Equations Flashcards

1
Q

Calculate filtration fraction

A

FF = GFR/RPF
RPF (Renal plasma flow) = RBF *(1-hct)

Note: GFR can be esp by inulin or Cr clearance
RPF can be estimated by PAH clearance
FF = Inulin clearance/PAH clearance

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2
Q

MAP = CO X PVR

eg solve for PVR if MAP inc from 95-130mmHg and CO doubled

A

PVR = MAP/CO = 130%/200% = 65%

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3
Q

Calculating FeNa

A

Filtered load = GFR x plasma Na

FeNA = Na excretion rate/filtered load

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4
Q

Calculate maintenance dose

A
MD = (steady state plasma level x clearance)/bioavailability
Clearance = clearance x body wt
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5
Q

Calculate GFR

A

GFR = (urine cr conc x urine flow rate)/plasma cr conc

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6
Q

Calculate FeH20

A

FeH20 = urine flow rate/GFR

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7
Q

Inulin clearance provides an estimate of what?

A

GFR

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8
Q

Calculate Renal blood flow given PAH

A

RBF = PAH clearance/ (1-hct)
RBF = (renal artery pressure - renal v pressure)/renal vascular resistance
Note: RBF is not the same as renal plasma flow

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9
Q

Calculate cardiac output

A
  1. CO = SV x HR

2. CO = Rate of O2 consumption/arteriovenous O2 content difference

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10
Q

Calculate volume distribution (L)

A

amount of drug given(mg)/plasma conc of drug (mg/L)

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11
Q

Relative risk formula

A

RR = [a/(a+b)] / [c/(c+d)]

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12
Q

Odds ratio formula

A

OR = ad/bc

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13
Q

Attributable risk percent in the exposed

eg RR = 5. 95% CI (2.9-7.1) calc percent of disease in patient attributed to exposure

A

ARR = 100 x [(risk in exposed - risk in unexposed)/risk exposed]
ARR = 100 x [(RR-1)/RR]
= 100 x [(5-1)/5)] = 80%

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14
Q
minute ventilation (L/min)
Alveolar ventilation (L/Min)
A
MV = TV (liters) x RR (breaths/min)
AV = (TV-dead space vol) x RR
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