Student form dosage calc problems PDF

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OB math calculations

1. A patient is ordered Ancef for treatment of GBS positive cultures. The patient is to receive a bolus of 2g followed by a maintenance dose of 1g every 8 hours. How many g will the patient receive in the first 24 hours of treatment? 1g = 8 hrs X g = 24 hrs 8x = 24x = 24/8 = 3g 2. A patient with a history of opioid abuse is on Methadone, with a daily dose of 60mg. The doctor has placed an order for the patient to receive a dose every 4 hours. How many mg will the patient receive at each dose? 60 mg = 24 hrs X mg = 4hrs 24x = 60*4 X = 240/24 = 10mg 3. An African American patient with a history of two preterm births is to receive betamethasone to stimulate fetal surfactant production. The provider order reads: 12.5 mg betamethasone IM every 24 hours for two doses. The betamethasone vial is labeled as 25 mg/ml with a total volume of 1 ml. How many ml will the nurse draw up into the syringe for each dose ordered? 25 mg = 1 ml 12.5 mg = x 25x = 12.5 X = 12.5/25 = 0.5 ml 4. An obese patient who weighs 198 pounds has been diagnosed with a deep vein thrombosis (DVT) in her left leg and needs to be heparinized. The provider orders a bolus of 80 units/kg to be infused now and followed by a maintenance infusion. Solution is labeled as 25,000 units heparin/1000 ml D5W

a. Order: Heparin bolus at 80 units/kg x 1. 80 units * 198/2.2 = 7200 units

b. Order: Run a maintenance rate of 1500 units per hour. What rate should the infusion pump be set at? How many ml/hr? 25000 u/1000ml = 25 u/ml 1500u by 25 ml = 60 ml/hr Sylvia has a history of pyelonephritis and the Nurse Practitioner decides to start her on daily nitrofurantoin orally. Sylvia requests the liquid formulation, so Dr. Lamascus prescribes 75 mg twice a day as a prophylactic. The nurse instructs her how to take the medication. The suspension label reads 25 mg/5ml. How would you instruct Sylvia to take this medication if she uses a medicine cup labeled for 2 tablespoons (30 ml) at full capacity with increments of tablespoons and corresponding ml? 

How many tablespoons is needed for each dose? How many ml ? 25mg = 5 ml 75mg = x ml 25x = 75*5 X = 375/25 = 15ml = 1 tablespoons

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How many ounces of the suspension will Sylvia need over the next 4 weeks (28 days)?

1oz = 30 ml

x = 30/15 = 0.5 oz

X oz = 15 ml.

0.5 * 28 = 14 oz

5. Nickie comes to the OB office stating she is nauseous and is having difficulty keeping food down. The nurse asks her about her nutrient intake and teaches her to eat small, bland foods such as baked potato without butter, rice, and dry well toasted bread. Nickie requests something else to help her with her nausea. Knowing Nickie ‘s husband is with her, the Nurse Practitioner, Dr. Lamascus orders a 25 mg Promethazine

injection IM now. The nurse obtains the vial of promethazine, checks the expiration date and the label, which says 50 mg/5 ml. How many ml does the nurse need to draw up and inject into Ana’s hip? 50 mg = 5 ml 25 mg = x ml 50x = 25*5 X = 125/50 = 2.5 ml 6. Magnolia is admitted to the hospital at noon with hyperemesis gravidarum. Her serum potassium level is 3.0 and the hospitalist has ordered 20 mEq potassium chloride to be infused over one hour. The solution is labeled 20 mEq / 100 ml NS. What rate would you set the infusion pump to run? 100ml / 1 hr 7. Magnolia has a second order for a 500 ml bolus infusion of Lactated Ringers in 30 mins. At what rate would you set the infusion to run?

500ml/0.5 hr = 1000 ml / 1 hr 8. Magnolia needs to receive a maintenance infusion of LR at 100 ml per hour after the completion of the 500 ml bolus. When will you anticipate replacing the IV solution with a new bag of LR?

After 5 hrs 9. At week 34, Ana begins to show clinical signs of preeclampsia: the urine dipstick shows 2+ protein and she complains of a headache and sees spots. So the obstetrician admits her to the hospital and orders a bolus of 6g magnesium sulfate to be infused over 30 minutes. 

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The solution reads LR 1000 ml with 40 g of magnesium sulfate. o What infusion rate would you set the pump on to deliver the bolus dose? 1000ml = 40 g X ml = 6g 40x = 6*1000 X = 6000/40 = 150 ml /0.5hr A second order reads infuse magnesium sulfate at 2 g per hour. o What infusion rate would you set the pump to deliver 2 g per hour from the same IV solution? 40g = 1000ml 2g = x ml x = 2000/40 X = 50 ml / 1 hr

10. During one the nurse’s hourly assessments, Ana is lethargic, her respirations are 8/minute and her DTRs are absent. The nurse identifies this as magnesium sulfate toxicity and after informing the obstetrician the following is ordered: stat magnesium level, stop the magnesium infusion, calcium gluconate, 1 gm IVP over 3 mins. One hour later her magnesium level is 5.7 mg , therapeutic for preeclampsia (4.7 to 8 mg/dl) but not toxic. The nurse evaluates the intervention. The patient has normal CNS functioning; is alert and oriented; respiratory rate is 16; DTR 2+, and urine output 75 ml so the magnesium sulfate is restarted at 1 g/hr per provider order. With the same solution of 40g/liter, at what rate (ml/hr) would you set the infusion pump? 40 g = 1000ml 1g = x ml X = 1000/40 = 25 ml/hr

11. Ana presents to her 28th week antepartum visit with a blood pressure of 145/88. Last week her blood pressure was 143/84, so the obstetrician ordered some blood work to evaluate for preeclampsia. Serum creatinine was 0.8, Urinalysis did not show any protein, liver enzymes were normal, and her CBC showed platelets to be 200,000. So preeclampsia was ruled out. She will return weekly to monitor her blood pressure and perform a urine dipstick for protein. The nurse has instructed her to call the office or go to the ER if she develops headaches or visual changes. On her 33rd week visit, Ana’s blood pressure was 150/ 88, but still had no other signs of pre-eclampsia, so the obstetrician decides to begin the antihypertensive drug labetolol, a nonselective beta blocker. (Ana does not have asthma). The prescription reads 100 mg labetolol by mouth, three times each day. The available dose is a 200 mg tablet. How many tablets will Ana need the next 3 weeks? 200mg = 1 tab

100 mg = 0.5 tab.

0.5tb * 3 = 1.5 tab / day.

1.5 tab * 21 = 31.5 tab for 3 weeks

12. Stephanie is admitted to Labor and Delivery for induction of labor. She has an order for Lactated Ringers 1000mL over 8 hours. At what rate should the nurse program the pump? 1000ml/8hrs = 125 ml /1 hrs

13. Stephanie’s cervix is examined, and her Bishop score is 8. The provider orders Pitocin to start at 2mu/min. The Pitocin available is 20 units in 1000 mL Normal Saline. What rate should the infusion pump be set at to start this medication? 20 u = 1000ml

100ml = 1 min.

2 u = x ml

1000 ml = x min

X = 2000/20 = 100 ml

x = 1000/100 = 10 min

100ml /10 min

14. After beginning the Pitocin at 2mu/min, the provider orders for the Pitocin to be titrated 1-2mu/min every 30 minutes until contractions are 2-3 minutes apart. The Pitocin available and infusing is 20 units in 1000 mL Normal Saline. How many ml/hr will the nurse increase the rate of infusion for each milliunit increase?

100ml = 10 min 1000 ml = x min X = 10000/100 = 100min = 1000ml in 1.6 hrs 15. Stephanie’s labor is progressing well, and she will be delivering soon. Stephanie has an order for Pitocin 500mu/min for post-delivery bleeding to be administered after delivery of the placenta. The Pitocin available is 30 units in 500 mL Normal Saline. What rate will the nurse anticipate infusing the Pitocin on the infusion pump after delivery? 30 u = 500 ml 500u = x ml X = 500*500/30 = 250000/30 = 8333 ml = 500u in 8333ml 16. Ordered: D5W 50 mL with 20 mEq KCl to infuse at 8 mEq KCl/hr per IV pump. How many mL of solution will you set on your IV pump? 20 meq = 50 ml 8meq = x ml X = 50*8/20 = 400/20 = 20 ml/hr 17. If the nurse gives the postpartum patient a dose of Methylergonovine 400 mcg IM every 5 hours, how many mg is administered in 25 hours?

0.4 mg = 5 hrs X mg = 25 hrs X – 0.4*25/5 = 2mg in 25 hrs 18. A premature baby weighs 2300g at birth. What does the baby weigh in kg? In pounds? 1kg = 1000g X kg = 2300g X = 2300/1000 = 2.3 kg 20. The order is to administer Magnesium Sulfate bolus of 2 g over 30 minutes followed by 1 g/hr. Available is 30 g in 500 mL of D5W. Figure the bolus dose and the maintenance dose in mL/hr.

Bolus:

The pump is set at ___mL/hr , Maintenance: The pump is set at ___mL/hr

2g = 0.5hrs 30 g = x hrs X = 15/2 = 7.5 hrs 30 g = 500 ml 2g = x ml X = 1000/30 = 33.33 ml/ hrs...