Calculations Flashcards
1 lb = _______ oz = _________ g (weight conversion)
16 oz; 454g
1 gal = ______ qt = _______ pints
4 quarts; 8 pints
1 quart = __________ pints
2 pints
1 tbsp = ________ tsp = ________mL
3 tsp; 15 mL
1 tsp = ________mL
5 mL
1 cup = ______ oz = ________mL
8 oz; 236.56 mL (approximately: 240mL)
1 pint = ______ cups = ________ oz = ______mL
cups; 16 oz; 473mL (approximately: 480mL
1 quart = ________ pints = ______ oz = ______mL
2 pints; 32 oz; 946mL (approximately: 950mL)
1 gallon = ______ quarts = _______ oz = _______mL
4 quarts; 128 oz; 3,785mL (approximately: 3,840mL)
1 gr = ________mg
64.8 mg (approximately 65mg)
1 oz = __________ g = _____mL
28.35 g; 30mL
1 kg = _________ lb = ________g
2.2 lb; 1000g
1 inch = ________ cm
2.54 cm
1 meter = _______ cm
100 cm
1 L = _______mL
1000 mL
1 mg = _________mcg
1000 mcg
1 cc = ______mL
1 mL
1 g = _________mg
1000mg
Insulin U-100 = _________ IU/mL
100 international units/mL
Opthalamic and otic drops: 1mL = _________gtts unless stated otherwise
20 gtts
Degrees Celcius = _________
(Degrees F - 32) x 5/9
Degrees Fahrenheit= ____________
(Degrees C x 9/5) + 32
Time to Burn (TTB) with sunscreen in min = ___________________
SPF x TTB (without sunscreen)
W/V %
Weight of solute (g) / volume of solution (mL) x 100%
V/V %
Volume of solute (mL) / volume of solution (mL) x 100%
W/W %
Weight of solute (g) / weight of solution (g) x 100%
Mostellar Formula (BSA calculation)
BSA in m2 = square root [(ht in cm x weight kg) /3600]
OR
BSA in m2 = square root [(ht in in x weight in lb) / 3131]
Dilution Calculation
C1 x V1 = C2 x V2
C1 = initial concentration
V1 = initial volume
C2 = final concentration
V2 = final volume
Infusion Rates
Rate of infusion = volume of fluid / time of infusion
Ex. mL/min, mL/hr, gtts/mL
Ratios: how to determine 1 part of ____%
Proportions
Ex. what is 1 part of 35%?
35% / 100% = 1 part / X
Ratios: how many parts for each drug
Add total parts then proportion
Ex. drug A / drug B ratio = 3:5
-Total parts = 8
-Drug A = 3/8
-Drug B = 5/8
Alligations
Used to prepare a concentration of solution NOT commercially available
Higher % solution parts
Desired %
Lower % solution parts
- Determine total # of parts by adding together
-Take higher % - Desired % = total parts of lower %
-Take lower percent - Desired % = total parts of higher %
-Add lower and higher parts together = total - Set up proportion using parts of each concentration
-Ex. Amount of higher solution % = parts higher solution / total parts x total volume needed
Parts Per Million
PPM = grams of solute / grams of solution x 1,000,000
Solution = solute + solvent
Ex. 50 PPM = 50 parts / 1,000,000
Short-cut:
-PPM to percentage: move decimal LEFT four places
-Percentage to PPM: move decimal RIGHT four places
Specific Gravity
Specific gravity = (weight of substance / weight of equal volume of water) = (density of substance / density of standard) = ____g/mL
Density of water = 1000kg/m^3
Weight = density x volume
Normal Saline (NS) = _________%
0.9% (w/v)
1/2 NS = _________%
0.45% (w/v)
D5W = __________%
5% (w/v) dextrose in water
D10W = ___________
10% (w/v) dextrose in water
D5NS = ________% and _________% in water
5% dextrose and 0.9% NaCl in water
_____ g NaCl in 500mL of 0.9% NaCl
4.5 g
Conversion from theophylline to aminophylline and vice versa
Theophylline to Aminophylline: divide by 0.8
Aminophylline to theophylline: multiply by A (“ATM” = A to T multiply)
Metoprolol: IV to PO ratio
1: 2.5
Ex. 10mg IV metoprolol = 25mg PO metoprolol
Furosemide: IV to PO ratio
1:2
Ex. 20mg IV furosemide = 40mg PO furosemide
**OTHER loop diuretics are just 1:1 ratios
Ethacrynic acid ___mg = Furosemide ____mg = Torsemide ____mg = Bumetanide ____mg
Ethacrynic acid 50mg = Furosemide 40mg = Torsemide 20mg = Bumetanide 1mg
Levothyroxine: IV to PO ratio
0.75:1
Ex. 75mcg IV levothyroxine = 100mcg PO levothyroxine
Cortisone ____mg = Hydrocortisone ____mg = Prednisone ___mg = Prednisolone ____mg = Methylprednisolone _____mg = Triamcinolone ____mg = Dexamethasone _____mg = Betamethasone ____mg
Cortisone 25mg = Hydrocortisone 20mg = Prednisone 5mg = Prednisolone 5mg = Methylprednisolone 4mg = Triamcinolone 4mg = Dexamethasone 0.75mg = Betamethasone 0.6mg
Lithium citrate syrup 5mL = _______mg of lithium carbonate = ____mEq Li+
300mg; 8 mEq
Calcium carbonate = _______% elemental Ca++
40%
Calcium citrate = _______% elemental Ca++
21%
Calcium acetate = _______% elemental Ca++
35%
pH = _______________________
How to interpret pH and pKa
pKa + log [base/acid]
or
pKa + log [A-/HA]
or
pKa + log [salt/acid]
pH > pKa: more acid is ionzied
pH = pKa: equal amounts of ionized and un-inonized forms
pH < pKa: more of conguate base is ionized
Most drugs: WEAK ACIDS
% Ionization (weak acid) = ________________
100 / [1+10^(pka-pH)]
% Ionization (weak base) = _____________
100 / [1+10^(pH-pka)]
Anion Gap (AG) = _____________________
-What are typical levels?
-What is the corrected formula if albumin is out of range?
-Causes of anion gap (CUTE DIMPLES)?
AG = Na - (Cl + HCO3)
Normal levels: 8-16 (Considered high when >12)
Corrected AG = AG + [ 2.5 x (4-albumin)]
CUTE DIMPLES:
-C: Cyanide
-U: Uremeia
-T: Touline
-E: Ethanol (alcoholic ketoacidosis)
-D: Diabetic ketoacidosis
-I: Isonazid
-M: Methanol
-P: Propylene glycol
-L: Lactic acidosis
-E: Ethylene glycol
-S: Salicylates
Arterial Blood Gas (ABG):
1. pH > _________ = alkalosis
2. pH <_________ = acidosis
- In respiratory, a pCO2 <_____ indicates alkalosis, while a pCO2 > _______ indicates acidosis.
- In metabolic, a HCO3 >_____ indicates alkalosis, while a HCO3 <_______ indicates acidosis.
Acidosis: pH <7.35
Alkalosis: pH >7.45
Respiratory:
-Acidosis: pCO2 > 45
-Alkalosis: pCO2 <35
Metabolic:
-Acidosis: HCO3 <22
-Alkalosis: HCO3 > 26
Absolute Neutrophil Count (ANC) = _____________________________________________
WBC x (segmented neutrophils% + segmentedbands%) / 100
Osmolarity Gap = _________________________
-What are typical levels?
-When might osmolar gap be evaluated?
Osmolarity Gap = measured osmolarity - calculated osmolarity
Calculated osmolarity = 2(serum Na) + (glucose/18) + (BUN/2.3) + (ethanol/4.6)
Normal levels: around 10
Osmolar gap identifies unmeasured osmols to resolve underlying insults (ex. toxic alcohol ingestions)
Osmolarity (mOsmol/L) = ________________
[wt of substance (g/L) / MW (g/mole)] x # of particles x 1,000
Isotonicity (E) = _________________________
[58.5 x i] / [MW of drug x 1.8]
Moles (mols) = ___________________________
g / MW
Millimoles (mmols) = ____________________
mg / MW
Milliequivalents (mEq) = __________________
[mg x valence] / MW
or
mmols x valence
Measures an electrolyte’s chemical activity according to valence and their dissociation ability in liquid
KCl 10% = ___________________________________
20 mEq / 15mL
Corrected calcium = ________________
Corrected Ca++ = measured Ca + [0.8 x (4-albumin g/dL)
Corrected sodium = _____________________
Corrected Na+ = measured Na + (0.2 x triglyceride levels) OR
Corrected Na+ = measured Na + [1.6 x (measured glucose - 100) /100]
Water deficit = ___________________________
Water deficit = 0.6 x weight in kg x [(serum Na/140) -1]
Determining general fluid needs: when a person weighs >20kg, what is the general equation?
1,500mL + [20mL x (weight in kg - 20)]
Can be estimated by about 30-40 mL/kg/day
Ideal Body Weight (IBW)
Men = 50 + [2.3 x (every inch >60 inches)]
Women = 45.5 + [2.3 x (every inch >60 inches)]
**If someone is under 5 feet
Men = 50 + [2.3 x (every inch <60 inches)]
Women = 45.5 - [2.3 x (every inch <60 inches)]
Adjusted Body Weight (Adjusted BW)
Adjusted BW = IBW + [0.4 x (TBW-IBW)]
**IBW = Ideal Body Weight
**TBW = Total Body Weight
Creatinine Clearance (Cockcroft-Gault)
CrCl = (140 - age) / [(72 x SCr) x weight in kg)] x 0.85 if female
**Use adjusted BW if actual body weight is >130% IBW
A BUN/SCr ratio > ____:____ suggests dehydration.
> 20:1
Body Mass Index (BMI)
BMI = (weight in kg) / (height in m2) OR
BMI = (weight in lb / height in in2) x 703
BMI Readings:
-Less than 18.5: Underweight
-18.5-24.9: Normal weight
-25-29.9: Overweight
-30-34.9: Obese
-Over 35: Morbidly obese
For the following drugs/scenarios, determine which type of weight should be used for the calculation (TBW, IBW, AdjustedBW):
1. Underweight individuals in all drugs
- Normal weight or obese in most drugs
- Acyclovir, Aminophylline, Levothyroxine, Theophylline (normal weight or obese)
- Aminogylcosides (obese)
- TBW
- TBW
- IBW
- AdjustedBW
Protein and Carbs = _____kcal/g
4
Dextrose = _________kcal/g
3.4
Fat = __________kcal/g
9
Intravenous Lipid Emulsions (ILE):
1. ILE 10% = _______kcal/mL
2. ILE 20% = ______kcal/mL
3. ILE 30% = ______kcal/mL
10%: 1.1 kcal/mL
20%: 2 kcal/mL
30%: 3 kcal/mL
Total Energy Expenditure (TEE) = ______________________________________________
BEE (Basal Energy Expenditure) x activity factor x stress
Nitrogen in g = ____________________________
protein intake (g) / 6.25
Bioavailability (F) = ________________________
F = 100% x [(PO AUC / IV AUC) x (IV dose / PO dose)]
Volume of Distribution (Vd) = ___________
Cl / K
or
Amount of drug in body / concentration of drug in plasma
Half-life (T1/2) = _______________________
0.693 / k
Clearance (CL) = __________________________
Cl = F x dose / AUC
or
Cl = K x Vd
Predicting Drug Concentrations:
C2 = ___________________________________
K = _______________________________________
C2 = C1 x e^-kt
K = [ln (C1/C2)] / t
Loading Dose (LD) = _____________________
[Desired concentration x Vd] / F
Corrected phenytoin (mcg/mL)= ___________________
Phenytoin measured/ [(albumin x0.2) + 0.1]
**For renal disease, change 0.2 to 0.1
Mean Arterial Pressure (MAP) = _____________________________________________
[2 x DBP + SBP] / 3
Friedewald Equation: LDL = _____________________________________________
TC - HDL - (TG / 5)
**do NOT use if TG > 400
Minimum Weighable Quantity (MWQ) Equation for compounding
MWQ = sensitivity replacement / acceptable rate error (usually 0.05)
Pack-year smoking hx = _________________
Cigarette packs/day x years smoked
Initiating basal-bolus insulin in T1DM
- Calculate total daily dose (TDD) of 0.5 units/kg/day using TBW
- Divide into 1/2 basal and 1/2 rapid-acting
- Split rapid acting among meals
Insulin-to-Carbohydrate Ratio: What rules are used for regular versus rapid-acting insulin?
Rule of 450: 450 / TDD of insulin = grams of carbohydrates covered by 1 unit of REGULAR insulin
Rule of 500: 500 / TDD of insulin = grams of carbohydrates covered by 1 unit of RAPID-acting insulin
Correction factors for regular and rapid-acting insulin
1,500 Rule: 1,500 / TDD of insulin = correction factor for 1 unit of REGULAR insulin
1,800 Rule: 1,800/ / TDD of insulin = correction factor for 1 unit of RAPID-acting insulin
Correction Dose for Insulin: [BG currently taken - target BG] / correction factor
General insulin conversion ratios
Typically 1:1
Exceptions:
-NPH dosed BID: converting to glargine, use 80% of NPH dose
-Toujeo (insulin glargine) to other forms of glargine or detemir: use 80% of Toujeo dose
Risk = ___________________________(Biostats)
of subjects in group with UNFAVORABLE event / total # of subjects
of subjects in group with UNFAVORABLE event / total # of subjects
Relative Risk (RR) = ________________________
Risk in TX group / Risk in control group
Relative Risk Reduction (RRR) = ____________________________________________
[% of risk in control group - % of risk in TX group] / % risk in control group
Absolute Risk Reduction = _______________
% risk in control group - % risk in TX group
Number Needed to Treat (NNT) or Number Needed to Harm (NNH) = __________________________________________
1 / ARR (Absolute Risk Reduction)
Odds Ratio = ____________________________
[Outcome present with exposure present x Outcome absent with exposure absent] / [Outcome absent with exposure present x Outcome present with exposure absent]
Hazard Ratio (HR) = _____________________
Hazard rate in TX group / Hazard rate in control group
Incremental Cost-Effectiveness Ratio
[C2 - C1] / [E2 -E1]
C = costs
E = effects
K, Na, and other monovalent ions: 1 mEq = ________mmol
1 mmol
Ca++ and other divalent ions: 1 mEq = ______ mmol
0.5 mmol