Disclaimer - All information contained in and produced by MDgrad, including MDgrad Quick Calc, is for educational purposes only. This information should not be used for the diagnosis or treatment of any illness or disease and is in no way intended to replace clinical judgment or guide individual patient care. See Full Disclaimer
Clinical Calculators
Alveolar- Arterial Gradient
(A-a gradient) 		PAO2 - PaO2 = A-a gradient
PAO2 = {(pATM-pH20) X FiO2} - pCO2/R
PaO2 = partial pressure of O2 on ABG
at sea level on room air (pATM - pH2O) X FiO2 = 150 , So PAO2 equation can be simplified to = 150 - pCO2/.8
A -a gradient Age Estimation = 2.5 + .21(age in years)		 R = Resp Quotient = 0.8
pATM sea level = 760
pH2O = 47 at 37 degrees C
FiO2 = .21 on room air
Absolute Neutrophil Count = WBC X (Polys + Bands)/100
Anion Gap- Urine = U[Na] + U[K] - U[Cl]
Anion Gap - Serum = [Na] - ([Cl] + [HCO3])
Body Surface Area = 0.007184 X (cm ^ 0.725) X (kg ^ 0.425)
Cardiac Index = Cardiac Output / BSA in m^2
Fick Cardiac Output = VO2 / (10 X Hb X 1.34 (SaO2 - SvO2))

VO2 = Estimated O2 consumption based on nomogram for height, weight, age and sex.
SaO2 = Arterial O2 sat from ABG
SvO2 = Mixed Venous O2 sat from PA catheter (if no shunt present)
Corrected QTc

= QT / sqrt(RR interval)

LDL Cholesterol = Total chol - HDL - (Triglycerides / 5)
for Triglycerides less than 400
Cr. Clearance (Cockcroft-Gault) ml/min

= (140 - age)(lean wt in kg) / (72 X serum [Cr] )
multiply by .85 in women

Cr. Clearance (Measured by 24 hour urine collection) in ml/min

= {U[Cr] X (cc urine vol)} / (Serum[Cr] X 1440 minutes)

Fractional Excretion of Sodium = Urine Na X Serum Cr./ Serum Na X Urine Cr. X 100
Free H20 Deficit = (0.6 X kg X (Serum[Na])/140) - 1
Henderson-Hasselbach pH = 6.1 + Log ( [HCO3] / (0.03 X pCO2))
Rate Pressure Product or Double Product = HR X SBP
Osmol Gap Calculated Serum Osmolarity - Measured Serum Osmolarity
Reticulocyte percentage = Reticulocyte count / RBC count
Corrected Reticulocyte Count (absolute reticulocyte count) = (Reticulocyte percentage) X (Actual Hct / 45)
Reticulocyte Production Index = (Reticulocyte percentage) X (Actual Hct / 45) / Maturation index
Serum Ca (corrected) = (Normal [Alb] - Serum[Alb] ) X 0.8 + [Ca]
Serum Na (corrected) = [Na] + ([Gluc in mg/dl] - 100) X .016
Serum Osmolority (Calculated) = 2[Na] + Glucose/18 + Bun/2.8 + [ethanol]/4.6
Sensitivity

a / a + c

a = true pos,   b = false pos
c = false neg , d = true neg
Specificity
d/ b + d
Positive Predictive Value
a / a + b
Neg Predictive Val
d / c + d
Conversions  
Fahrenheit to Celcius C = 5(F-32)/9
Celcius to Fahrenheit F = C X 9/5 + 32
inches to cm 1 cm = 0.39 inches
cm to inches Inch = 2.54 cm
kg to lbs 1 lb = 0.454 kg
lbs to kg 1 kg = 2.204 lbs
1 Liter = 1.06 qts = 33.81 oz