Stats/Equations Flashcards

1
Q

Qp:Qs

A

(Ao sat - SVC sat) / (PV sat - PA sat)

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2
Q

PVR (woods units)

A

(mean PA pressure - mean LAP) / Qp

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3
Q

Qs:QT or % shunt

measures VQ mismatch

A

(PV sat - PA sat) / (PV sat - SVC sat)

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4
Q

Hardy Weinberg equations

A

p + q = 1

p^2 + 2pq + q^2 = 1

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5
Q
  • As the prevalence increases, the PPV ______ and the NPV ______.
  • As the prevalence decreases, the PPV ______ and NPV ______.
A
  • As the prevalence increases, the PPV increases and the NPV decreases.
  • As the prevalence decreases, the PPV decreases and NPV increases.
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6
Q

Variables!

A

Qualitative variables (categorical)

    • nominal - no order, no magnitude (gender, blood type)
    • ordinal - has order but no set magnitude (ROP, NEC)

Quantitative variables (continuous)

    • interval - equal intervals but no meaningful zero (apgars, temperature)
    • ratio - equal intervals with meaningful zero (birthweight, residuals)
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7
Q

between case-control and cohort studies, when do you use RR and when OR?

A

Use OR with case-control and RR with cohort

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8
Q

How do you increase the power (decrease type II error) of a study?

A

think MASS:

  • increase magnitude of difference
  • increase alpha
  • increase sample size
  • decrease std deviation
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9
Q

What does changing the p value do to type I and type II errors?

A

Increasing p value increases chance of type I error (finding a difference when there isn’t one)
Increasing p value decreases the change of type II error (not finding a difference when there is one)

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10
Q

KBT?

A

every % of fetal hemoglobin = 50 mls lost

Eg: 3 fetal cells, 100 maternal cells. 3% = 150 mls lost

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11
Q

polycythemia exchange transfusion?

A

TBV (O-E/O)

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12
Q

If infant’s hct drops, how do you calculate EBL?

A

(change in hct/avg of hcts) x TBV

eg:
If hct went from 55 -> 45 in a 2 kg kid:
10/50 x 180 = 36 mls

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13
Q

what is the new hct after a volume of PRBC’s are transfused?

A

change in hct = (vol PRBC’s x hct PRBC’s)/TBV

eg, give 15 ml/kg of PRBC’s with a hct of 60 to a 2 kg kid:
30 x 60 / 180 = hct will increase by 10

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14
Q

If your TV decreases from 6 mls to 3 mls, how much can you expect your CO2 to increase by?

A

dead space always = 2mls
So TV actually decreased 4 mls to 1 ml

CO2 will go up 4x what it was prior

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15
Q

Which one is prevalence, which one is incidence:

  • 0.05%
  • 5 cases per 10,000 children per year
A
  • 0.05% = prevalence
  • 5 cases per 10,000 children per year = incidence

incidence includes cases plus the time “in” which it happens

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