Yr 2 3 Fluid Replacement Solutions Flashcards

1
Q

Fluid compartments

A
  1. body water - 60% adult body weight
  2. Body water - 80% neonate
  3. ECF
    -20% body WEIGHT
    OR
    -1/3 total body WATER (Na+ main cation)
  4. ICF
    -40% BW
    -2/3 body water (K+ main cation)
  5. Interstitial fluid
    - 15% body weight
    OR
    - 1/4 total body WATER
  6. Intravascular fluid
    5% bodyweight
    or 1/12 total body water
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2
Q
For 500kg horse work out
ICF
ECF
Interstitial fluid
Intravascular fluid
A

ECF - 20% BW = 100kg
ICF - 40% BW = 200kg
Interstitial - 15% BW = 75kg
IVF - 5% BW = 25kg

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3
Q

30kg dog, 10% dehydrated and has a fluid deficit of 3L. How much fluid is missing from plasma?

A
  1. 10% fluid deficit = 3L
  2. check lec
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4
Q

What does dehydration result in?

A
  1. Fall in blood volume
  2. = Fall in blood pressure
  3. activation of baroreceptor reflex and RAAS
  4. baroreceptor - medulla oblongata - inc sympathetic, dec parasympathetic
  5. RAAS - inc renin release from JG cells
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5
Q

How do we give fluids?

A
  • Enteral- Ideally use the natural route i.e. the gut, Oral voluntary intake, Via tube
  • Parenteral- IV, Intra-osseous, Intra-peritoneal, SC
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6
Q

Oral fluid therapy

  1. what is it based on?
  2. when do you sue
  3. what do you rely on
A
  1. Based on
    o Active sodium-glucose co-transport
    o Equimolar Na & Glucose = much more fluid is reabsorbed
  2. Use when mild/ moderate fluid volume disturbances-
    - Severe decrease in BP will result in vasoconstriction which reduced absorption of water from the GI tract
  3. relies on gastrointestinal tract functioning
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7
Q

How has the development of oral fluids changed

A
  1. 1st gen equimolar glucose and Na
  2. 2nd gen - additional bicarbonate to reduce risk of metabollic acidosis as lot of HCO3- lost in diarrhoea
  3. 3rd gen - higher glucose - esp important for young nutritional demands
  4. glutamine which promotes villus repair and regeneration as D causes atrophy. Atrophy = no normal absorption
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8
Q

How to choose oral fluid

A
  1. Rehydration ability
  2. Ability to correct acidosis.
  3. How much glucose?
  4. Nutritional ability & prevention of villus atrophy to help maintain growth - glutamine is expensive
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9
Q

scouring 40kg calf

advise to farmer

A
  1. give ASA scour starts
  2. Give most natural way for calf to suckle - teat. If no drink then stomach tube
  3. 40kg calf = 4-8 litres daily
  4. Give little and often
  5. Decide on product
  6. DO NOT STOP FEEDING MILK as this causes more villus damage and atrophy
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10
Q

Types of parenteral fluids

A

Crystalloids and Colloids

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11
Q

Crystalloids

A

a. Salt solutions that that freely cross capillary walls. (most electrolytes are v small molecules so can pass inbetween)
i. Stay in vascular space for short time (freely cross). Quickly (mins) leak into extracellular fluid compartment

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12
Q

Colloids

A

a. Non crystalline substances consisting of large molecules diluted in a crystalloid. Capillary endothelium is impermeable to these large molecules so tend to stay in vascular space

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13
Q

Crystalloids more in depth

A
  1. electrolyte solutions

2. give either non physiological or physiological solutions

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14
Q

Talk about crystalloids physiological and non physiological solutions

A
  1. non physiological solutions
    - 0.9% NaCl
    - Has tonicity similar to plasma but is a non physiological, chloride rich unbalanced salt solution
    - Because if analysed ECF it contains a lot more than Na and Cl
  2. physiological
    a. Isotonic to plasma and designed to mimic plasma so:
    - Are buffered
    i. Can contain HCO3
    ii. or more often – contain molecules (such as acetate, gluconate, and lactate) these anions are metabolised in the liver produce of HCO3-
    c. Balanced
    i. contain electrolytes in addition to Na+ and Cl- (such as K+ Ca2+ Mg2+ ), making them similar to protein free plasma. Lactated Ringer’s is an example of a balanced solution.
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15
Q

What sort of solutions can crystalloids be?

A
  1. isotonic
  2. hypertonic
  3. hypotonic
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16
Q

Isotonic crystalloid solutions

A

• These have the same concentration of electrolytes as plasma and are therefore isosmotic (same number of particles) with plasma when they are administered into the circulation.
• E.g. 0.9% Na Cl
o Most solutions have a high [Na+ ] and therefore similar to ECF rather than intracellular fluid
• Are poor plasma volume expanders as less than 25% of solution injected into vein is retained in vascular space within 30 mins.
o If inject 250ml into 30kg dog, it won’t stay very long  as you are putting into vasculature it empties out into extracellular space
• Within 1 hour, 75% of isotonic crystalloid has moved into the extravascular space. i.e. fluid quickly distributes within extracellular fluid compartment

17
Q

Hypertonic crystalloid sollutions

A

Result in fluid accumulation in intracellular space
• Considered to be plasma expanders because their inc tonicity causes water to move from interstitial and intracellular sites into the intravascular compartment • E.g. 7.2% NaCl solution (8X more conc what normal saline!
o High conc salt conc into ECF, water moves in, inc blood volume and therefore pressure

18
Q

Hypotonic crystalloid solutions

A

• These have a lower concentration of electrolytes than plasma but are isosmotic with plasma when they are administered into the circulation.
o 5% dextrose in water is isotonic when it enters the circulation but dextrose (glucose) is a penetrating solute and so
o dextrose enters cells and is metabolised
o a 5% dextrose (form of glucose) solution is therefore hypotonic as effectively you are administrating water
o dextrose sued up so left with water

19
Q

Why would you use a hypotonic crystalloid solution when something is going to end up as water?

A

o Fluid therapy si often aimed at expanding plasma volume BUT NOT ALWAYS!
o Face trauma – animal can’t drink
o Doesn’t need high Na all time

20
Q

Tonicity vs osmolarity

A
  1. O - describes number of particles between 2 solutions, determines where water will move (high to low conc)
  2. T - what happens between cells and body fluids. Cell membranes have different permeabilities
21
Q

Colloids

A

• Colloids – Large molecules (5 – 1000kDa) thus can’t pass through healthy vascular endothelium
o Therefore they inc colloidal osmotic pressure of the plasma & “pull” water from the interstitial space = PLASMA VOLUME EXPANDERS

22
Q

When would you use colloids?

A

difficult to administer sufficient volumes of fluids rapidly enough to resuscitate a patient (e.g., large patient, emergency surgery, large fluid loss).
• When decreased oncotic pressure is suspected 1. E.g. hypoproteinaemia
• Often use crystalloids with them: as wanna make sure there is fluid going into animal

23
Q

What is a colloid?

A

• Colloids are water-based solutions with a molecular weight too large to freely pass across the capillary membrane

24
Q

What are the diff types of colloid?

A

Natural: whole blood, plasma, albumen: When animal requires RBSs, clotting factors or albumin, blood products are colloid of choise
2. Synthetic - starches, gelatins, dextranss

25
Q

Adverse effects of colloids

A

o Anaphylactic reactions
o Coagulopathies
o Oedema (also a risk with crystalloids and basically ALL fluid therapy

26
Q

What is the maintenance fluid requirement of a normal 12 kg dog?

A

50ml/kg in 24 hrs = 600 mls per day

27
Q

How is a intravenous solution containing NaCl 7.2% best described

A

Hypertonic crystalloid solution

28
Q

Major difference between 2nd and 3rd gen oral replacement fluids

A

third gen contain more glucose than 2nd

29
Q

Approx ECF 100kg calf

A

20L