Chemistry Flex Bench Flashcards

1
Q

contribute most to serum osmo

A

Na
Glucose
Urea

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2
Q

purpose of osmo

A

kidney’s concentration ability

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3
Q

typical causes for ↑ osmo

A

dehydration
kidney issues

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4
Q

osmo equation

A

1.86(Na) + (glu/18) + (BUN/2.8) + 9

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5
Q

osmo normal ranges

A

serum – 275-300 mOsm/kg
urine – 50-1200 mOsm/kg

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6
Q

osmo gap equation

A

measured osmo - calculated osmo
normal <10

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7
Q

causes of ↑ osmo gap and ↑ anion gap

A
  • PO4, SO4 (renal failure)
  • acetone, BHOB (DKA)
  • alcohol
  • lactate (tissue hypoxia)
  • ethylene glycol (antifreeze)
  • ANION gap – salicylate (aspirin OD)
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8
Q

anion gap (no K) equation and RR

A

Na - Cl + tCO2

RR: 7-16 mEq/L
RR with K: 10-20 mEq/L

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9
Q

excess anions/acids

A

↑ anion gap

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10
Q

sample size for osmo (in pipette)

A

20 μL

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11
Q

the osmo sample must be…
(size)

A

slightly longer than it is wide
no convex meniscus

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12
Q

osmo procedure for pts

A

run in duplicate
must be within 2 mOsm

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13
Q

1000 mOsm/kg depresses FP by…

A

-1.86° C

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14
Q

steps of FP osmometer

A
  1. fast cool
  2. reaches 0° – slow cool
  3. mechanical pulse freezes sample
  4. heat of fusion – asymptotically warms sample to its freezing point – temp approaches equilibrium
  5. plateau – osmolality is read
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15
Q

automated multi-wavelength spectrophotometric method used on ABG instruments

A

co-oximetry

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16
Q

test method for co-oximetry

A

1 μL blood heated to 37° and sonically hemolyzed by vibrating the cuvette walls at 30 kHz

Beer’s law is used to measure components

fractions of total Hgb are given

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17
Q

↑ Hgb affinity for O2

A

↑ pH
↓ pCO2
↑ pO2
↓ 2,3-DPG
↓ temp

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18
Q

↓ Hgb affinity for O2

A

↓ pH
↑ pCO2
↓ pO2
↑ 2,3-DPG
↑ temp

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19
Q

corrected barometric pressure

A

BP value - 47 mmHg [VP of water] = corrected BP

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20
Q

calibrate BP for gas content

A

corrected BP(% gas) = mmHg

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21
Q

ABG sample requirements

A
  • tightly stoppered
  • balanced heparinized syringe
  • on ice (2 hr) – 30 min no ice
  • no bubbles
  • perform ASAP
22
Q

non-balanced heparin effects…

A

electrolytes, especially cCa2+

23
Q

lipid therapy affects…

A

OXI measurements (Beer’s law)

24
Q

opposite arrows vs same arrows on either side of HH equation

A

opposite – respiratory
same – metabolic

25
Q

calibration for electrode drift

A

one-point

26
Q

calibration for electrode slope changes

A

two-point

27
Q

HH equation for blood gases

A

pH = 6.1 + log[HCO3/(pCO2)(0.03)]

28
Q

pKa for blood gases

A

6.1

29
Q

normal pH, HCO3, and pCO2

A

pH – 7.35-7.45
HCO3 – 22-26 mEq/L
pCO2 – 35-45 mmHg

30
Q

alkalosis/acidosis with normal pH

A

fully compensated

31
Q

P/F ratio equation and ranges

A

pO2/% inspired O2 = P/F

mild resp distress – 200-300
moderate – 100-200
severe – <100

room air is 21% O2
indicates ARDS or resp failure

32
Q

—–% O2 saturation for a capillary specimen is acceptable

A

> 70

33
Q

as pH ↓, iCa —-, because…

A


decreasing pH causes less Ca to be protein-bound

34
Q

iCa sample

A

dark green (heparinized plasma) tube with no gel

on ice (4hr) or not on ice (30 min)

half full

WB

35
Q

released with iCa to account for false changes

A

pH

36
Q

— iCa causes seizures, cardiac arrest

A

37
Q

— iCa causes nausea, constipation, kidney failure

A

38
Q

if osmo gap is >25…

A

suspect ingestion of substance

39
Q

high osmo gap with HAGMA

high anion gap metabolic acidosis

A

MEELK
- methanol
- ethylene glycol
- ethanol
- lactic acidosis
- ketoacidosis

40
Q

high osmo gap without HAGMA

high anion gap metabolic acidosis

A
  • isopropyl alcohol
  • mannitol
  • sorbitol
  • glycine
  • maltose

glycine, sorbitol, mannitol used for transurethral resection of prostate

41
Q

hyponatremia + euvolemia

A
  • SIADH
  • adrenal insufficiency
  • hypothyroidism
42
Q

hyponatremia + hypovolemia

A
  • diuretics
  • osmotic diuresis
  • vomiting
  • diarrhea
43
Q

hyponatremia + hypervolemia

A
  • kidney failure
  • cardiac arrest
  • cirrhosis
  • nephrotic syndrome
44
Q

↓ serum osmo
↓ serum Na
↑ urine output
↓ urine osmo

A

water overload

45
Q

↑ serum osmo
↑ serum Na
↑ urine output
↓ urine osmo

A

DI

46
Q

↓ serum osmo
↓ serum Na
↓ urine output
↑ urine osmo

A

SIADH

47
Q

causes of water overload

A

psychogenic/primary polydipsia

  • hypothalamic disease
  • drugs
  • altered mental status/psychiatric disease
48
Q

polyuria + polydipsia
>2.5 L/day urine output
crave water/ice
extreme fatigue, muscle weakness

A

DI

49
Q

2 types of DI

A

central – failure of pituitary to secrete normal ADH
nephrogenic – renal resistance to action of ADH

50
Q

fluid overload/weight gain
low urine output with high SG

A

SIADH

51
Q

causes of SIADH

A
  • malignant production of vasopressin
  • diseases of CNS
  • pulmonary disorders
  • side effects of drugs