USMLE Step 1 Equations

USMLE EquationsPharmacology Question Answer V<J Amount of drug In body / (Plasma drug concent rail on) CL (Rate of elimination of drug) / (Plasma drug concentration) Half Life (0.7 * Vd) / CL Loading dose (Cp x Vd) IF — Plasma drug concentration * Vd / bioavailability Maintenance dose Cp * CL / F pH pKa + Log (HC03/[0 03 Pco2) Km = [S] at ? [S] at SVmax Non-competitive inhibitor Decreases efficacy (Vmax) -> inc 1/Vmax Competitive inhibitor Decreases potency (increased Km)—> dec 1/Km Respiratory Question Answer Dead space Tidat volume " ([PaC02 - Pexp air C02]/PaC02| Alveolar ventilation (Tidal volume - Dead space)" Breaths/mln PA 0 2 = PA02 = ( Fi02 ' (760 - 47)) - (PaC02 / 0.8) — at room air (21% 02). PA02 = .21 ( 7 1 3 i - P a C 0 2 / 0 . 8 = 150 - PaC02 / 0.8 [1 instead of 0 8 if pt on 100% 02] = 150 - 1 25 - P a C 0 2 A-a gradient Alveolar 02 - arterial 02 = (at room air) 150mmHg - Pa02 (given) no mi a I A-a gradient 10mmHa or pt's age / 4 diffusion D - pressure x surface area x solubility / [membfane thickness x sqrt molec wtj Winter's formula (HC03PaC02) PaC02 = 1 5 x [HC03-] + 8 +/- 2 dec Pa02 with normal A-a gradient hypoventilation (inc PC02) . dec Fi02 (normal PC02) dec Pa02 with inc A-a gradient shunt (does not improve •:;ith inc 02) ; — V'Q mismatch or diffusion impairment (improve with inc 021 difference btwn V/Q mismatch and diffusion Impairment V/Q mismatch •• normal DLCO (diffusion): diffusion impairment dec DLCO (diffusion) causes of shunting (inc A-a gradient w/ no improvement on 100% 02) Atelectasis, pulmonary edema. Intra cardiac shunt (RightLeft) due to VSD; ASD: Vascular shunt within the lungs Cardiology Question Answer CO rate of 02 consumption/{Arterial 02-Venous 02) CO SV ' M R MAP CO * TPR = 2/3 diastolic + 1/3 systolic sv EDV - ESV EF SWEDV R 8n 11 (pi) r ft 4 R in series R = R1 + R2 R in parallel 1/R = 1/R1 + 1/R2 factors that inc viscosity polycythemia, high protein (MM), spherocytosis pulse pressure systolic - diastolic Biostats Question Answer Sensitivity TP / (TP+FN) = 1 - FN = TP / all real Ps Specificity TNI / (TN+FP) = 1 - FP = TN / all real Ns IPPV TP / (TP+FP) = TP / all apparent Ps INPV TN / (TN+FN) = TN / all apparent Ns Odds ratio OR = (a/b)/ (c/d) = ad / be — where a (risk factor + ds); b (risk factor - ds)r c (- risk factor + ds), d (- risk factor - ds) Relative risk |[a/(a+b)J / [c/(c+d)] — where a (risk factor + ds), lb (risk factor - ds), c (risk factor + ds) d (- risk factor - ds) = Incidence of exposed / incidence of unexposed Attributable risk |[a/(a+b)] - [c/(c+d)] — where a (risk factor + ds). lb (risk factor - ds). c (risk factor + ds). d (- risk factor - ds) = Incidence of exposed - incidence of unexposed Positive likelihood ratio Sens / [1 - Spec] = Sens / FP Negative likelihood ratio [1 - Sens) / Spec accuracy = ? accuracy = (TP+TN) / (TP+TN+FP+FN) = all accurates / total IH a rdy-Weinberg equil p*2 + 2pq + q*2 = 1 p + q = 1 confidence interval CI = mean +/- 2'slgma »> 95% CI type I error = ? b / (b+d) type II error = ? c / (a+e) s FN / Spec Renal GFR Uinulin / PinuJin * V= Cinulin GFR Kf[Pgc-Pbs) - (ONCgc-ONCbs)] RPF Upah / Ppah * V = Cpah RBF RPF/(1-Hct) FF GFFWRPF Documents Similar To USMLE Step 1 EquationsSkip carouselcarousel previouscarousel nextPathoma ChecklistAntimicrobialsMnemonics for USMLE Step 1Khan USMLE Pearls MicroSketchymicro Flashcards 2016 Share (1)Immunology high yield for STEP 1Pharmacology usmle step 1500 High Yield Nuggets Step 1Step 1 UworldList of Genetic Diseases HIGH YIELD USMLE STEP 1UWORLD Notes by Subject (Main Division) [Usmle Grassroots]UWorld NotesBiochemistry Metabolic Pathways & PathologiesPharm MnemonicsRenal CastsDIT High Yield Questions140033970 Microbiology USMLE Step 1 High Yield ImagesBehavioural Science notes usmleUSMLE Questions SummarizedKhan Usmle Pearls GitPathoma Notes Ch 1-3Pathoma LectureSketchy Micro CardsUSMLE Platinum Notes Step 1, Second EditionUSMLE PathognomicsStep 1 DrugsMajor Pharm ReviewUSMLE Step 1 Radiology Buzzwords - USMLE Forums246173104 Microbiology Step 1 Weird Exceptions and DetailSketchy Pharm PDF No PicturesBest Books About Medical SpecialtiesNURSING: The Ultimate Study Guideby Singh, Nadia BSN, RN, Singh BSN, RN, Nadia, and Nadia SinghThe Obesity Code: Unlocking the Secrets of Weight Lossby Jason Fung and Timothy NoakesDermatology Made Easyby Amanda OakleyClinical Microbiologyby Laposata, Michael MD; Stratton, Charles MD and Charles W. 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