Chapter 187 - colloid osmotic pressure and osmolality monitoring Flashcards

1
Q

goal COP to reduce the risk of oedema formation in dogs and cats?

A

15 mm Hg

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2
Q

which term is redundant?
colloid osmotic pressure
colloid oncotic pressure
oncotic pressure

A

colloid oncotic pressure

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3
Q

what is the percentage contribution of albumin (and associated cations) to COP?

A

60-70%

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4
Q

what is the percentage contribution of globulins to COP?

A

30-40%

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5
Q

state Starling’s principal

A

net rate of capillary filtration = the difference between capillary and interstitial hydrostatic pressure minus the osmotic reflection coefficient outside the difference between the plasma and interstitial oncotic pressure

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6
Q

which variable(s) in Starling’s principal can be manipulated clinically?

A

plasma oncotic pressure

capillary hydrostatic pressure

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7
Q

in the revised Starling’s principal, which variable is changed?

A

COP of the subglycocalyx space is used instead of the COP of the interstitium

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8
Q

to what level will the total solids (by refractometer) trend towards in patients receiving artificial colloids?

A

4-4.2mg/dL

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9
Q

published normal COP for canine and feline plasma?

A

dogs: 21-25mmHg
cats: 23-25mmHg

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10
Q

published normal COP for canine and feline whole blood?

A

dogs: 17.85-22.05mmHg
cats: 21-28.4mmHg

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11
Q

indications for COP measurement

A
  1. patients receiving artificial colloids
  2. patients with oedema
  3. patients treated with aggressive crystalloid therapy with with low serum albumin
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12
Q

3 strategies for treatment of low COP?

A

plasma
human/canine albumin solutions
artificial colloids

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13
Q

osmolarity v osmolality

A

osmolality: number of osmotically active particles/kg of solution
osmolarity: number of particles/L volume of solution

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14
Q

normal osmolality?

A

dogs: 290-310mOsm/kg
cats: 290-330mOsm/kg

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15
Q

formula for calculation of osmolality

A

2(Na+) + (BUN/2.8) + (glucose/18)

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16
Q

common causes of increased osmolality can be due to increases in effective and ineffective osmoles. name 7 effective osmoles

A

sodium, glucose, mannitol, ketoacids, lactic acids, phosphate & sulfates (ie- w/ renal failure), radiopaque contrast solutions

17
Q

common causes of increased osmolality can be due to increases in effective and ineffective osmoles. name 7 ineffective osmoles

A

BUN, ethylene glycol & metabolites, ethanol & methanol, acetylsalicylic acid, isopropyl alcohol

18
Q

most common cause of hypoosmolality?

A

hyponatremia

19
Q

most common 3 causes of hyperosmolality?

A

hypernatremia, DM, azotemia

20
Q

define osmolal gap

A

measured plasma osmolality - estimated plasma osmolality

21
Q

normal osmolal gap?

A

dogs: -5 - 2mOsm/kg
cats: -3 - 6mOsm/kg

22
Q

cut-off osmolal gap above which unmeasured solutes are present in large quantities?

A

10mOsm/kg

23
Q

calculation for effective osmolality or tonicity?

A

2 (Na+) + (glucose/18)

24
Q

difference between USG and urine osmolality

A

USG measures a ratio of the density of a substance compared to water (affected by the number of molecules and their molecular weight)
urine osmolality measures the number of molecules/kg of water

25
Q

name 4 indications for measurement of urine osmolality

A

differentiating sodium disorders
identifying SIADH
differentiating renal from pre-renal azotaemia
diagnosing diabetes insipidus