Calculations Flashcards
KCL to Tablets conversion
KCL 10% = 20 mEq/15 mL
Calcium Salts elemental calcium conversion
Carbonate = 40% elemental calcium
Citrate = 20% elemental calcium
Aminophylline -> Théophylline
Multiply by 0.8 (ATM)
T -> A = Divide by 0.8
Statin conversions
Pitavastatin = 2mg
Rosuvastation = 5mg
Atorvastation = 10mg
Simvastatin = 20mg
Lovastatin = 40mg
Pravastatin = 40mg
Fluvastatin = 80mg
Metoprolol IV to PO conversion
1mg IV = 2.5mg PO
Loop diuretics conversion
Bumetanide 1mg = Torsemide 20mg = Furosemide 40mg
Furosemide IV to PO conversion
1mg IV = 2mg PO
Iron elemental conversions
Sulfate = 20% elemental
Insulin conversions
NPH BID -> Glargine QD = 80% of NPH dose
Toujeo -> other Glargine/Detemir = 80% of Toujeo dose
Levothyroxine IV to PO dosing
0.75mg IV = 1mg PO
Steroid conversions Methylprednisolone -> Prednisone/Prednisolone
4mg Methylpred = 5mg Pred
Lithium Conversions
5ml lithium citrate syrup = 300mg lithium carbonate = 8 mEq Li+ ion
Opioid conversions Morphine
10mg IV = 30mg Oral
Opioid conversion Hydromorphone
1.5mg IV = 7.5mg Oral
Opioid Conversion Oxycodone
20mg Oral = 7.5mg Hydromorphone oral = 30mg Morphine oral
Phenytoin total correction for albumin < 3.5
Total phenytoin measured / (0.2 X albumin) + 0.1
Ratio strength -> Percent Strength
X % strength = 100 / ratio strength
Percent Strength -> Ratio strength
Ratio strength = 100 / % Strength
Parts per million -> percent strength
Move decimal left 4 places
Percent strength -> Parts per million
Move decimal right 4 places
mOsmol/ L calculation
[(Wt of substance g/L) / ( MW g/mole)] X (# of particles) X 1,000
E formula
[(58.5)(i)] / [(MW of drug)(1.8)]
mols calculation
g / MW
mmols calculation
mg / MW
mEq formula
( mg X valence) / MW or mmols X valence
Fluid Requirement formula
Use when wt > 20 kg
1,500 mL + (20mL)(wt in kg - 20)
Total Energy expenditure (TEE) formula
BEE X activity factor X Stress factor
Activity factors
1.2 = non ambulatory / in bed
1.3 = ambulatory/ not in bed
Stress factors
Minor surgery = 1.2
Infection = 1.4
Major trauma = 1.5
Burns over 30% BSA = 1.5 - 2
BMI calculation
[weight (lbs) / height (in)^2] X 703
weight (kg) / height (m)^2
Calories from carbs/protein
4kcal / gram
Calories from fat
9 kcal / gram
Calories from dextrose monohydrate
3.4 kcal/gram
Calories from amino acid solutions
4 kcal/gram
Calories from ILE
ILE 10% = 1.1 kcal/mL
ILE 20% = 2 kcal/mL
ILE 30% = 3 kcal/mL
Grams of nitrogen from protein
Protein intake (g) / 6.25
Corrected calcium calculation
If albumin < 3.5
[Calcium (reported)] + [(4.0 - albumin) X 0.8]
ANC calculation
WBC X [(% seg + % bands)/100]
Temp conversion
C = (F - 32)/1.8
F = (C X 1.8) + 32
IBW males formula
50kg + (2.3 X in over 5ft)
IBW female formula
45.5 + (2.3 X in over 5ft)
CrCl formula
[( 140 - age) / (Scr X 72)] X wt (0.85 if female)
Adj BW formula
IBW + 0.4 (TBW - IBW)
How to reduce chances of precipitation from Calcium/Phosphate
Use calcium gluconate instead of calcium chloride
add phosphate first
Calcium/Phosphate not to exceed 45 mEq/L
Lower pH = less precipitation
Which drugs shouldn’t be crushed and given via feeding tubes
Enteric coated
Delayed or extended release
Sublingual or buccal forms
Hazardous drugs
General rule for preventing drug-nutrient interactions with tubes
hold 1hr before and 1-2hrs after admin of med
Drugs that can interact with tube feed nutrients
Warfarin
Quinolones/Tetracyclines
Levo
Cipro
Phenytoin
BMI classifications
< 18.5 = underweight
18.5 - 24.9 = normal weight
25 - 29.9 = over weight
> 30 = obese
When TBW < IBW which one do you use
TBW for all meds
When TBW = IBW or < 120% of IBW which one do you use
TBW for most meds
use IBW for Aminophylline/Theophylline/acyclovir/Levo
When obese (TBW > 120% IBW) which one do you use
IBW for Aminophylline/Theophylline/acyclovir/Levo
TBW for LMWHs,UFH, Vanco
AdjBW for AGs
Pt is dehydrated if….
BUN: SCr > 20:1
Which weight to use when calculating CrCl
TBW < IBW = use TBW
TBW = IBW = use IBW
TBW > IBW ( BMI < 25) = use IBW
TBW > IBW (BMI > 25) = use Adj BW
Arterial Blood Gas 3 Steps
- pH < 7.35 -> acidosis, pH > 7.35 -> alkalosis
- Respiratory CO2 -> < 35 = alkalosis, > 45 = acidosis
Metabolic HCO3 -> > 26 = alkalosis, < 22 = acidosis - Match up parts from Step 1 & 2 = answer
How to read ABG
pH/pCO2/pO2/HCO3/O2 sat
^ ^ ^
important ones (1,2,4)
Anion gap formula
Na - Cl - HCO3
Causes of gap acidosis
CUTE DIMPLES
Cyanide, uremia, toluene, ethanol
Diabetic ketoacidosis, isoniazide, methanol, propylene glycol, lactic acidosis, ethylene glycol, salicylates)
When is anion gap considered high?
> 12 = gap acidosis
If pH > pKa then
more acid ionized, more conjugated base un-ionized
if pH < pKa then…
more acid un-ionized, more conjugated base ionized
Weak acid formula
pH = pKa + Log (salt/acid)
Weak base formula
pH = pKa + log (Base/salt)
or
pH = (pKw - pKb) + log (Base/salt)
% ionization of weak acid
(100) / ( 1+ 10^[pKa - pH])
% ionization of weak base
(100) / ( 1+ 10^[pH- pKa])
ANC lvls
2,200 - 8,000 = normal
< 1,000 = Neutropenia
< 500 = Severe Neutropenia
< 100 = Profound Neutropenia
Calcium citrate to elemental calcium conversion
21%