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Anesthesia > Fluids > Flashcards

Fluids Flashcards

1
Q

Body weight at birth is comprised of what % of total body water? Then at adult?

A

75-80% then it decreases with age
60%

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2
Q

What is the fluid compartment 60:40:20 rule?

A

60% is total water in body
Intracellular space is 40% bw
Extracellular is 20% bw
- Interstitial is 15% bw
- Intravascualr/plasma water is 5% bw

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3
Q

What is osmolality?

A

number of particles in a solution (osmoles of
solute) per kg of solvent.

The plasma contains unbound particles, positively and
negatively charged for an overall charge of roughly zero (electrically quasi-neutral medium).
Those particles dissolved in the plasma are chemicals like electrolytes, proteins, glucose.

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4
Q

What is the osmolality of the plasma?

A

Typically, the osmolality of the plasma is about 280-310 mOsm/kg in most healthy animals

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5
Q

What is the plasma osmality of some birds>

A

▸ African Grey: 288-324 mOsm/kg
▸ Hispaniolan Amazon: 308-345 mOsm/kg
▸ Red-fronted macaws: 223-369 mOsm/kg

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6
Q

What are the principle electrolytes in plasma?

A

Anions - and Cations +
▸ mmol/L or mEq/L

Principal extracellular Cation
▸ Sodium

Principal extracellular Anions
▸ Chloride and Bicarbonate

Plasma proteins
- Net negative charge
- Important role in vascular volume

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7
Q

What is oncotic pressure and what plasma protein contributes to this?

A

Form of osmotic pressure exerted by proteins, notably albumin, in the plasma that
usually tends to pull water into the circulatory system
▸ It is the opposing force to hydrostatic pressure

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8
Q

What is the endothelial glycocalyx layer and how does this contribute to fluid therapy?

A
  • Sugar protein coating (proteoglycan, glycoproteins
    and glycosaminoglycans (GAGs)) at the luminal
    surface of the vascular endothelium
  • Contributes to 2% of the plasma volume
  • Essential role in maintaining the normal fluid homeostasis of the body
    a. Protective barrier between blood and vessel wall
  • Permeable to electrolytes and fluids but not larger molecules like albumin if intact!
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9
Q

How can the glycocalyx become damaged?

A

Trauma, sepsis, diabetes, electrolyte imbalance, surgery and overzealous fluid management

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10
Q

Fluid therapy should be individualized and is considered a what?

A

Prescription

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11
Q

When should fluid therapy be instituted?

A
  • Anesthesia period (pre/per/post) lasting longer than 30 minutes
  • Hydration / volemia / perfusion status
  • Electrolytes &/OR Acid-base balance
  • Renal function
  • Cardiac function/cardiovascular status
  • Caloric balance
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12
Q

How does dehydration present in a patient and what might be important history?

A
  • Vomiting/diarrhea, frequency/duration
  • Urination frequency, urine color, thirst
  • Unable to access water/food: level of ambulation/consciousness EX: cervical disk pain/tetraparesis
  • Unable to eat or to drink: trauma to mouth/head, swallowing issue
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13
Q

What would you find on your PE in a dehydrated patient?

A
  • loss of Skin elasticity
  • Eyes: sunken
  • Bladder : small
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14
Q

What are some causes of hypovolemia?

A
  • Hemorrhage secondary to trauma
  • Coagulopathy
  • Neoplasia
  • Gastroenteritis, Pancreatitis, Peritonitis
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15
Q

How does dehydration present in a patient and what might be important history?

A
  • MM dry, pale or dark, CRT >2 sec
  • Heart Rate: Tachycardia
  • Blood Pressure: PA Systolic <90 mmHg
  • Perfusion and BP issues
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16
Q

What are some lab values you should analyze in fluid therapy and should you reevaluate any throughout TX?

A

o PCV, TS
o Urine specific gravity
o Chemistry
▪ Electrolytes panel, acid-base status, BUN, Albumin (>1.5 g/dl), creatinine
o CBC (Hb >5-7 g/dl)
o Blood lactate

Reevaluate all of them

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17
Q

What are the 2 major types of fluid?

A

A. Crystalloids
B. Colloids

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18
Q

What type of fluid is used most often?

A

Crystalloids

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19
Q

What are crystalloid fluids?

A
  • Water based solutions with small molecules like electrolytes, glucose and buffer, permeable to
    capillary membrane.
  • Interstitial volume replacement solutions
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20
Q

Crystalloids are used for treating what?

A

dehydration and electrolyte derangements and correcting free water deficits.
▸ Only 10-25% of crystalloid volume administered IV persists in the vasculature 1 hour after administration

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21
Q

What are the tonicities of crystalloids?

A
  • Isotonic, hypotonic, hypertonic
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22
Q

Fluids that most closely resemble the ECF are

A
  • Isotonic
  • High in sodium and low in potassium
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23
Q

What are some isotonic fluids?

A

Normosol R, LRS, Plasmalyte 148, NaCl 0.9%

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24
Q

When would you use isotonic fluids?

A

Ideal to replace ongoing losses, isotonic dehydration, treat hypovolemic shock, correct electrolytes imbalances
▸ Select a solution according to patient’s need

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25
Q

What are some alkalizing solutions? and what does this mean?

A

LRS, PLASMALYTE 148, Normosol-R
- Metabolism of substrates like lactate, acetate, gluconate to alkalinizing equivalents to reduce acidemia

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26
Q

What isotonic solution is unbalanced?

A

NACL 0.9%

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26
Q

You should avoid administering balanced solutions containing what?? to the same port as whole blood or what will happen?

A

Balanced solution containing calcium (LRS) should not be administered in same port as whole blood or HCO3- to avoid calcium precipitation

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27
Q

Balanced electrolyte solutions may need what added to them?

A

May necessitate the addition of KCl, Ca, MgSO4, etc

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28
Q

NaCl 0.9% is compatible with?

A

Compatible w/ +++drugs, blood products, anticoagulants

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28
Q

When should you use NasCl 0.9%?

A

Usually appropriate only as replacement (not maintenance)
▸ Large volumes IV (> 30 ml/kg): produces metabolic acidosis, can impair renal blood flow,
predisposes to postoperative vomiting

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29
Q

What are some indications that you should give unbalanced isotonic solution instead of balanced like LRS?

A

Metabolic Alkalosis: High in chloride, promotes bicarbonates renal excretion
▸ Hyperkalemia?, hypercalcemia?

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30
Q

What are some hypotonic crystalloid solutions?

A

NaCl 0,45%, D5W, ½LRS or ½ NaCl +2,5% Dextrose, Plasmalyte 56, Normosol-M

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31
Q

Hypotonic solutions contain? and should be administered how?

A

Contain excess water
▸ **Administered in slow infusion

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32
Q

When should you use hypotonic solutions?

A

For hypertonic dehydration (hypernatremia)

33
Q

What is dextrose solution that is available and how is it used? ?

A
  • 5% dextrose in water (D5W) is isotonic only as administered
  • When Dextrose is metabolized, providing energy, it leaves “free water”
    a. can result in a hypotonic solution
  • May be added to other balanced electrolytes solutions (2.5% or 5% dextrose)
    a. Hypertonic when administered, but approaches isotonicity as dextrose is metabolized
34
Q

What are some hypertonic crystalloid solutions?

A

NACL 5-7.5% in water

35
Q

When should you use hypertonic NaCl 5-7.5%?

A

For emergency, hypovolemia/shock transient therapy
▸ Small doses (4-6ml/kg, IV bolus) rapidly restores circulating volume to hypovolemic patients:
osmotically draws extravascular fluids into the intravenous space

  • Only temporary and fluid will rediffuse back into extravascular space later
36
Q

You must follow hypertonic solutions with:

A

Must be followed by isotonic solutions, crystalloids or colloids, to maintain circulating volume

37
Q

You should avoid hypertonic solutions in:

A

severely dehydrated/hypernatremic patients

38
Q

What are colloids?

A

Water based solutions with both small (permeable) and large (impermeable) molecules

39
Q

Colloids provide volume replacement into what space?

A

▸ Intravascular volume replacement solutions
- Draws fluid into vessels from interstitial and intracellular space for up to 24 hrs

40
Q

What are the natural colloids?

A

plasma, blood, albumin, oxyhemoglobin

41
Q

What are some sythetic colloids?

A

large molecules in NaCl 0.9%

42
Q

Colloids are indicated for:

A

Hypovolaemia:
- shock
- hemorrhage
- circulatory support

Hypoalbuminemia:
- provides oncotic support

43
Q

What is hydroxyethyl starch (HES)?

A

Hetastarch, a synthetic colloid
- Heterogeneous mix with molecular weights ranging from 10,000 to 1 million
- Each gram of HES has the capacity to retain 30 ml of fluid in the intravascular space
- HETASTARCH, PENTASTARCH, TETRASTARCH

44
Q

Why should you use synthetic colloids like HES?

A
  • Immediate/sustained increase in hemodynamics w/comparatively lower risk of fluid overload
  • 100 % of volume infused still in intravascular compartment 1 hour post administration
45
Q

You should follow sythetic colloid fluid with:

A

Followed with crystalloid fluid therapy

46
Q

What can sythetic colloids interfere with?

A

May complicate cross-matching for blood transfusions, interfere w/ hemostasis, $$$

47
Q

What are the total daily doses in animals?

A

Total daily doses should not exceed 20 ml/kg/day for most animals, Cats: 10 ml/kg/day

48
Q

Warning! You should be cautious using sythetic colloids in what patients?

A
  • Current shift away from colloids (or large volumes) in critical care and sepsis
  • Caution w/dehydrated animals, animals with coagulopathy, head trauma, impaired renal
    function (elevated BUN or creatinine concentrations)
  • Adverse effects and toxicities caused by colloidal solutions are dose-dependent
  • Strictly follow guidelines for dosing
49
Q

What are some natural colloid products that can be used for fluid therapy?

A
  • BLOOD AND BLOOD PRODUCTS
  • Fresh whole blood: if Hb < 7 g/dl
  • Packed red cells
  • Fresh frozen plasma, fresh plasma: Coagulation factors, AB
  • Human serum albumin ($$)
  • Oxyglobin
  • Cell-free (stroma-free) crosslinked bovine hemoglobin
  • Canine albumin
50
Q

What are the three goals of fluids when determining how much should be given?

A
  • Replace existing deficits
  • Maintain daily needs
  • Take care of ongoing losses
51
Q

How do you calculate replacement volume in a patient that is dehydrated?

A
  • Replacement volume (L) = Body weight (kg) x % dehydration
  • Replacement volume (ml) = Body weight (kg) x % dehydration (in decimals) x 1000 (1 kg water =
    1000 ml)
  • Ex: 400 kg Mare, 8% dehydrated: 32 L.
  • Ex: 25 kg Dog, 8 % dehydrated (0.08) : 2 000 ml.
52
Q

What are some ongoing losses that indicate fluid therapy?

A
  • Diarrhea, gastric reflux, wound bleeding or oozing
  • Ex: 400 kg Mare, 8% dehydrated, colic: proximal enteritis: reflux 2 L/hour = 48 L/day
53
Q

What are the daily needs (Maintenance) of fluid?

A
  • Patient does not eat or drink but normal losses still occur through urine (≈ 20 ml/kg), feces (≈ 10 ml/kg), skin & respiration (≈ 20 ml/kg) (total ≈ 50 ml/kg/day)
  • Equine: 40-60 ml/kg/24h
  • Dog: 132ml/kg/24h
  • Cat: 80ml/kg/24h
54
Q

How much fluid should be given with existing deficit, daily maintenance, and ongoing losses?

A

Ex: Mare 400 kg: Existing deficit: 32L + Daily maintenance: 16-24L + Ongoing losses: 48 L = 96-104
L/24h for 1st 24 h

55
Q

What should you constantly reevaluate when determining fluid needs?

A

▸ Ongoing losses may vary through the day
▸ Measure PCV/TS frequently (q4-6 hours)
▸ Replace 75-80% of the original deficit over 24 h and reassess needs/dehydration

56
Q

Insensible water loss under anesthesia is:

A

low, rarely exceeding 0.5 ml/kg/h

57
Q

Surgical trauma will cause how much extravasation of fluid on average?

A

The extravasation of fluid due to “average” surgical trauma is less than 1 ml/kg/h

58
Q

Is the administration of fluids to counteract the affects of anesthetic vasodilation inidicated?

A

The administration of a crystalloid or colloid to counteract the effects of anesthetic induced
vasodilatation (i.e. relative hypovolemia) is frequently ineffective and cannot be guaranteed

59
Q

When we give IV fluids under GA we should aim for how much given and whats our goal?

A
  • Aim at a total of 20-30 ml/kg/procedure
  • Adjust fluid amount/type based on assessment/monitoring: GOAL directed therapy
60
Q

How rapidly should the solution be given?

A

depends do we need shock therapy or maintenance therapy?

61
Q

What is maintenance fluid therapy?

A

Cats: 80 * BW (rule of thumb: 2-3 mL/kg/hr)
Dogs: 132 * BW (rule of thumb: 2-6 mL/kg/hr)

Excessively rapid administration of maintenance fluid can result in fluid overload or
electrolyte imbalance

62
Q

What is the shock fluid therapy protocol?

A

Large bore IV catheters
▸ Dogs: 80-90 ml/kg/h, Cats: 50-55 ml/kg/h
▸ Give 25% of calculated dose and reassess

63
Q

The main points of fluid rates during anesthesia are?

A
  • Rule of thumb for cats for initial rate: 3 ml/kg/hr
  • Rule of thumb for dogs for initial rate: 5 ml/kg/hr
  • Lower rates with cardiovascular diseases
  • Fluid pre-op and post in patients with chronic renal disease
  • Reduce fluid rates if procedure lasts > 1 hour
64
Q

What are the differences of continuous and intermittent IV fluid therapy?

A

Continuous rate IV therapy
* Often best, may be unnecessary, impractical or problematic
* Delivered via drip sets/various fluid infusion pumps

Intermittent IV fluid therapy
* Often a practical/effective alternative to continuous IV

The risks of infection at catheter sites, phlebitis, and the dynamic volume requirements in the critically ill

65
Q

When should you do intraosseous fluid therapy?

A
  • Very useful for emergency vascular access
  • Functionally analogous to a large central vein without the collapse!
  • Neonates, exotic species, selected critically ill patients
66
Q

What are the significant risk of IO therapy?

A

▸ Infection
▸ Periostitis
▸ Severe pain
▸ Rarely - loss of limb

67
Q

When should give SQ fluid therapy?

A

▸ Patient must already be reasonably well perfused in order to mobilize SC fluids
▸ Not effective if the patient is edematous

68
Q

You can give these fluids SQ but not what?

A

appropriate only for isotonic fluids without dextrose!

69
Q

What are the risks/complications associated with SQ fluid therapy?

A

Avoid excessive tissue distention: Excessive volume administered in one site increases the risk of
tissue sloughs, infection, and pain

70
Q

How will the success of the therapy be evaluated?

A

GOAL DIRECTED FLUID THERAPY
Pulse rate and quality, Blood pressure
Capillary refill time/Mucous membrane color, Skin turgor
Respiratory rate and effort/Lung sounds
Body weight
Urine output, urine sg
Mental status
Extremity temperature
venous/arterial blood gases
PCV/Total solids/serum lactate/bun/creatinine/electrolytes

71
Q

What is PVI?

A
  • Plethysmographic Variability Index (PVI)
  • Respiratory variations in the amplitude of the pulse oximeter-derived plethysmography pulse
    pressure waveform have been shown to predict fluid responsiveness.
  • Dynamic variables (indices evaluating the response to cyclical changes in venous return, or
    preload) are more predictive of fluid responsiveness.
  • Arterial pulse pressure variation induced by manual or mechanical ventilation has been
    demonstrated to be a specific and sensitive guide to fluid therapy.
  • Respiratory variations in the amplitude of the noninvasively recorded pulse oximeter-derived
    plethysmography (change in volume) pulse pressure waveform have been shown to predict fluid
    responsiveness.
72
Q

When does fluid overload occur?

A

Increase >10% from baseline admission weight

73
Q

what are the clinical signs of fluid overload?

A
  • Pulmonary edema, ascites, peripheral edema
  • Tachypnea, clear nasal discharge, crackles at pulmonary auscultation
  • Chemosis
  • Electrolyte/acid base imbalance, hemorrhage exacerbation, hemodilution, coagulopathy
74
Q

T/F: In general, the choice of fluid is less important than the fact that it is isotonic.

A

True

75
Q

T/F: Volume benefits the patient much more than exact fluid composition

A

true

76
Q

Isotonic fluids wont have a severe negative impact on most:

A

electrolyte imbalances, and their
use will begin to bring the body’s fluid composition closer toward normal pending laboratory
results that will inform the clinician of more specific fluid therapy.

77
Q

When flushing an IVC normal saline is just as good as

A

heparinized saline

78
Q

What solutions may be used in liver disease?

A

LRS or acetated Ringer’s solution may be used in liver disease. LRS contains both D- and Llactate and is unlikely to increase blood lactate levels

79
Q

T/F: Use of K-containing balanced electrolytes solution does not increase blood K in cats w/urethral
obstruction

A

True

80
Q

Can you use fluids in HCM patients?

A

Patients with subclinical HCM may be able to tolerate cautious fluid boluses for hypotension if
their volume status is questionable, but they should be closely monitored for fluid overload &
congestive heart failure

81
Q
A

Anesthesia (7 decks)

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