A nurse is preparing to administer diltiazem IV 0.25 mg/kg IV bolus given over 2 min to a client who has atrial fibrillation and weighs 154 lb. Available is diltiazem IV injection 25 mg/5 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 calculate the volume of diltiazem to administer, we first need to determine the appropriate dose based on the client’s weight. The prescribed dose is 0.25 mg/kg.
- Convert the client’s weight from pounds to kilograms:
[
\text{Weight in kg} = \frac{154 \text{ lb}}{2.2 \text{ lb/kg}} \approx 70 \text{ kg}
] - Calculate the required dose of diltiazem:
[
\text{Dose} = 0.25 \text{ mg/kg} \times 70 \text{ kg} = 17.5 \text{ mg}
] - Determine the volume of diltiazem IV injection needed:
The available concentration of diltiazem is 25 mg in 5 mL. To find out how much volume corresponds to 17.5 mg, we can set up a proportion:
[
\frac{25 \text{ mg}}{5 \text{ mL}} = \frac{17.5 \text{ mg}}{x \text{ mL}}
] Rearranging gives:
[
x = \frac{17.5 \text{ mg} \times 5 \text{ mL}}{25 \text{ mg}} = \frac{87.5}{25} = 3.5 \text{ mL}
]
Thus, the nurse should administer 3.5 mL of diltiazem.
Explanation
In this scenario, the nurse is treating a client with atrial fibrillation, a condition where the heart’s electrical signals become disorganized, leading to an irregular heartbeat. Diltiazem, a calcium channel blocker, is often used to control the heart rate and improve rhythm. The calculation begins with converting the patient’s weight, which is essential to ensure the correct dose based on their body mass.
The method involves using a simple multiplication to find the total mg needed and then a proportional relationship to convert mg into mL based on the available concentration. This ensures the nurse administers the precise amount of medication, which is critical for patient safety, especially in scenarios involving intravenous administration where dosages must be accurate to avoid complications.