MEDICAL MATH. Help for the Mathematically Challenged

Transcription

1 MEDICAL MATH Help for the Mathematically Challenged

2 The Metric Basics Set up on a scale of ten All units use the same scale Meter = distance Liter = volume Gram = weight

3 For Our Purposes One cubic centimeter (cc) = One milliliter (ml) = One gram (gm)..more or less..

4 What is a Cubic Centimeter? A cube which measures 1 cm wide by 1 cm high by 1 cm deep. Or, 1 cm x 1 cm x 1cm. (1 cm = ½ inch, almost)

5 When you fill a 1 ml syringe with fluid and empty it into the cube, the amount in the syringe will fill the cube. =

6 Then when weigh you dump the contents of the cube onto a gram scale, the amount of liquid in the cube will weigh 1 gram = =

7 Metric Prefixes kilo = 1000 hecto = 100 deka = 10 Basic unit meter, liter, gram deci = one tenth (1/10) centi = one one-hundredth (1/100) milli = one one-thousandth (1/1000)

8 Most Commonly Used Units of Measure cc = cubic centimeter (cm³) ml = milliliter g = gram kg = kilogram mg = milligram

9 Commonly Used Conversions 1000 milligrams (mg) = 1 gram (g) 1000 g = 1 kilogram (kg) 1000 milliliter (ml) = 1 liter

10 Rough Equivalents 1 ml = 15 drops 1 tsp = 4.5 ml 1 Tbs = 15 ml 1 fluid ounce = 30 ml 1 ounce = 30 g (really 28.35g) 1 pound = 450 g (really 454g) =.454 kg 2.2 lbs = 1 kg

11 Fractions and Decimals Your brain has thought in fractions NOW!!!! ½ = ¼ = ¾ = 1/10 = 1/100 = 1/1000 =

12 To make metric to metric conversions just move the decimal point!! Grams to kilograms 1200 g red tail hawk Move the decimal 3 to the left (tens, hundreds, thousandths) 1.2 kg red tail hawk

13 Time for calculators Or phones

14 An example closer to home kg great horned owl to pounds 1 kg = 2.2 lbs 1.7 kg x 2.2 lbs 1 kg 1.7 x 2.2 lbs = 3.74 lbs

15 A 15 lb raccoon to grams 454 g = 1 lb 15 lb x 454g 1 1lb 15 x 454 g = 6810 g

16 Or, the same raccoon directly to kg 454 g = 1 lb and 2.2 lbs = 1 kg 15 lb x 1 kg lb 15 lb x 1 kg = 6.8 kg 2.2 lb 15 = 6.8 kg g = 6.8 kg

17 Goals for Today Medication Doses Fluid Calculations Caloric Calculations

18 Medications Body Weight x Dose Rate x Strength = Dose BW from your chart Dose rate from your veterinarian Strength from the medication bottle

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22 Common Abbreviations Frequency SID = once daily BID = twice daily TID = three times daily QID = four times daily q8hr = every eight hours q3d = every three days

23 Routes of Administration IM = IV = ID = SQ = PO = intramuscular intravenous intradermal subcutaneous (also SC or SubQ) per os (by mouth)

24 Routes of Administration-Veterinary IC = intracardiac IO = intraosseous IP = intraperitoneal

25 Patient is a Virginia opossum. Weight 450 g Dose rate from your veterinarian Strength from bottle 250 mg/5ml 10 mg/lb BID BW x dose rate x strength = dosage in cc s 450 g x 10 mg x 5 ml = dosage 1 lb 250 mg 450 g x 10 mg x 5 ml = dosage 454 g 250 mg = 0.2 cc BID

26 Another way to look at the same problem.. The veterinarian tells you to give 10 mg/lb BID. At 450 g, the opossum is just about a pound, and therefore should receive about 10 mg. If the strength on the bottle says 250 mg/5 ml, then 50 mg/ 1 ml. That means that each.10 ml (cc) contains 5 mg. (.10 x 50 = 5) So,.2 cc contains 10 mg.

27 Try another. Red-tail hawk weighs 1 kg Veterinarian says give 25 mg/kg BID Bottle indicates 100 mg/ml 1 kg x 25mg x 1 ml 1 kg 100mg = cc s 25 ml =.25 cc BID 100

28 Or The veterinarian says to give 25 mg BID. The bottle indicates 100 mg/ml Look at the syringe and work the problem So, ½ ml yields 50 mg and ¼ ml yields 25 mg Give the hawk ¼ cc BID

29 Fluids Go to the Fluid Therapy Workshop for complete instructions. Just the math

30 Daily Fluid Requirements BW in g x 5% = cc s per day for maintenance PLUS BW in g x % dehydration = cc s per day for deficit EQUALS Total fluids for 24 hrs

31 Back to the 1 kg red-tail hawk assuming a 10% dehydration. BW in g x 5% = cc 1000 x.05 = 50 cc Add to that BW in g x % dehydration = cc 1000 x.10 = 100 cc So, 50 cc cc = 150 cc total

32 Try Another. Back to the 450 g Virginia opossum assuming an 8% dehydration. 450g x.05 = 22.5 cc (maintenance) Add to that 450 g x.08 dehydration = 36 cc (deficit) 22.5 cc + 36 cc = 58.5 cc

33 For help (and a cheat sheet) NWRA Quick Reference Pages 97 through 102 Pages 116 through 118

34 Caloric Calculations Again, go to the Nutrition Workshop for the details. Again, just the math.

35 MEC Depending upon which reference material you select. Minimum Energy Cost Metabolic Energy Coefficient Simply, the daily energy requirement for a healthy adult animal at rest.

36 Caloric requirement formula Constant x BW.75 (kg) x = Kcals Kcals =Daily Energy Requirement in kilocalories

37 So, what s that?!?!?!? BW.75 Body weight to the.75 power (or ¾ power) Time for a quick algebra review..

38 Numbers powers Squared a number multiplied by itself is a number squared. 2 x 2 = = 4 Cubed a number multiplied by itself and then again is a number cubed. 2 x 2 x 2 = = 8

39 Try a few. 4 2 = 4 x 4 = = ½ 2 = 5 x 5 = 25 ½ x ½ = ¼.25 2 =.25 x.25 =.0625

40 Square root of numbers Two identical numbers, when multiplied together give you the number with which you started. If 2 x 2 = 4 or 2 2 = 4 Then 4 = 2 Most calculators have a key. Enter your number (36), then press the key for the answer (6).

41 Try a few. 25 = 100 = = 3 50 = 7.07

42 You will need these to work the formula Passerine 129 Constants Non-passerine 78 Placental mammal 70 Non-placental mammal 49 Reptile 10 Refer to aforementioned Nutrition Workshop

43 So, back to calculations Constant x BW.75 (kg) x = Kcals So, how do you do.75?? Some calculators have an X y key. Enter your number (2), press X y, then enter the power (.75), then = (1.68). Without that X y key.. Enter your number (2), multiply it by itself three times (2 x 2 x 2 = 8). Then take the square root of that number two times.

44 Let s try a few 1.75 = = = =

45 A few problems Back to the 450 g Virginia opossum 49 x = Kcals 49 x.55 = Kcals Kcals daily

46 Patient is a 90 g American robin 129 x.09 kg.75 = Kcals 129 x.16 = Kcals 20.6 Kcals

47 Just to add confusion MEC is minimum requirement. Most of the animals in our care need more than the minimum level.

48 Multipliers for caloric requirements Healthy adult: MEC x 1.5 Debilitated adult: MEC x 2.5 Healthy young: MEC x 4 Debilitated young: MEC x 5 Or thereabout, depending on your reference source and the workshop instructor.

49 So what does that mean????? The Nutrition Workshop!!! Attend a workshop on nutrition to discover how many Kcals each item of food contains and how to mix those foods to provide adequate nutrition for every type of patient, every age group and each level of debilitation.

50 For help (and a cheat sheet) NWRA Quick Reference Pages 104 through 107 Pages 119 through 120

51 References Quick Reference - Third edition Compile and edited by Erica A. Miller, DVM National Wildlife Rehabilitators Association IWRC Basic Wildlife Rehabilitation 1AB - Jan White, DVM International Wildlife Rehabilitation Council NWRA Proceedings Volume 6, 1987 Secrets of Medical Math, Mark A. Pokras, DVM Exotic Animal Formulary Third edition James W. Carpenter

52 Thanks Erica A. Miller, DVM Tri-State Bird Rescue and Research Newark, DE Mark A. Pokras, DVM Tufts University School of Veterinary Medicine North Grafton, MA

53 Diane Nickerson Mercer County Wildlife Center 1748 River Road Titusville, New Jersey

54 That s All Folks!!