First, convert pounds to kg,
220 lb : X = 2.2 lb : 1 kg = 100 kg.
Next, calculate the dosage per minute,
3 mcg/kg/min x 100 kg = 300 mcg/min.
Now, Convert mcg/min to mcg/hour,
300 mcg/min x 60 min = 18,000 mcg/hour.
Convert mcg/hr to mg/hour, 18,000 mcg/hr = 18.0 mg/hour.
Calculate the rate,
400 mg : 250 ml = 18 mg : X ml 400X = 4500 X = 11.25 = 11.3 ml.
So, 18 mg/11.3 ml should be infused at 11.3 ml/hour