely (e.g., multiple vitamins daily) until an order is written to cancel it, or it may be carried out for a specified number of days or as-needed order, permits the nurse to give a medication when, in the nurse's judgment, the client requires it
• A physician usually determines the client's medication needs and orders medications, although in some settings nurse practitioners and physician assistants now order some drugs