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Lecture 1.2: Body Fluids Flashcards

1
Q

How much of the body is water (Total Body Water)?

A

60%

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2
Q

How much of TBW is intracellular?

A

40%

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3
Q

How much of TBW is extracellular? How is it split up?

A

20%
Interstitial (15%)
Intravascular (5%)

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4
Q

Does adipose or skeletal muscle tissue have more water?

A

Skeletal Muscle Tissue

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5
Q

What Cations are found in Extracellular Fluid?

A
  • High Sodium (Na +) ~140mmol.l-1
  • Low Potassium (K+) ~4.5mmol.l-1
  • Very low Calcium (Ca2+)
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6
Q

What Anions are found in Extracellular Fluid?

A
  • Chloride (Cl-) ~100mmol.l-1
  • Hydrogen Carbonate (HCO3-) ~26mmol.l-1
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7
Q

What Cations are found in Intracellular Fluid?

A
  • High Potassium (K+) ~160mmol.l-1
  • Low Sodium (Na+) ~10mmol.l-1
  • Very low Calcium (Ca2+)
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8
Q

What Anions are found in Intracellular Fluid?

A
  • Chloride (Cl-) – lower concentration than extracellular
    fluid
  • Lots of organic anions
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9
Q

What is Movement of Fluids driven by?

A
  • Osmotic forces
  • Oncotic pressure
  • Hydrostatic pressure
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10
Q

What generates osmotic forces?

A

Changes in the concentration of solute (electrolytes) in the fluid compartments

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11
Q

What is the volume of the Intracellular Compartment determined by?

A
  • Movement of water to and from the extracellular
    compartment
  • Mostly determined by solute concentration in the
    extracellular compartment
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12
Q

What is an Isotonic Solution?

A

Same solute concentration in intra and extracellular compartment

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13
Q

What is a Hypotonic Solution?

A

Lower solute concentration in extracellular compartment

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14
Q

What is a Hypertonic Solution?

A

Higher solute concentration in extracellular compartment

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15
Q

Changes in the Extracellular Composition damages cells through what mechanisms? (3)

A
  • Osmolality changes produce swelling or shrinkage of
    cells
  • Electrolyte changes alter excitable cell function
    (K+ and Ca2+ are very significant)
  • Changes in intravascular volume affect tissue
    perfusion leading to cell damage from lack of oxygen
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16
Q

What is the distribution of volume between INTERSTITIAL and INTRAVASCULAR
compartment determined by?

A

Exchange of water and solute with interstitial fluid at the capillaries

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17
Q

Where does Interstitial and Intravascular compartment
exchange occur? How does it occur? (4)

A
  • At the capillaries
  • Water and small solutes cross freely
  • Forced out of intravascular compartment by
    hydrostatic pressure
  • Drawn back in to intravascular compartment by
    oncotic pressure
  • Cells and large molecules do not cross freely
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18
Q

What is the pressure which is generated by the presence of large molecules called?

A

Colloid Osmotic Pressure

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19
Q

75% of oncotic pressure of the plasma comes from…?

A

Albumin (anion)

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20
Q

What is the aim of oncotic pressure?

A

To keep the fluid in the intravascular compartment

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21
Q

What causes water to move into the interstitial compartment from the intravascular compartment? (2)

A
  • Loss of protein intravascularly
  • Increase of protein in interstitial compartment
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22
Q

What complication arises from increased interstitial fluid?

A

Oedema

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23
Q

What is Hydrostatic Pressure?

A

The pressure that any fluid in a confined space exerts

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24
Q

What is the overall interaction of Oncotic and Hydrostatic pressure is known as?

A

Starling’s Principle

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25
Daily values of fluid input? (3)
* Oral Fluid Intake (~1500ml) * Food (~500ml) * Metabolism (~500ml) * Total ~2500ml
26
Daily values of fluid output?
* Urine (~1500ml) * Insensible Loss (sweat, faeces, lungs) (~1000ml) * Total ~2500ml
27
What causes Risk of Fluid Deficit (11)
* Vomiting * Diahorrea * Haemorrhage * Fistulae * Pyrexia * Burns * Diuresis * Diuretic Drugs * '3rd Space Losses' * Patient too ill to drink * Carer neglect
28
What causes Risk of Fluid Overload (4)
* Acute or Chronic Renal Failure * Heart Failure * Liver Failure * Iatrogenic (i.e. excess IV fluids)
29
What is the aim of Fluid Replacement Therapy? When are IV fluids prescribed?
* Aim to replace what has been lost * Correct existing deficits and/or ongoing losses * IV fluids are prescribed when fluid needs can't be met by enteral routes (oral)
30
What is an important consideration when doing Fluid Replacement Therapy?
* Need to consider the correct fluid therapy
31
What are the 3 Types of Fluid Therapy?
* Maintenance Fluids * Replacement Fluids * Fluid Resuscitation
32
What do Maintenance Fluids deal with?
The daily necessary fluid requirements
33
How are Maintenance Fluids administered?
* Oral (minor dehydration) * Enteric (NBM/ severe dehydration- unable to take orally) * Intravascular route (dehydration, NBM etc)
34
Maintenance Fluid Requirements (3)
* 25-30ml/kg/day Water * 1mmol/kg/day Potassium, Sodium, Chloride * 50-100g/day Glucose (to limit starvation ketosis) this does not address patients nutritional need
35
Maintenance Fluid Requirements: What demographic of patients should more cautious fluid prescription (20-25mls/kg) be done for?
* Elderly * Patients with renal or cardiac failure * Patients at risk of re-feeding syndrome
36
Maintenance Fluid Requirements: How are they adjusted for obese patients?
* In obese patients you adjust the prescription (electrolyte need) to their ideal body weight and the lower range for volume/kg (25mls/kg) * Patients rarely need >3L/day
37
What is Fluid Resuscitation?
* It is the medical practice of replenishing bodily fluid lost through sweating, bleeding, fluid shifts or other pathologic processes * The primary goal of fluid resuscitation is to increase cardiac output and improve organ perfusion
38
What are the 2 ways in which Fluid Resuscitation is used?
1) Maintain intravascular volume (In order to maintain blood pressure in hypotensive or shocked patients) 2) To replace massive fluid loss
39
What are the 2 (*3) Types of Fluids?
* Colloids * Crystalloids * Blood
40
What is the composition of Colloid Fluids?
* Solution of larger organic molecules (protein), water and electrolytes * Albumin, Gelofusine, Gelaspan
41
What is the composition of Crystalloids Fluids?
* Solution of small molecules in water * Sodium Chloride, Hartmann’s, Dextrose * Physiological – A more physiologically balanced Crystalloid
42
What is the MOA of Colloid Fluids?
* The large particles (mostly proteins) are too large to pass the capillary membrane * Creates oncotic gradient holding the water in the intravascular space * Colloids remain in the intravascular space longer than crystalloids * Maintains high oncotic pressure in the intravascular space
43
What Risk is associated with Colloid Fluids?
Anaphylaxis
44
Examples of Crystalloids ?
* 0.9% Saline +/- Potassium * Physiological crystalloids – Hartmann’s, Plasmalyte148 * Glucose
45
0.9% Saline Sodium Concentration
Sodium concentration higher (154 mmol/l) then plasma (140 mmol/l)
46
What risks are associated with 0.9% Saline? (2)
* Extra Chloride (154) can lead to hyperchloraemic acidosis * No potassium can lead to hypokalaemia
47
When is Glucose Solution useful? Why?
* Useful in dehydration * Not helpful for resuscitation * Because it is relatively isotonic
48
What happens to glucose when administered?
However glucose is rapidly metabolised = water in the extracellular space
49
What are Physiological Fluids? Examples?
* Part of the Crystalloid family * Much closer in electrolyte & colloid composition to plasma * Less physiologically disruptive than 0.9% Saline * Hartmann’s * Plasmalyte148
50
What is the half-life of Crystalloids?
30-60 mins
51
What is the half-life of Colloids?
Several hours or days
52
How much volume of Crystalloids is needed for fluid replacement?
3 times the volume needed for replacement
53
How much volume of Colloids is needed for fluid replacement?
Replaces volume for volume
54
What can excessive use of Crystalloids cause?
Peripheral or Pulmonary Oedema
55
What can excessive use of Colloids cause?
Can precipitate cardiac failure
56
How do Crystalloids affect the intravascular spaces?
Molecules small enough to freely cross capillary walls, so less fluid remains in intravascular spaces
57
How do Colloids affect the intravascular spaces?
Molecules too large to cross capillary walls, so fluid remains in intravascular spaces for longer
58
How costly are Crystalloids?
Inexpensive
59
How costly are Colloids?
Expensive
60
Can Crystalloids cause allergic reactions?
Non-Allergenic
61
Can Colloids cause allergic reactions?
Can cause Anaphylaxis
62
Are Crystalloids suitable for vegetarians and vegans?
Yes
63
Are Colloids suitable for vegetarians and vegans?
Some preparations are not suitable for vegetarians and vegans
64
Which Fluid should be used for Maintenance?
Crystalloid Solutions ideally a more physiological fluid
65
Which Fluid should be used for Resuscitation?
* Crystalloid for initial fluid boluses of 500mls/<15mins * Up to 2000mls and then consider colloid
66
Which Fluid should be used for Blood Loss?
Colloid (for rapid plasma expansion) while awaiting blood
67
Colloids and Crystalloids are plasma volume .....?
expanders
68
What are the 5 R's
* Resuscitation – ABCDE assessment (initial fluid resuscitation with bolus) * Routine Maintenance – for those at risk of ongoing fluid loss * Replacement – ensure adequate: hydration, electrolyte balance * Redistribution – Be aware of redistribution into the tissues * Reassessment – Regular reassessment

Membranes and Receptors (19 decks)

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