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Sita GenitoUrinary System > Lecture 20: Clinical Problem Solving: Electrolytes > Flashcards

Lecture 20: Clinical Problem Solving: Electrolytes Flashcards

1
Q

Questions to Ask patient before giving them IVF

A
  1. Euvolaemic, hypovolaemic(dehydrated) or hypervolaemic (fluid overload)
  2. Does my patient need IV fluid? why?
  3. How much
  4. What type(s) of fluid does my patient need
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2
Q

Types of IVF fluid

A

Hypotonic fluid
Hypertonic fluid
Isotonic fluid

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3
Q

Hypotonic fluid

A

Dilute/ Lower concentration than cell (as osmosis goes Low –> High, as H2o makes it equal)
Pushes fluid into cells –> Makes cells fat (swollen/hippo)
1. 5% Dextrose (even though originally appears to be isotonic)
-Starts isotonic –> dextrose metabolised by cells –> free water (hypotonic)
- patients with high Na serum or fluid overloaded

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4
Q

Hypertonic fluid

A

Higher concentration than inside cell (as osmosis goes Low –> High, as H2o makes it equal)
Pushes fluid out of cells –> makes cells smaller
- too much Hypertonic fluid can kill people

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5
Q

Isotonic fluids

A

Keeps everything the same

  1. Plasmolyte
  2. Normal saline 0.9%
    - generally always given isotonic fluid –> unless maintenance fluid and overloaded or High Na (want to give extra H2O)
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6
Q

Assessing volume status

A

Euvolaemic, hypovolaemic(dehydrated) or hypervolaemic (fluid overload)

  1. Weight: massive weight gain or loss after surgery = majorly overloaded/dehydrated
  2. Dry tongue: not super useful unless incredibly dry and cracked
  3. ODema
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7
Q

Symptoms/Signs of Hypervolaemia/Fluid overload

A

Weight gain
Swollen ankles and puffy eyes (oedema)
High blood pressure
Breathlessness (Fluid in lungs)

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8
Q

Symptoms/Signs of Hypovolaemia/ Dehydration

A

Weight loss
Dry mouth
Low blood pressure
Dizziness (Less blood to brain)

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9
Q

When doesnt your patient need IV fluid?

A

drinks enough
enteral feeding
already fluid overloaded

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10
Q

When does your patient need IV fluid

A

not drinking

has lost/is losing fluid

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11
Q

Why does a patient need IV fluid?

A
  1. Maintenance
  2. Replacement of Losses
  3. Rescuscitation
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12
Q

Maintenance with IV fluid

A

Lost fluid via: Pee, Poo, Sweat, Breathing (lungs) –> 2-3 L/day of fluid lost
Skin + Lungs: Lose 1L/day
Urine: 1.5 L/day
Poo: 100ml/day
THEREFORE:
- 2-3L/day of IV fluid is needed to maintain the body to keep normal functions going, if cannot get via eating/drinking

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13
Q

Maintenance fluids re Paediatrics

A

4mL/kg/hr fro the first 10kg of body weight
+ 2mL/kg/hr for the next 10 kg of body weight
+ 1mL/kg/hr for the remainder of body weight
–>
Baby loses 10 kgs: 40ml/hr
Baby loses 20kgs: 60ml/hr
Baby loses 30kgs: 70ml/hr

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14
Q

Cholera

A

Massive diarrhea –> lose fluid

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15
Q

Replacement with IV fluid

A

Replacing fluid loss AS WELL AS MAINTENANCE FLUID
Careful assessment of fluid status (weight)
Helpful measurements:
1. Weight
2. JVP
Patient record of losses: fluid balance charts (IV infusions, drains, stents, oral and nasogastric)

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16
Q

Pathologies requiring fluid Replacement

A
  1. Diarrohea
  2. Vomiting
  3. 3rd spacing
    - Weight and JVP are good measurements
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17
Q

Third spacing

A

a pathology (alongside diarrohea and vomiting) causing fluid replacement
ECS where fluid is normally present and physiologically useless–> can accumulate
1. Tissue spaces (oedema)
2. Abdomen (ascites)
3. Pleural space (pleural effusion)
4. Pericardial space (pericardial effusion)

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18
Q

Resuscitation with IV fluid

A

shocked patient 60/90 BP –> requires rapid replacement (1L of fluid over 20 mins)
- some people need alot of intravenous fluid if you are resucitating them (ICU)

19
Q

What type of IV fluid

A
  1. Fluid status
  2. Serum Sodium
    - safest fluid is generally isotonic –> Na and H2O given in balance –> wont ruin the tonicity of cells
20
Q

When do you give Isotonic fluid?

A

Generally given in most cases
Except:
- High Na (give hypo as insufficient water)
- Maintenance and overloaded (give hypo)

21
Q

When do you give Hypotonic fluid?

A

5% Dextrose starts off as isotonic –> dextrose metabolised by cells –> become free water –> Hypotonic
Patients with (who cant take isotonic fluid):
1. High serum Na (not enough water)
2. Patients needing maintenance fluid but already Fluid overloaded

22
Q

Hyponatraemia

A

“Hypo”= less “natraemia”= Sodium

  • Excess H2O is the problem
  • disorientated and drowsy
23
Q

Body compartments re Water

A

Both genders: over 1/2 body is made up of water
Less body water is in BV when take blood test
Female: Total body mass: 45% solids, 55% fluids
Male: Total body mass: 40% solids, 60% fluids.
- Total body fluid: 2/3 ICF, 1/3 ECF
- Total Extracellular fluid: 80% Interstitial (outside and b/w tissue cells), 20% plasma (in capillaries)

24
Q

Fluid Electrolyte Composition

A

Extrac: High Na
Intrac: High K

25
Q

Where are IV fluids going?

A

Extracellular compartment

26
Q

Water absorption

A
  1. Sensing Dry/Hypotensive:
    a. Osmoreceptors –> detect increased osmotic pressure
    b. Baroreceptors –> detect decreased BP
  2. Stimulating ADH from posterior pituitar
  3. Vascular and Renal changes
    a) Vasoconstriction of BV
    b) Increase renal absoprtion of H2O into ECF
  4. Increased BP and Volume (hydration status)
    Note: can go wrong with ADH
27
Q

Causes of Hyponatraemia

A
  1. Water excess (excessive drinking or ADH)
  2. Sodium loss
  3. Pseudohyponatraemia (lab tests say have low Na but you actually dont)
    Lab results:
  4. Low Plasma: Na, K, Cl, glucose –> low plasma osmolality
    Note: due to Plasma osmolarity is mainly determined by Na
  5. Increased Urine: Na
28
Q

Main causes of Na loss

A

Na loss –> causes H2O loss

  1. GI loss: Diarrohea and Vomiting
  2. Hypoaldosteronism (no Na into ECF)
  3. sweat (excessively unusual)
  4. diuretics
29
Q

Alsoterone

A

Aldosterone pushes NA2+ tubule –> Blood (reabsorbed) –> H2O follows
Low Aldo = Less Na reabsorption = High K in blood
-Na lost in urine down the gradient
- no counter transporter of K as no Na drive

30
Q

Potassium levels during Hypoaldosteronism

A

High K levels

As no Na countercurrent outwards/reabsorption to drive K movement into cell

31
Q

Pseudohyponatremia

A

Lab tests say have low Na but actually dont
Due to:
1. Hypertriglyceridemia (high plasma lipid/fat levels)
2. Hyperproteinemia (high plasma protein levels)
- some analyses cannot analyse Na properly in the face of very abnormal protein or lipid levels in blood
THEREFORE:
need to take SERUM osmolalities (not just plasma, as will stay normal due to only 2x Na, glucose and urea being accounted for)

32
Q

Water Excess

A

Due to:
1. SIADH ( PP is producing high levels of ADH but you arent hypertensive of hyperosmotic)
2. Polydipsia (excessive water drinker/consumption)
Syndromes with excessive water:
1. Cirrhosis/Liver Failure
2. Heart Failure
3. Nephrotic Syndrom (oedema)
Can appear Euvolaemic –> looks completely normal –> problem due to imbalance of ADH

33
Q

How clnincaly approach Excessive Water levels

A
  1. History: vomiting/diarrohea, dehyration, medication
  2. Examination: Fluid status
  3. Osmolality: Plasma vs Urine (dilute –> polydipsia/SIADH)
34
Q

How do you know the osmolality of Hyponatraemia?

A

Low

As Osmolality is mainly determined by Na levels

35
Q

What is the diagnosis if Osmolality if normal?

A 
Calculated osmolality (mmol): 2x Serum Na + Serum glucose + Serum Urea
Note: Pseudohyponatraemia: measured osmolality is normal as its measurement ISNT effected by hypertriglyceridemia or hyperproteinuria --> therefore need to take serum osmolality
36
Q

Psuedohyponatraemia Osmolality

A

Appears normal as hypertriglyceridemia or hyperproteinuria isnt included in measurement (only 2x Na + glucose + urea)

37
Q

Water excess with Euvolaemia

A

No signs of dehydraton or oedema; JVP not elevated
No evidence of fluid overload
- SIADH
- Polydipsia
- Overhydration with Hypotonic fluids /Low Na Iv fluids (dextrose 5% not saline)
- diuretics

38
Q

Water intoxication/Primary Polydipsia

A

Urine osmolarity unusually high in hyponatraemia
exception is in polydypsia/water intociation
Cannot pee H2O as much as you are drinking

39
Q

ADH release

A

Usually appropriate
Due to low BP or Dehydration
- Sensed by osmoreceptors and baroreceptors
- Causes increase water reabsorption into vasculature –> more concentrated urine –> high osmolarity in urine than blood

40
Q

SIADH Sudden Inappropriate ADH release

A

ADH release despite not being dry/dehydrated/hypotensive
- Kidneys hold onto excessive H2O
Causes:
1. Tumours (small cell carcinoma of lung)
2. CNS (brain tumour)
3. Drugs
4. Lung Disease (chronic)

41
Q

Diuretics

A

Often prescribed to people with High BP
Commonest have Low Na with Thiasides (pee out Na and H2O)
Sodium loss (Lose Na slightly greater than water) –> Hyponatraeumia
Also makes baro-recetpors and osmoreceptors active –> increased ADH
Common cause of Low Na

42
Q

SIADH Sudden Inappropriate ADH release re osmolarity

A

Rest ADH secretion quantity per osmolarity
- Decrease in osmolarity –> continue producing high amounts of ADH
- occurs due to Drugs or SIADH
graph*:
NaCl loss –> reduced ECF volume . shift ADH curve to lower setpoint. ASH systme now allows lower Na concentration ie. ECF osmolarity. ADAPTATION FAVOURS Na instead of K (aldosterone) –> relative wasting of K+
Left shift: 15% decrease in volume/pressure
Right shift: 15% increase in volume/pressure

43
Q

Treatment of Hyponatrauemia

A

Treatment depends on cause (otherwise hyperNa/tonic solutions can cause damaged to brain cells)

  1. Dehydrated patient (with Na loss) –> Saline treatment
  2. Patients with Water excess –> 1. Generally fluid restriction (1L water daily). Rapid correction NOT ADVISABLE i.e. hypertonic fluid (extra Na can cause problem)
44
Q

Rapid correction of Hyponatraumeia with Hypertonic solutions

A
  1. Normal brain – immediate effect of hypotonic state/hyponatraemia –>
  2. Water gain (low osmolarity) –rapid adaptation–>
    - brain wil Decrease in size even though still low Na
  3. Low sodium, potassium and chloride (low osmolarity) –Slow adaptation: lose water–>
  4. Loss of organic osmolites –Lose water–>
    - –improper therapry via rapid correction of hyponatraemia with hypertonic fluids –>
    a) fluid rushes out of brain cells –> brain shrinks (OSMOTIC DELINIATION)
    b) if shrinkage of brain stem –> quadropalysis (blood supply cut off at brain stem) –> paraplegic (decreased consciousness) –> brain damage –> death

Sita GenitoUrinary System (28 decks)

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