Therapeutics calculations 3

Heparin (subcutaneous) example Order: Heparin 4000 units subcut q8h How many mL will you administer? A. B. C. D.

A. 4000 units/1000 units x 1 mL B. 4000 units/5000 units x 1 mL C. 4000 units/10000 units x 1 mL D. 4000 units/20000 units x 1 mL

IV Fluids (1000 mL = 1 L) (must know)Basic ml/hr (Infusion Pump) •Order 500 mL of 0.9% NS over 2 hours •Rate in mL/hr: 500 mL / 2 hours = 250 mL/hr •Order: Hespan 525 mL to be infused over 3 hours •Rate in mL/hr: •Order: 360 mL PRBCs over 4 hours •Rate in mL/hr:

250 mL/hr 175 mL/hr 90 mL/hr

1 kg = lbs •1 in = cm •1 lb = oz •1 g = mg •1 mg = mcg

1 kg = 2.2 lbs •1 in = 2.54 cm •1 lb = 16 oz •1 g = 1000 mg •1 mg = 1000 mcg

IV fluids-gtt/min 1 L of LR over 5 hrs •Calculate mL/hr = _____ •Calculate gtts/min with the following drop factors: •10 gtt/mL •15 gtt/mL •20 gtt/mL •60 gtt/mL

1 L = 1000 mL 200 mL/hr 33 gtt/min 50 gtt/min 67 gtt/min 200 gtt/min

Max volume of IM injection

3ml/site

Oder: Lipitor 40 mg po daily Avial: Lipitor 10 mg, 20mg, and 20 mg

* use the least

gtt/min

-always round to the nearest whole number

Max and Min for deltoid

0.5-1ml

min and max volume of a subcutaneous injection

0.5-2 mL

Calculate I&O for 8-hour shift Intake •3 oz ice chips •1 cup coffee •¾ cup milk •1 cup oatmeal •4 oz orange juice •IV: NS at 50 mL/hr Output •325 mL urine •25 mL JP drain •55 mL chest tube •1 small bowel movement

1 oz = 30 mL Ice = 50% = 45 mL 1 cup = 8 oz = 240 mL ¾ of 8 oz = 6 oz = 180 mL Oatmeal is not liquid at room temperature 4 oz = 120 mL 50 mL x 8 hr shift = 400 mL

IV Fluids - gtt/min •Order: IV NS at 125 mL/hr •Calculate gtt/min with the following drop factors: •Must ALWAYS round to whole number 10 gtt/mL 15 gtt/mL 20 gtt/mL 60 gtt/mL

10 gtt/mL 125 mL x 10 gtt = 21 gtt/min 60 min mL 15 gtt/mL 125 mL x 15 gtt = 31 gtt/min 60 minmL 20 gtt/mL 125 mL x 20 gtt = 42 gtt/min 60 min mL 60 gtt/mL 125 mL x 60 gtt = 125 gtt/min 60 min x mL

Units calc (ANS) Order: epoetin 4500 units subcut three times a week. •Available: see label •How many mL will you administer per dose? (Round to the nearest tenth) •How many units in a week?

4500 units/10,000 units x mL = 0.45 mL = 0.5 mL (rounded to tenth) 4500 units x 3 = 13,500 units

IV fluid •Order: ascorbic acid 300 mg in 200 mL of 0.9% NS ordered to be infused over 6 hours. •Calculate mL/hr (round to whole number) • •425 mL of PRBCs to be given over 3 hours. The tubing drop factor is 15 gtt/mL •Calculate mL/hr (round to whole number) •Calculate gtt/min

33 mL/hr 142 mL/hr 35 or 36 gtt/min

IV Fluids - LIB (left in bag) •Order: LR at 125 mL/hr. Left in bag: 625 mL •How many hours are left in the bag? •Order: D5W at 35 mL/hr. Left in bag: 280 mL •How many hours are left in the bag?

5 hrs 8 hrs

Reconsitution (ANS) •Order: penicillin G potassium (Pfizerpen) 250,000 units IM q6h •How many mL will you administer? •See different concentrations based on mL diluent added: •Add 20 mL = 50,000 units/mL •Add 10 mL = 100,000 units/mL •Add 4 mL = 250,000 units/mL Add 1.8 mL = 500,000 units/mL

5 mL 2.5 mL 1 mL 0.5 mL

Units (clac ANS) •Order: dalteparin 5000 international units subcut daily •Available: see label •How many mL will you administer?

5000 units/5000 units x 0.2 mL

Weight based question •Order: Robinul 4 mcg/kg IM × 1 dose •Weight: 158 lbs = ________ kg (round to whole number) •Available: Robinul 0.4 mg/2mL •How many mg will you administer? (round to tenth) How many mL will you administer

72 kg 4 mcg = 0.004 mg 0.288 mg = 0.3 mg 1.5 mL

Weight based question •Order: netilmicin sulfate (Netromycin) 2 mg/kg q8h IM •Patient weighs 174 lbs = ______ kg (round to tenth) •Available: netilmicin 100 mg/mL •How many mg should the patient receive per dose? (round to whole number) •How many mL should the patient receive per dose? (round to tenth) •How many mg should the patient receive per day? •How many mL should the patient receive per day?

79.1 kg 158 mg per dose 1.6 mL per dose 474 mg per day 4.8 mL per day

Reconstitution - IM (ANS) •Order: Vancocin 500 mg oral q12h •How much diluent will be added to the bottle? •What is the concentration after reconstitution? •How many mL will you administer per dose? •How many mL will you administer per day?

Diluent: 20 mL Concentration: 250 mg / 5 mL 500 mg/250 mg x 5 mL = 10 mL per dose 10 mL x 2 = 20 mL per day

oral pill conversion •Order: levothyroxine (Synthroid) 0.1 mg po STAT •Drug available: levothyroxine 50 mcg tabs How many tablets will you administer?

•0.1 mg = _____ mcg

Converion cheat sheet weight, height, mg, g

•1 kg = 2.2 lbs •1 in = 2.54 cm •1 lb = 16 oz •1 g = 1000 mg •1 mg = 1000 mcg

convert the following •1 tsp = mL •3 tsp = tbsp •1 tbsp = mL •1 oz = ? mL •1 L = mL •1 cup = ? fl ?oz •1/150 gr = 1 grain=

•1 tsp = 5 mL •3 tsp = 1 tbsp •1 tbsp = 15 mL •1 oz = 30 mL = 2 tbsp = 6 tsps •1 L = 1000 mL •1 cup = 8 fl oz = 240 mL •1/150 gr = 0.4 mg 1 grain= 60 mg

liquid and grain conversion cheat sheet

•1 tsp = 5 mL •3 tsp = 1 tbsp •1 tbsp = 15 mL •1 oz = 30 mL = 2 tbsp = 6 tsps •1 L = 1000 mL •1 cup = 8 fl oz = 240 mL •1/150 gr = 0.4 mg 1 grain= 60 mg

military time •11:07 PM = •5:43 AM = •12:00 AM = •1630 = ________________ •2:45 PM = ________________

•11:07 PM = 2307 in military time •5:43 AM = 0543 in military time •12:00 AM = 0000 or 2400 in military time •1630 = ______4:30PM________ •2:45 PM = ___1445_____________ •Military time requires 4 digits: 2 for the hour and 2 for the minutes. NO colon, AM, or PM

Heparin (subcutaneous)

•Available as single- or multi-dose vial •Check drug label for dose strength or concentration of total volume •1-mL vial: 20,000 USP units is 20 times more concentrated than 1000 •Heparin flushes are different concentrations and should NEVER be switched Remember Chasing Zero??

Macrodrip

•Deliver larger drops per mL •10, 15, 20 gtt/mL •For rates 100 mL/hr or greater

IV Fluids - gtt/min Microdrip

•Deliver small drops per mL •60 gtt/mL •For rates less than 100 mL/hr

Reconstituting Example IM Injection, answer •Order: ampicillin/sulbactam (Unasyn) 1 g IM q8h •Available: See label •Unasyn 3 g vial equals__________ •How many mL of Unasyn would you administer per dose?'

•Order: ampicillin/sulbactam (Unasyn) 1 g IM q8h •Available: See label (no instructions for IM) •Add 3.6 mL of diluent to the vial; drug and diluent equals 4 mL •Unasyn 3 g vial equals__________ (after reconstituted) •FINAL dose in vial after reconstitution: 3 g / 4 mL •How many mL of Unasyn would you administer per dose? Now you can calculate dose (see Order): D/H x V •1 g x 4 mL = 1.3 mL (round to tenth) 3 g