dosage calc help for students

Published Apr 18, 2008

1,010 Posts

Specializes in Med/Surg, Home Health.

I was thumbing thru my stuff from school and found this. Thought it may help some of you. I copied/pasted it from a word document. It may look garbled, I hope not. If anyone wants the word document (will look better and make more sense) just let me know. The fractions dont look quite right here.

DOSAGE CALCULATIONS

V = Volume

T = Time in minutes (not hours)

C = Calibration (drop factor) (gtt/ml)

R = Rate (gtt/min)

*NO PUMP

V/T x C = R

Example: Calculate flow rate for 1200 m of NS to be infused in 6 H with dropfactor of 15 gtt/ml.

1200 ml/ X 15 gtt/ = R  18000/ = 50 gtt/min (rate)

360 min 1 ml 360

Example: 250 ml LR IV to infuse in 5 H with dropfactor 60 gtt/ml.

250 ml/ X 60 gtt/ = R  15000/ = 50 gtt/min (rate)

300 min 1 ml 300

*WITH PUMP

V/T = R (Total ml/total hour = rate)

Example: Infuse 250 ml over next 2 H by infusion pump.

250 ml/ = 125 ml/hr

Example: Infuse 50 ml in 30 minutes by infusion pump

50 ml/ = 100 ml/hr

0.5 h

or by ration proportion:

50 ml/ = x ml/  30x/ = 3000/  x = 100 ml/hr

30 m 60 min 30 30

*TOTAL INFUSION TIME

TOTAL VOLUME = TOTAL HOURS

ML/HR

Example: IV of 500 ml was hung at 8:00. Ordered to run at 75 ml/hr. What time will bag empty.

500ml = 6.666. It will take 6.666 hours to infuse. So take the 0.666 and multiple by 60 (minutes) to get the total of that hour (39.96). Round that number to 40. So the total time will be 6 hours and 40 minutes. Add that to 8:00 and the time will be 14:40.

*BODY SURFACE AREA w/ RECOMMENDED DOSE

MG/M2 X M2 = CHILD DOSE

Example: Vincristine IV for a child who weighs 28 kg and 100 cm tall.

BSA = 0.9 m2

Supply: Vincristine 2mg/2ml

Recommended dose is 2mg/m2

2 mg x 0.9 = 1.8 mg

2 mg/ = 1.8 mg/  2x/ = 3.6/  dose is 1.8 ml

2 ml x 2 2

*BODY SURFACE AREA WITH NO RECOMMENDED DOSE, WITH ADULT DOSE

BSA of child x Adult Dose = Child dose

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