Narcotic infusion Calculation

1. Hi,

I am going to be doing some volunteer nursing in Africa and they have sent me a medication calculation quiz to fill out and I am stuck on one question since I haven't had to do this type of med calculations in a long time. I was wondering if I could get some assistance with it.

IV morphine infusion (this is the standard morphine drip order)
Use 50mL syringe: add 1mg/kg morphine and total to 50ml with NaCl 0.9% (max 50mg/50mL).
Run at 10-40mcg/kg/hr=0.5-2ml/hr (run as per anesthesia order).

Question: Your last patient has come back from PACU with a morphine infusion. He weighs 42 kg, so PACU has mixed 42mg morphine in 50mL normal saline for syringe pump infusion. (See above for standard morphine drip orders)

a. What is the concentration of your infusion in mg/mL?

b. The doctor has ordered 20-60 mcg/kg/hour. What is your dose range in mL/hour?

c. You are allowed to give your patient a 1-3mL bolus every 15 minutes if needed for pain, with a 10mL maximum. How many milligrams of morphine would you be giving with each 3mL bolus?

For a) I got 0.84mg/mL but not sure if that is correct. Then for b and c I am lost on where to start. If I could get some assistance on what calculation to use to help answer these questions, that would be great. I really need to understand how to solve these questions, not just get the answers.

Thanks
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