Magnesium Sulfate Dosage Calculations Practice Questions

1. A 34-week pregnant patient with eclampsia is ordered a 4g IV magnesium sulfate loading dose over 20 minutes. You are supplied with a 4g/100mL IV bag. What is the infusion rate (mL/hr)?

           A. 200 mL/hr
           B. 180 mL/hr
           C. 400 mL/hr
           D. 300 mL/hr
   The answer is: D. 300 mL/hr

    
2. A patient is 35 weeks pregnant and has developed eclampsia. The healthcare provider orders IV magnesium sulfate. The provider wants the patient to have a loading dose of 2 g over 20 minutes. You’re supplied with a 4g/100 mL bag. Then a maintenance infusion of 2 g/ hr, and you’re supplied with a 20g/500 mL bag. Determine the flow rates of the loading dose and maintenance dose (mL/hr).
   
   A. loading dose: 150 mL/hr, maintenance: 25 mL/hr
   
   B. loading dose: 400 mL/hr, maintenance: 75 mL/hr
   
   C. loading dose: 150 mL/hr, maintenance: 50 mL/hr
   
   D. loading dose: 250 mL/hr, maintenance: 100 mL/hr
   
   The answer is C. loading dose: 150 mL/hr, maintenance: 50 mL/hr
   
3. A 30-week pregnant patient with preeclampsia is ordered a 6g IV magnesium sulfate loading dose over 30 minutes. You are supplied with a 20g/500mL IV bag. What is the infusion rate (mL/hr)?
   
   A. 800 mL/hr
   
   B. 300 mL/hr
   
   C. 1200 mL/hr
   
   D. 1000 mL/hr
   
   The answer is B: 300 mL/hr
4. A 28-week pregnant patient with eclampsia is ordered a 5g IV magnesium sulfate loading dose over 30 minutes. You are supplied with a 20g/500mL IV bag. What is the infusion rate (mL/hr)?
   
   A. 250 mL/hr
   
   B. 200 mL/hr
   
   C. 350 mL/hr
   
   D. 150 mL/hr
   
   The answer is A: 250 mL/hr
5. A patient is 31 weeks pregnant and has developed eclampsia. The healthcare provider orders IV magnesium sulfate. The provider wants the patient to have a loading dose of 5 g over 20 minutes. You’re supplied with a 20g/500 mL bag. Then a maintenance infusion of 1 g/ hr, and you’re supplied with a 40g/500 mL bag. Determine the flow rates of the loading dose and maintenance dose (mL/hr).
   
   A. loading dose: 375 mL/hr, maintenance: 12.5 mL/hr
   
   B. loading dose: 25 mL/hr, maintenance: 50 mL/hr
   
   C. loading dose: 125 mL/hr, maintenance: 25 mL/hr
   
   D. loading dose: 500 mL/hr, maintenance: 12.5 mL/hr
   
   The answer is A: A. loading dose: 375 mL/hr, maintenance: 12.5 mL/hr
6. A patient is 28 weeks pregnant and has developed eclampsia. The patient has received a 4 g loading dose that was infused over 20 minutes. Now, the healthcare provider orders a 1 g/hr maintenance infusion of IV Magnesium Sulfate. You’re supplied with a 20 g/500 mL IV bag of this medication. What is the rate of infusion for the maintenance order?
   
   A. 50 mL/hr
   
   B. 75 mL/hr
   
   C. 25 mL/hr
   
   D. 100 mL/hr
   
   The answer is C: 25 mL/hr
7. A patient is 32 weeks pregnant and has developed eclampsia. The patient has received a 5 g loading dose that was infused over 30 minutes. Now, the healthcare provider orders a 2 g/hr maintenance infusion of IV Magnesium Sulfate. You’re supplied with a 10 g/250 mL IV bag of this medication. What is the rate of infusion for the maintenance order?
   
   A. 75 mL/hr
   
   B. 100 mL/hr
   
   C. 25 mL.hr
   
   D. 50 mL/hr
   
   The answer is D: 50 mL/hr
8. A patient is 36 weeks pregnant and has developed eclampsia. The patient has received a 6 g loading dose that was infused over 20 minutes. Now, the healthcare provider orders a 1 g/hr maintenance infusion of IV Magnesium Sulfate. You’re supplied with a 40 g/500 mL IV bag of this medication. What is the rate of infusion for the maintenance order?
   
   A. 25 mL/hr
   
   B. 12.5 mL/hr
   
   C. 50 mL/hr
   
   D. 75 mL/hr
   
   The answer is B: 12.5 mL/hr
9. A 32-week pregnant patient with severe preeclampsia is ordered a 4g IV magnesium sulfate loading dose over 30 minutes. You are supplied with a 20g/500mL IV bag. What is the infusion rate (mL/hr)?
   
   A. 200 mL/hr
   
   B. 250 mL/hr
   
   C. 300 mL/hr
   
   D. 180 mL/hr
   
   The answer is A: 200 mL/hr
10. A patient is 39 weeks pregnant and has developed eclampsia. The patient has received a 4 g loading dose that was infused over 30 minutes. Now, the healthcare provider orders a 2 g/hr maintenance infusion of IV Magnesium Sulfate. You’re supplied with a 20 g/500 mL IV bag of this medication. What is the rate of infusion for the maintenance order?
    
    A. 25 mL/hr
    
    B. 75 mL/hr
    
    C. 50 mL/hr
    
    D. 100 mL/hr
    
    The answer is C: 50 mL/hr

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