A nurse is preparing to administer morphine 0.2 mg/kg IM to a client who weighs 99 lb. Available is morphine injection 10 mg/mL. How many mL should the nurse administer? (Round the answer to the nearest tenth. Use a leading zero if it applies. Do not use a trailing zero.)
The Correct Answer and Explanation is:
To solve this medication dosage problem, follow a systematic approach by breaking it down into steps.
Step 1: Convert the client’s weight from pounds to kilograms
The formula for converting pounds to kilograms is:1 kg=2.2 lb1 \, \text{kg} = 2.2 \, \text{lb}1kg=2.2lb
The client weighs 99 lb. To convert this to kilograms:99 lb2.2=45 kg\frac{99 \, \text{lb}}{2.2} = 45 \, \text{kg}2.299lb=45kg
Step 2: Calculate the required dose of morphine
The order is to administer 0.2 mg of morphine per kilogram of the client’s body weight. Since the client weighs 45 kg, the required dose of morphine is:0.2 mg/kg×45 kg=9 mg0.2 \, \text{mg/kg} \times 45 \, \text{kg} = 9 \, \text{mg}0.2mg/kg×45kg=9mg
The client needs 9 mg of morphine.
Step 3: Determine how much volume to administer
The available morphine concentration is 10 mg/mL. This means each mL contains 10 mg of morphine. To find out how many mL the nurse should administer, divide the required dose by the concentration:9 mg10 mg/mL=0.9 mL\frac{9 \, \text{mg}}{10 \, \text{mg/mL}} = 0.9 \, \text{mL}10mg/mL9mg=0.9mL
So, the nurse should administer 0.9 mL of morphine.
Step 4: Rounding and using appropriate notation
In this case, rounding to the nearest tenth doesn’t change the answer since it is already 0.9 mL. The leading zero is correctly used before the decimal point, and no trailing zero is added after 0.9.
Explanation:
To ensure accurate dosing, nurses must follow a structured approach: weight conversion (especially in pediatric or precise dosing), dosage calculations based on the client’s body weight, and understanding medication concentrations. In this scenario, the client’s weight conversion from pounds to kilograms is critical to calculating the appropriate dose per kilogram. Finally, the nurse determines the appropriate volume to administer by dividing the total required dose by the available concentration, ensuring safe and effective medication administration.