# Equations

ephender's version from 2015-05-04 18:54

## Section 1

Question Answer
SensitivityTP/(TP+FN)
SpecificityTN/(TN+FP)
Positive Predictive ValueTP/(TP+FP)
Negative Predictive ValueTN/(FN+TN)
Odds Ration (case control)(A/C)/(B/D) | AD/BC
Relative Risk(a/(a+b))/(c/(c+d))
Attributable Risk(a/(a+b)) - (c/(c+d))
Number Needed to Treat1/ ARR
Number Needed to Harm1/ AR
Hardy Weinberg Equilibriump^2+ 2pq+q^2 = 1 | p + q = 1

## Section 2

Question Answer
Volume of Distributionamount of drug in body/ [Drug]plasma
Half Life(0.7XVd)/CL
Drug ClearanceRate of Elimination / [Drug]p = Vd X Ke (elimination constant)
Loading Dose First Aid(Cp X Vd )/ F |
Maintenance Dose First Aid(Cp X CL X t ) / F |
LD DIT Css X Vd
MD DITCss X CL

## Section 3

Question Answer
Cardiac OutputCO = Rate of O2 Consumption/ (O2 artery - O2 Vein) | CO = SV X HR
Mean Arterial PressureCO X TPR | 2/3 Diastolic + 1/3 Systolic
Stroke Vlume EDV- ESV
Ejection FractoinSV/EDV | (EDV-ESV)/EDV
ResistanceDriving Pressure (P)/ flow (Q) | (Viscosity (sn) X Length)/ pir^4

## Section 4

Question Answer
Net Filtration Pressure[(Pc - Pi) - (piC - piI)]
Renal ClearanceUxV/Px
GFRUinulin X V/Pinulin = Cinulin | Kf[Pgc-Pbs)-(piGC-piBS)]
Effective Renal Plasma FlorUpah X (V/Ppah)
Renal Blood Flow RBFRPF/1-Hct
Filtration FractionGFR/RPF

## Section 5

Question Answer
Henderson Hasselbalch (ph)6.1 + log [HCO3-]/ 0.03 Pco2
Winter Formulah PCO2 = 1.5 [HCO3-] + 8 +/- 2
Physiologic Dead SpaceVd = Vt X (Paco2-Peco2)/Paco2
Pulmonary Vascular Resistance(P pulm artery - PL atrium)/ CO
Alveolar Gas EqPAo2 = PIo2 - PCO2/R