Perioperative Fluid Therapy (Exam IV) Flashcards

1
Q

What is the formula for osmotic pressure?

A

P = (NRT) / V

P = pressure
N = # of molecules
R = constant
T= temp
V= volume

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2
Q

What is osmolarity?

A

particles / Liter of solvent

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3
Q

Higher osmolarity = _______ “pulling power”.

A

higher

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4
Q

What is osmolality?

A

particles / kg of solvent

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5
Q

What is normal serum osmolality?

A

280 - 290 mOsm

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6
Q

What three components produce oncotic pressure?

A
  1. Albumin
  2. Globulins
  3. Fibrinogen
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7
Q

What is the normal daily fluid intake?

A
  • 750 mL from solids
  • 350 mL from metabolism
  • 1400 mL liquid intake
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8
Q

What is the normal daily fluid output?

A
  • 1000 mL insensible loss
  • 100 mL GI loss
  • 0.5 - 1 mL/kg/hr UO
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9
Q

Urine output makes up approximately ___% of daily water loss.

A

60%

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10
Q

What sensors does the body have for fluid balance?

A
  • Hypothalamic osmoreceptors
  • Low pressure baroreceptors
  • High pressure baroreceptors
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11
Q

Where are high pressure baroreceptors located?
Low pressure baroreceptors?

A
  • High pressure → carotid sinus & aorta
  • Low pressure → large veins & RA
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12
Q

Where is renin release from?
What does it do?

A

Renin (released from juxtaglomerular cells) cleaves angiotensinogen to make angiotensin I.

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13
Q

How long does RBC replacement via erythpoiesis take?

A

4-8 weeks

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14
Q

Where is aldosterone released from?
What does it do?

A
  • Adrenal Cortex
  • Na⁺ and H₂O retention
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15
Q

What issues are associated with normal saline use?

A
  • Hemodilution
  • ↑ Cl⁻ and K⁺
  • Hyperchloremic metabolic acidosis
  • ↑AKI & RRT in critical care patients
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16
Q

How does lactated ringers osmolarity compare to that of NS?

A

LR osmolarity is lower than NS.

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17
Q

Why is lactate added to LR?

A

Buffering capacity

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18
Q

___ will excrete excess water faster than NS.

A

LR

Suppresses ADH secretion, allows for diuresis.

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19
Q

Lactate formation relies on what?

A

Hepatic metabolism

21
Q

What are the hemodilutionary effects of colloid administration?

A
  • ↓ plasma viscosity
  • ↓ RBC aggregation
22
Q

What fluid “class” can have adverse effects on the immune, coagulation, and renal systems?

A

Colloids

23
Q

What is Hetastarch?
What is it derived from?

A

Modified natural polymers of amylopectin derived potato or corn/maize.

24
Q

How much of intravascular volume expansion from hetastarch is still present in the system 90 minutes later?

A

70-80%

25
Q

What are side effects of hetastarch?

A
  • Coagulopathy
  • Renal dysfunction
26
Q

What is Dextran?

A

Highly branched polysaccharide

27
Q

What type of surgery is dextran useful for? Why?

A

Microvascular surgery due to inhibition of clotting cascade.

28
Q

What can dextran interfere with? (besides the clotting cascade)

A

Blood crossmatching due to coating of RBCs

29
Q

What are signs/symptoms of high intravascular volume?

A
  • ↑ capillary hydrostatic pressure
  • Edema
  • ↓ tissue O₂
  • Poor wound healing
  • Dysfunctional coagulation
30
Q

What are standards for NPO status?

A
31
Q

What is the classic formula for NPO/maintenance fluid replacement?

4-2-1 Rule

A

1st 10kg = 4 mL/kg/hr → 40mL/hr
2ⁿᵈ 10kg = 2 mL/kg/hr → 20mL/hr
Each 1kg over 20kg = 1mL/kg/hr

32
Q

What would the maintenance fluid rate (4-2-1 rule) be for a 110kg patient?

A

40 mL + 20 mL + (90 x 1mL/kg/hr) → 150 mL/hr

33
Q

What would the maintenance fluid rate be for a 18kg toddler?

A

1st 10kg → 40 mL
2ⁿᵈ 8kg → 16 mL

= 56 mL/hr

34
Q

How is fluid deficit replaced in a surgery?

A

½ calculated volume in 1st hour
¼ volume in 2ⁿᵈ hour
¼ volume in the 3rd hour

35
Q

How is fluid deficit calculated?

A

hours NPO x 4-2-1 maintenance rate

36
Q

How is hourly intraoperative volume replacement calculated?

A

Deficit + Maintenance + EBL

37
Q

How much blood do lap sponges hold?

A

100 mL

38
Q

How much blood do Raytech’s hold?

A

20 mL

39
Q

How much blood does a 4x4 hold?

A

10mL

40
Q

What would the replacement volume rate be for a surgical case that exhibits minimal (robotic, toe pin, cataract, etc.) evaporative/redistributive volume loss?

A

0-2 mL/kg/hr

41
Q

What would the replacement volume rate be for a surgical case that exhibits moderate evaporative/redistributive volume loss?

A

2-4 mL/kg/hr

42
Q

What would the replacement volume rate be for a surgical case that exhibits severe evaporative/redistributive volume loss?

A

4-8 mL/kg/hr

43
Q

How is the Parkland burn resuscitation formula calculated?

A

4 mL/kg/ %BSA burned

44
Q

How is the volume calculated via the parkland formula given?

A

½ in the 1st 8 hours
½ in the next 16 hours

45
Q

What are the general characteristics of goal directed therapy?

A
  • Volume administration based on hemodynamics
  • 1-3 mL/kg/hr crystalloid
  • 250cc fluid challenges for ↓SV
  • 1:1 colloids for blood loss
46
Q

What is normal SVV?

(PPV, SPV as well)

A

10 - 15 %

47
Q

What are the limits to assessment of volume via arterial waveform monitoring?

A

Low HR and/or RR
Irregular HR
Mechanical ventilation
Increased abdominal pressure
Thorax open
Spontaneous ventilation

48
Q

Colloid particles are separated via a centrifuge. T/F?

A

False. Colloid particles cannot be separated from crystalloid solution (via centrifuge or filtration).