Calculations

How to set up alligation problems?

Define osmolarity and equation for it

Osmolarity - measure of concentration that describes the total number of particles in one liter solution

Some compounds dissociate (break up) into multiple particles when dissolved in water

How to determine E value?

• When 2 solutions have same osmolarity (concentration)- they are isotonic

• Sodium chloride equivalent values (E values) represent how much the drug contributes to tonicity of a soluton compared to sodium chloride

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1 tsp = ___mL

t tbsp = ___mL

1 fluid oz = ___mL

1 cup =___oz

1 pint = ___oz

1 quart =___pints

1 gallon = ___quarts

1 tsp = 5 mL

t tbsp = 15 mL

1 fluid oz = 30 mL (29.57 mL)

1 cup = 8 oz

1 pint = 16 oz

1 quart = 2 pints

1 gallon = 4 quarts

1 kg = ? lbs

1 lb = ? oz = ? g

1 oz = ? g

1 grain = ? mg

1 kg = 2.2. lbs

1 lb = 16 oz = 454 g

1 oz = 28.4 g

1 grain = 65 mg

mol = ?

mmol = ?

mol = g / MW

mmol = mg / MW

mmol = mEq / valence

How to expression 660 parts per million as percentage?

% = ppm / 10,000

What are the common causes of anion gap for metabolic acidosis?

Cyanide

Uremia

Toluene

Ethanol

Diabetic ketoacidosis

Isoniazid

Methanol

Propylene glycol

Lactic acidosis

Ethylene glycol

Salicylates

Anion gap: AG > 12 mEq / L

• Na - Cl - HCO3-

pH < 7.35

HCO₂ < 22 mEq / L

What are some limitations of Cockcroft Gault Equation?

Doesn’t apply to ppl with

1) End stage renal disease

2) Rapidly fluctuating renal filtration

3) Reduced muscle mass (young children, pts missing limbs, malnourished)

4) Select dietary preferences

Measuring cystatin C is more accurate

How to calculate absolute neutrophil count?

ANC = Total WBC x [(%segs + %bands) / 100]

• Neutropenia < 1000

• Severe neutropenia < 500

• Profound neutropenia <100

Calories from parenteral nutrition components

How to find grams of nitrogen given grams of protein?

Grams of protein / 6.25 = grams of nitrogen

How to find glucose infusion rate (GIR) in mg/kg/min?

GIR = [(mg of dextrose} / (weight (kg)) x time (min)]

Arterial blood gases
Define metabaolic acidosis, respiratory acidosis

Define metabolic alkalosis, respiratory alkalosis

Henderson-Hasselbach equation

How to find specific gravity?

Define perecentage strength