USMLE First Aid 2016 Equation Review – Flashcards
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Sensitivity
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=TP / (TP+FN)
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Specificity
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=TN / (TN+FN)
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PPV
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=TP/(TP+FP)
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NPV
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=TN/(FN+TN)
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Odds ratio (for case control studies)
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=AD/BC = (A/C)/(B/D)
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Relative Risk
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= [a/(a+b)]/[c/(c+d)]
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Attributable Risk
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=[a/(a+b)]-[c/(c+d)]
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Relative Risk Reduction
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RRR=1-RR
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Absolute Risk Reduction
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=[c/(c+d)]-[a/(a+B)]
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Number needed to treat
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=1/ARR
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Number needed to harm
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=1/AR
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Hardy-Weinberg equilibrium
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p^2+2pq+q^2=1 p+q=1
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Volume distribution
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=amount of drug in body/plasma concentration
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Half-life
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=0.693x(Vd/CL)
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Drug Clearance
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=Rate of elimination of drug/plasma drug concentration=Vd*Ke(elimination constant)
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Loading dose
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=[Cp*Vd]/F
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Maintenance dose
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=[Cp*Cl*tau]/F
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Cardiac Output
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=Rate of O2 consumption/[Arterial O2 content- Venous O2 content] =SV*HR
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Mean Arterial Pressure
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=CO*TPR =2/3*diastolic + 1/3* systolic
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Stroke Volume
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=EDV-ESV
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Ejection Fraction
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=SV/EDV=[EDV-ESV]/EDV
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Resistance
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=Driving Pressure (deltaP)/Flow (Q) =[8*viscosity*length]/[pi*r^4]
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Capillary fluid exchange (Jv)
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=Net fluid flow =Kf[(Pc=Pi) - (Permeability of capillary to protein)*(pi-c - pi-i)]
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Renal clearance (x)
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=U(x)*V/P
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Glomerular Filtration Rate
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=U(inulin) x V/P(inulin) =K(f)[(P(gc)-P(bs))-(pi(gc)-pi(bs))
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Effective renal plasma flow
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=U(pah)*(V/P(pah))
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Renal Blood Flow
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=RPF/(1-Hct)
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filtration Fraction
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=GFR/RPF
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Henderson-Hasselbalch equation for extracellular pH
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=6.1 + log [HCO3-]/0.03*Pco2
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Winters formula
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Pco2=1.5*[HCO3-]+8 (+-)2
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Physiologic dead space
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V(d)= V(t)*(Pa(co2)-Pe(co2))/Pa(co2)
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Pulmonary vascular resistance
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=[P(pulm artery)-P(L atrium)]/CO
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Alveolar gas equation
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=P(Io2)-[Pa(co2)/R]
