Making Medical Math FUN-Griffith - Iowa Veterinary Specialties
Transcript of Making Medical Math FUN-Griffith - Iowa Veterinary Specialties
Making Medical Math fun and EASY!A Veterinary Guide to Medical Math
Jessica Griffith, RVT [email protected] Small Animal ICU Technical Supervisor Iowa State University College of Veterinary Medicine
About Me
! Born and raised in Iowa ! Moved to Michigan in 2011 ! Graduated with AAS in Veterinary
Technology in 2015 ! Worked in private practice ER clinic for 1
year ! Moved back to Iowa in 2016 ! Began working at ISU in the Small Animal
ICU in 2016 ! Became ICU Veterinary Technical
Supervisor in 2018
https://www.bestplaces.net/city/iowa/de_witt http://www.westplainsengineering.com/2012/09/iowa-state-university-college-of-veterinary-medicine-2/
Today’s Medical Math FUNThe Basics
! Converting units ! Weight ! Concentration ! Volume
! Basic drug dose ! IV Fluid rates
! Fluid pumps ! Manual drip rates
! Dextrose Supplementation
Advanced Medical Math! Constant-rate infusions
! Delivery rates ! Pumps ! Manual drip rates
! Electrolyte supplementation
MATH !
" YOU
https://clawguard.com/blogs/clawguard-blog/80377222-is-my-dog-stressed
1. Patient 2. Drug 3. Dose 4. Route 5. Frequency
The 5 “Rights”
“Give 2 capsules twice daily”
“2 drops in
effected eye as
needed”
http://www.worldwhiteweb.net/
Complete Prescription Instructions
“2 drops in effected eye as needed”
Instill 2 drops into the left eye up to every 4 hours as needed for 2
weeks
“Give 2 capsules twice daily”
Give 2 capsules by mouth every 12 hours until gone
Dose vs Dosage
Dose = a specific amount of medication administered at one time • Example: 400 mg (2 capsules) ibuprofen
Dosage = the specific amount, number, or frequency of doses over a period of time • Example: 400 mg ibuprofen every 12
hours for two days Day 1: Day 2:
Conversions to Know
1. pounds kilograms
2. milligrams micrograms
3. grams milliliters
https://www.wikihow.com/Convert-Milliliters-(mL)-to-Grams-(g)
1 kilogram
1 pound
A Few Methods to Write Out Math Equations! Classic Equation
! Lines & Cancelling Units ! 14 kg 2 mg 1 mL 1 kg 10 mg
! Shifting Decimal Places !280 ÷ 1000 = 280.0 = 0.28
= 2.8 mL
https://www.rd.com/culture/math-lessons-real-life/
Pounds Kilograms
!2.2 pounds (lb) = 1 kilogram (kg) !Pounds to kilograms (kg)
! lb ÷ 2.2 = kg
!Kilograms (kg) to pounds !kg x 2.2 = Lb
1 lb. 1 lb.0.2 lb. 1 kg
http://www.mathwatson.com/professional-bathroom-scales.html
Example 1Kilograms to Pounds Pounds to Kilograms
! How many pounds does a 17 kilogram dog weight?
! How many kilograms does a 17 pound dog weigh?
https://www.cuteness.com/article/differences-between-english-british-bulldogs
1 kilogram (kg) = 1000 grams (g)
! Kilograms (kg) to grams (g)
! kg x 1000 = g
! Grams (g) to kilograms (kg)
! g ÷ 1000 = kg
Example 2: How many kilograms does a 578 gram guinea pig weigh?
5 7 8.0 grams
0.578 kilograms
Kilograms
Grams
https://flipboard.com/@kristinapor41nk/guinea-pig-info-k6tgl2vrz
Putting it Together
Example 3: How many pounds does a 0.578 kg guinea pig weigh?
OR
0.578 × 2.2 = 1.27 pounds
Milligrams Micrograms
! 1 milligram (mg) = 1,000 micrograms (mcg) ! 1 microgram (mcg) = 0.001 milligrams (mg)
!Milligrams to micrograms !mg x 1,000 = mcg
!Micrograms to milligrams !mcg ÷ 1,000 = mg
2.18 mg x 1000= 2.180 mcg = 2180 mcg
ExamplesExample 1: How many micrograms of dexmedetomidine are in 0.4 mL of an injectable solution with a concentration of 0.5 mg/mL? 1. Calculate how many milligrams in 0.4 milligrams
2. Calculate how many micrograms are in 0.2 milligrams by multiplying by 1000
= 0.5 mg1 mL
0.4 mL = 0.2 mg
0.200 x 1000 =
200 mcg
2.400 x 1000 = 2400 mcg
Examples
Example 2: How many micrograms are in 2.4 milligrams?
= 2400 mcg
Grams Milliliters Liters Kilograms
Did you know?
Weight to Volume (of Water)
o Grams to milliliters o 1 gram = 1 milliliter
o Liters to kilograms
o 1 liter = 1 kilogram
https://www.guidedogsvictoria.com.au/shop/ https://makeyourbodywork.com/drink-water-to-lose-weight/
8 kg puppy
≈
DrugDoseCalculations
https://spyescapeandevasion.com/blog/2016/08/15/why-ghost-apps-are-so-dangerous/
When cell phone use is encouraged!
Basic Drug Dose CalculationsA 28 pound mixed breed canine needs a 2 milligrams per kilogram dose of furosemide. The available concentration is 5%. What volume will this dog receive per dose?
Concentration % × 10 = mg/mL
5 ×10 = 50 mg/mL
Basic Drug Dose CalculationsA 28 pound mixed breed canine needs a 2 milligrams per kilogram dose of furosemide. The available concentration is 5%. What volume will this dog receive per dose?
1. Convert pounds to kilograms 12.7 kilograms
Basic Drug Dose CalculationsA 28 pound mixed breed canine needs a 2 milligrams per kilogram dose of furosemide. The available concentration is 5%. What volume will this dog receive per dose? 1. Convert pounds to kilograms
12.7 kilograms
2. Multiply by dosage (mg/kg)
Basic Drug Dose CalculationsA 28 pound mixed breed canine needs a 2 milligrams per kilogram dose of furosemide. The available concentration is 5%. What volume will this dog receive per dose?
1. Convert pounds to kilograms 12.7 kilograms
2. Multiply by dosage (mg/kg)
3. Divide by drug concentration (mg/mL) 0.51 milliliters
All Together Now!
28 lbs 1 kg 2 mg 1 mL 2.2 lbs 1 kg 50 mg
Steps: 1. Convert pounds to
kilograms 2. Multiply by dosage
(mg/kg) 3. Divide by drug
concentration (mg/mL)
= 0.51 mLOR
https://weheartit.com/entry/11357611
IV Fluid RatesFluid Pumps
! Need to know: 1. Rate (mL/hr)
2. Volume to be infused (mL)
http://apexx-equipment.com/pre-owned-vet-equipment/iv-pumps/Baxter-Flo-Gard-6200-IV-Pump https://www.adeptomed.com/product/buy-service-rent/hospira-plum-a-11-6 https://heska.com/products/iv-pumps/vet-iv-infusion-pump.aspx?s=0BC104F55A4DD097D3EF5B416513501161B465BC
IV Fluid RatesManual Drip Sets
! Need to know: 1. Rate (mL/hr)
2. Volume to be infused (mL)
3. Drops/mL of fluid line
https://basicmedicalkey.com/basic-intravenous-therapy-calculations/
Components to Calculate Daily Fluid Rates:
1.Maintenance 2.Fluid deficit 3.Ongoing losses
https://www.pepperlaw.com/publications/not-so-simple-math-calculating-the-regulatory-review-period-for-patent-term-extension-2017-05-18/
Calculating Daily Fluid Rates
1. Maintenance – includes normal sensible and insensible losses
https://www.animalbehaviourbusiness.com/wet-greetings/ https://www.akc.org/expert-advice/health/doggie-diarrhea/ https://barkingroyalty.com/dog-panting-and-shaking/
Calculating Daily Fluid Rates
1. Maintenance – includes normal sensible and insensible losses
70×[body weight(kg)0.75]
40-60 mL/kg/day
Calculating Daily Fluid Rates
1. Maintenance 2. Fluid deficit – as assessed using hydration parameters
https://www.fieldandstream.com/blogs/mans-best-friend/2011/06/how-tell-if-your-dog-dehydrated
Calculating Daily Fluid Rates
[Body weight (kg) × percent dehydration (decimal)] × 1000 = mL deficit
1. Maintenance 2. Fluid deficit – as assessed using hydration parameters
Calculating Daily Fluid Rates
1. Maintenance 2. Fluid deficit 3. Ongoing losses – estimation of volume continuing to be lost
http://www.summit107.com/news/east-kootenay-news/warning-of-potentially-fatal-canine-parvovirus-in-the-elk-valley/ https://www.medvetforpets.com/management-of-feline-lower-urinary-tract-disorder-flutd/
Calculating Daily Fluid Rates
1. Maintenance 2. Fluid deficit 3. Ongoing losses – estimation of volume continuing to be lost
(mL per hour ×24 hours)=mL of daily ongoing losses
Calculating Daily Fluid RatesMaintenance
Deficit [Body weight (kg) x percent dehydration (decimal)] x 1000
Ongoing Losses mL/day
volume (mL) to be administered over the next 24 hours
Hank, 4 YO CM German Shepherd Presenting for vomiting x 3 days -44 kg -5% dehydrated, to be corrected over 12 hours -estimated to be vomiting ~30 mL/hr
Maintenance = 1196 mL/day
Deficit Ongoing Losses
= 4116 mL
Hank
Maintenance = 1196 mL/day
Deficit = over 12 hours Ongoing Losses =
Hank
Maintenance = 1196 mL/day
Deficit = over 12 hours Ongoing Losses =
1196 mL + 720 mL = 1916 mL/24 hours = 80 mL/hr
2200 mL ÷ 12 hrs = 183 mL/hr
80 mL + 183 mL = 263 mL/hr for first 12 hours, then 80 mL/hour for next 12 hours
Egg Roll, 4 YO CM American Shorthair 2 days post-urethral obstruction, urinary catheter in place -urine output is measured every 4 hours -recent urine output measurement was 32 mL more than he received in IV fluids over those 4 hours
Maintenance = 234 mL/day
Deficit Ongoing Losses
32 mL/4 hours
http://www.vetstreet.com/cats/american-shorthair
Egg Roll -urine output is measured every 4 hours -most recent urine output measurement was 32 mL more than he received in IV fluids
Maintenance = 234 mL/day
Deficit Ongoing Losses
32 mL over 4 hours
http://www.vetstreet.com/cats/american-shorthair
Egg Roll
Maintenance = 234 mL/day
Deficit Ongoing Losses
32 mL over 4 hours
http://www.vetstreet.com/cats/american-shorthair
234 mL ÷ 24 hours = 9.8 mL/hr
32 mL ÷ 4 hours = 8 mL/hr
9.8 mL + 8 mL = 17.8 mL/hr for 4 hrs
Egg Roll http://www.vetstreet.com/cats/american-shorthair
You do not have an IV fluid pump available, but have a 10 drops/mL drip set to use.
What will your drip rate be for Egg Roll?
17.8 mL/hr ≈ 18 mL/hr
Egg Roll http://www.vetstreet.com/cats/american-shorthair
You do not have an IV fluid pump available, but have a 10 drops/mL drip set to use.
What will your drip rate be for Egg Roll? 17.8 mL/hr ≈ 18 mL/hr
Egg Roll http://www.vetstreet.com/cats/american-shorthair
You do not have an IV fluid pump available, but have a 10 drops/mL drip set to use.
What will your drip rate be for Egg Roll? 17.8 mL/hr ≈ 18 mL/hr
Egg Roll http://www.vetstreet.com/cats/american-shorthair
You do not have an IV fluid pump available, but have a 10 drops/mL drip set to use.
What will your drip rate be for Egg Roll?
17.8 mL/hr ≈ 18 mL/hr
Dextrose Supplementation! Commonly administered at
concentrations of 2.5-7.5% ! Concentrations >5% should be delivered
via a central line ! High osmolarity can cause phlebitis
https://www.bemedsupply.com/Dextrose-Water-5-Intravenous-IV-Solution-100ml-p/1-178433.htm https://www.pbsanimalhealth.com/products/dextrose-50-percent-iv-solution
Dextrose Supplementation
Calculation
! concentration you want ! volume you want
! concentration you have ! volume to add
Need to Know: 1. Concentration of dextrose solution 2. Concentration desired 3. Total volume desired
C1×V1 = C2 × V2
Dextrose Supplementation
CalculationNeed to Know: 1. Concentration of dextrose solution 2. Concentration desired 3. Total volume desired
C2 C2
Dextrose Supplementation
Calculation! concentration you want
! volume you want
! concentration you have ! volume to add
Conc. want Conc. have × vol. want = vol. to add
“The concentration you want over the concentration you have, times the volume you want, equals the volume to add.”
You want to add dextrose to your patient’s fluid bag to create a 5% solution. The bag contains 450 mL and
your dextrose solution is 50%. How much do you add?
“The concentration you want over the concentration you have, times the volume you want, equals the volume to add.”
Need to Know: 1. Concentration of dextrose
solution 2. Concentration desired 3. Total volume desired
50%
5% 450 mL
You want to add dextrose to your patient’s fluid bag to create a 5% solution. The bag contains 450 mL and
your dextrose solution is 50%. How much do you add?
“The concentration you want over the concentration you have, times the volume you want, equals the volume to add.”
( 550)× 450 mL= 45 mL
Constant-Rate Infusion
Also known as a CRI
• mg/kg/day • mg/kg/hr • mcg/kg/hr • mcg/kg/min
https://www.unitedadlabel.com/iv-medication-added-label-2-1-2-x-2-1-2 https://m.smiths-medical.com/products/infusion/syringe-infusion/syringe-infusion-pumps/medfusion-3500-syringe-pump https://careforde.com/monet-medical-smiths-medical-medfusion-2001-syringe-pump-reconditioned-2001r3-syringe-pump-3-year-warranty-ea/
http://www.realclear.com/animals/2015/01/21/cranky_critters_who_havent_had_their_morning_coffee_10563.html https://thecatsite.com/ams/why-does-my-cats-mouth-hang-open.33866/
A Concept to Remember
The volume you are administering will depend on two things: 1. Concentration 2. Rate
CRI Calculations
! Used for medications like metoclopramide inj.
Formula: Weight (kg) __ mg kg/day
OR
• mg/kg/day
• mg/kg/hr • mcg/kg/hr • mcg/kg/min
= __ mg/day
CRI Calculations
! Used for medications like metoclopramide inj.
Formula: Weight (kg) __ mg 1 mL kg/day __ mg
OR
• mg/kg/day
• mg/kg/hr • mcg/kg/hr • mcg/kg/min
= __ mL/day
Example
! Petey, 7 kg Rat terrier, vomiting, needs 2 mg/kg/day metoclopramide inj., concentration is 5 mg/mL
7 kg 2 mg 1 mL kg/day 5 mg = 2.8 mL/day
https://www.mooremedical.com/index.cfm?/Metoclopramide-Injection/&PG=CTL&CS=HOM&FN=ProductDetail&PID=12139&spx=1 https://www.dogster.com/dogbreed/rat-terrier
One Step Further…
! Petey, 7 kg Rat terrier, needs 2 mg/kg/day metoclopramide inj., concentration is 5 mg/mL, to be added to 1 L LRS and delivered at a rate of 22 mL/hr
! How many mL of metoclopramide needs to be added to the bag?
7 kg 2 mg 1 mL 1 day kg/day 5 mg 24 hrs = 0.12 mL/hr
https://www.mooremedical.com/index.cfm?/Metoclopramide-Injection/&PG=CTL&CS=HOM&FN=ProductDetail&PID=12139&spx=1 https://www.dogster.com/dogbreed/rat-terrier
One Step Further
! Petey, 7 kg Rat terrier, needs 2 mg/kg/day metoclopramide inj., concentration is 5 mg/mL, to be added to 1 L LRS and delivered at a rate of 22 mL/hr
! How many mL of metoclopramide needs to be added to the bag?
0.12 mL/hr
https://www.mooremedical.com/index.cfm?/Metoclopramide-Injection/&PG=CTL&CS=HOM&FN=ProductDetail&PID=12139&spx=1 https://www.dogster.com/dogbreed/rat-terrier
One Step Further…
! Petey, 7 kg Rat terrier, needs 2 mg/kg/day metoclopramide inj., concentration is 5 mg/mL, to be added to 1 L LRS and delivered at a rate of 22 mL/hr
! How many mL of metoclopramide needs to be added to the bag?
https://www.mooremedical.com/index.cfm?/Metoclopramide-Injection/&PG=CTL&CS=HOM&FN=ProductDetail&PID=12139&spx=1 https://www.dogster.com/dogbreed/rat-terrier
(1000 mL22mL/hr )=45.45 hrs/bag
One Step Further…
! Petey, 7 kg Rat terrier, needs 2 mg/kg/day metoclopramide inj., concentration is 5 mg/mL, to be added to 1 L LRS and delivered at a rate of 22 mL/hr
! How many mL of metoclopramide needs to be added to the bag?
7 kg 2 mg 1 mL 1 day 45.5 hrs kg/day 5 mg 24 hrs bag = 5.3 mL/bag
https://www.mooremedical.com/index.cfm?/Metoclopramide-Injection/&PG=CTL&CS=HOM&FN=ProductDetail&PID=12139&spx=1 https://www.dogster.com/dogbreed/rat-terrier
CRI Calculations ! Used for medications like diazepam, midazolam,
furosemide
Formula: Weight (kg) __ mg 1 mL kg/hr __ mg
• mg/kg/day
• mg/kg/hr • mcg/kg/hr • mcg/kg/min
= __ mL/hr
Example
! June Bug, 16 kg mixed breed canine, uncontrolled status epilepticus, needs 0.5 mg/kg/hr diazepam inj., available concentration is 5 mg/mL
https://www.petcha.com/about-the-mixed-dog-breed/ https://www.acesurgical.com/diazepam-5mg-ml-10ml-mdv-injection.html
Example
! June Bug, 16 kg mixed breed canine, uncontrolled status epilepticus, needs 0.5 mg/kg/hr diazepam inj., available concentration is 5 mg/mL
16 kg 0.5 mg 1 mL kg/hr 5 mg = 1.6 mL/hr
https://www.petcha.com/about-the-mixed-dog-breed/ https://www.acesurgical.com/diazepam-5mg-ml-10ml-mdv-injection.html
CRI Calculations• mg/kg/day • mg/kg/hr
• mcg/kg/hr • mcg/kg/min
! Used for medications like fentanyl
Formula: Weight (kg) __ mcg kg/hr = __ mcg/hr
https://www.askideas.com/20-very-funny-thumb-pictures-and-images/
CRI Calculations• mg/kg/day • mg/kg/hr
• mcg/kg/hr • mcg/kg/min
! Used for medications like fentanyl
! Formula: Weight (kg) __ mcg 1 mg kg/hr 1000 mcg = __ mg/hr
https://www.trendhunter.com/trends/cat-photography
CRI Calculations• mg/kg/day • mg/kg/hr
• mcg/kg/hr • mcg/kg/min
! Used for medications like fentanyl
! Formula: Weight (kg) __ mcg 1 mg 1 mL kg/hr 1000 mcg __ mg = __ mL/hr
Example
! Mater, 48 kg Great Dane, post-operative limb amputation, needs 4 mcg/kg/hr fentanyl inj., concentration is 0.05 mg/mL
https://www.buyemp.com/product/fentanyl-citrate-250-mcg-5-ml-injection-usp-cii https://www.google.com/search?q=great+dane+osteosarcoma&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjj8tDAu4zhAhUFzIMKHbNlAfQQ_AUIDigB&biw=1920&bih=937#imgrc=wcfyA_nT2OgT_M:
Example
! Mater, 48 kg Great Dane, post-operative limb amputation, needs 4 mcg/kg/hr fentanyl inj., concentration is 0.05 mg/mL
48 kg 4 mcg 1 mg kg/hr 1000 mcg = 0.192 mg/hr
https://www.buyemp.com/product/fentanyl-citrate-250-mcg-5-ml-injection-usp-cii https://www.google.com/search?q=great+dane+osteosarcoma&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjj8tDAu4zhAhUFzIMKHbNlAfQQ_AUIDigB&biw=1920&bih=937#imgrc=wcfyA_nT2OgT_M:
Example
! Mater, 48 kg Great Dane, post-operative limb amputation, needs 4 mcg/kg/hr fentanyl inj., concentration is 0.05 mg/mL
48 kg 4 mcg 1 mg 1 mL kg/hr 1000 mcg 0.05 mg = 3.8 mL/hr
https://www.buyemp.com/product/fentanyl-citrate-250-mcg-5-ml-injection-usp-cii https://www.google.com/search?q=great+dane+osteosarcoma&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjj8tDAu4zhAhUFzIMKHbNlAfQQ_AUIDigB&biw=1920&bih=937#imgrc=wcfyA_nT2OgT_M:
CRI Calculations• mg/kg/day • mg/kg/hr • mcg/kg/hr
• mcg/kg/min
! Used for medications like ketamine, lidocaine, norepinephrine, epinephrine, vasopressin
Formula: Weight (kg) __ mcg 1 mg 1 mL kg/min 1000 mcg __ mg = __ mL/min
CRI Calculations• mg/kg/day • mg/kg/hr • mcg/kg/hr
• mcg/kg/min
! Used for medications like ketamine, lidocaine, norepinephrine, epinephrine, vasopressin
Formula: Weight (kg) __ mcg 1 mg 1 mL kg/min 1000 mcg __ mg = __ mL/min
Example
! Maizy, 23 kg Labrador retriever, HBC with ventricular tachycardia, needs 40 mcg/kg/min lidocaine inj., concentration is 20 mg/mL
23 kg 40 mcg 1 mg kg/min 1000 mcg = 0.92 mg/min
https://www.thelabradorsite.com/dog-cone/ https://entirelypetspharmacy.com/lidocaine-injectable-100ml.html
Example
! Maizy, 23 kg Labrador retriever, HBC with ventricular tachycardia, needs 40 mcg/kg/min lidocaine inj., concentration is 20 mg/mL
23 kg 40 mcg 1 mg 1 mL kg/min 1000 mcg 20 mg = 0.05 mL/min
https://www.thelabradorsite.com/dog-cone/ https://entirelypetspharmacy.com/lidocaine-injectable-100ml.html
Questions?