An infant weighing 6 pounds 3 ounces has morphine 0.5 mg IV q 2 hours prn ordered for post op pain. The recommended dosage for a child is 0.1-0.2 mg/kg/dose q2-4 hours prn. Prove mathematically the ordered dose by the physician (mg/kg/dose) and is it safe to give.
The Correct Answer and Explanation is:
To determine if the physician’s ordered dose of morphine for the infant is within the recommended range, we need to calculate the infant’s weight in kilograms and the dosage in milligrams per kilogram (mg/kg).
Step 1: Convert the infant’s weight from pounds and ounces to kilograms.
- 1 pound = 16 ounces, so 6 pounds 3 ounces = 6 + (3/16) pounds.
- 3 ounces is 3/16 of a pound: 3 ounces=0.1875 pounds3 \text{ ounces} = 0.1875 \text{ pounds}3 ounces=0.1875 pounds Therefore: 6 pounds3 ounces=6.1875 pounds6 \text{ pounds} 3 \text{ ounces} = 6.1875 \text{ pounds}6 pounds3 ounces=6.1875 pounds
- Convert pounds to kilograms by multiplying by 0.4536 (since 1 pound = 0.4536 kg): 6.1875 pounds×0.4536=2.806 kg6.1875 \text{ pounds} \times 0.4536 = 2.806 \text{ kg}6.1875 pounds×0.4536=2.806 kg
Step 2: Calculate the recommended dose range.
The recommended dosage is 0.1-0.2 mg/kg per dose.
For a weight of 2.806 kg, the dose range is calculated as:
- Lower limit: 0.1 mg/kg×2.806 kg=0.2806 mg0.1 \text{ mg/kg} \times 2.806 \text{ kg} = 0.2806 \text{ mg}0.1 mg/kg×2.806 kg=0.2806 mg
- Upper limit: 0.2 mg/kg×2.806 kg=0.5612 mg0.2 \text{ mg/kg} \times 2.806 \text{ kg} = 0.5612 \text{ mg}0.2 mg/kg×2.806 kg=0.5612 mg
Thus, the safe dosage range for this infant is 0.2806 mg to 0.5612 mg per dose.
Step 3: Compare the physician’s order to the recommended range.
The physician has ordered 0.5 mg of morphine per dose. This dose falls within the recommended range of 0.2806 mg to 0.5612 mg.
Step 4: Conclusion
Since the ordered dose of 0.5 mg is within the safe range of 0.2806 mg to 0.5612 mg, it is safe to administer this dose to the infant.
Explanation:
Calculating medication dosages for infants requires attention to both weight and recommended dosing guidelines. Morphine is prescribed for pain relief in post-operative cases, and its dose must be tailored to avoid underdosing, which may lead to insufficient pain relief, or overdosing, which could cause dangerous side effects like respiratory depression.
The conversion of the infant’s weight to kilograms ensures accuracy in applying the recommended dose range, as medication dosages are typically based on body weight in metric units (mg/kg). The calculation confirms that 0.5 mg of morphine is within the recommended range for an infant of this weight, meaning it is both appropriate and safe to administer this amount.