Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genitourinary MBCHB2 > Lecture 18: Clinical problem solving: Hyponatraemia > Flashcards

Lecture 18: Clinical problem solving: Hyponatraemia Flashcards

1
Q

What are the questions to ask before giving IV fluid?

A
  • Is my patient euvolaemic, hypovolaemic or hypervolaemic?
  • Does my patient need IV fluid? Why?
  • How much?
  • What type(s) of fluid does my patient need?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is hypotonic fluid?

A
  • Hypotonic solution
  • Lower osmolality, more dilute
  • Pushes fluid into cell
  • Makes cell fat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is hypertonic fluid?

A
  • Hypertonic solution
  • More concentrated, usually more Na
  • Pushes fluid out of cells
  • Makes cells smaller
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is isotonic fluid?

A
  • Isotonic solution
  • Same osmotic pressure across membrane
  • Keeps everything the same
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Its important to ask if youre patient is euvolaemic, hypovolaemic or hypervolaemic.

How do you assess volume status?

A

Must assess if euvolaemic, dehydrated or fluid overloaded.

Fluid overload: Sudden weight gain, oedema (swollen ankles, puffy eyes), high BP, breathlessness.

Dehydration: Weight loss, dry mouth, low BP, dizziness

Measure JVP for both dehydration and fluid overload.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Why would ur patient not need IV fluid?

A
  • Drinking enough
  • On enteral feeding
  • Already fluid overloaded
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the reasons patients need IV fluid

A
  1. Maintenance (nil by mouth)
  2. Replacement of losses i.e diarrhoea
  3. Resuscitation (i.e shock)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

If nil by mouth, how much fluid would you need?

A

You loose 2-3L/D

So 2-3L to maintain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are paediatric needs different when it comes to maintenance?

A
  • 4 mL/Kg/hr for the first 10kgs
  • +2 mL/Kg/hr for the next 10kgs
  • +1 mL/Kg/hr for the remainder of body weight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What would you be replacing when it comes to fluids?

A

Fluids lost to:

  • Diarrhoea
  • Vomiting
  • Burns
  • Effusions i.e ascites
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can you determine the volume of fluid lost?

A

Weight, biggest indicator of rapid weight change // est. of loss/gain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why do you need to give IV fluid for resus?

A

IV fluids given in shock i.e rapid blood loss etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do you determine what fluid to give a patient?

A
  • Look at patient fluid status
  • What is the serum sodium (osmolality status)

Safest fluid generally isotonic unless specific situation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do you generally give in terms of IV fluid?

A

Generally give isotonic fluid unless maintenance fluid and overloaded or high Na

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe how hypotonic fluid works? and whats the warning with it?

A

5% dextrose starts as isotonic but dextrose is metabolised by cells so just becomes free water

Can result in hyponatreamia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When is hypotonic IV fluid useful?

A

Hypotonic solutions useful if high serum sodium i.e not enough water, or if patient needs maintenance fluid but already overloaded

Watch serum sodium!!

17
Q

Why give hypertonic fluid and how does it work?

A

Hypertonic fluid given in hyponatreamia but risks overcorrecting causing major issues.

18
Q

What is hyponatraemia?

A
  • When serum sodium levels are low.
  • Can be caused by excess water
  • Can be due to low sodium but very unlikely entirely because of Na loss.
19
Q

What are the predominant cations and anions in each of the fluids?

A

ECF: High Na (Cation) and High Cl (anion)

ICF: High K (Cation) and High PO4 (Anion)

20
Q

Where do IVF fluids go?

A
  1. ICF

2. ECF

21
Q

Describe ADH release:

A

Brain: Osmoreceptors detect increased osmolarity -> ADH
Baroreceptors: Detect decreased BP -> ADH

ADH

  • > Increased reabsorption of Water
  • > Vasoconstriction of blood vessels

= Increased BP and BV

22
Q

What are the causes of hyponatraemia?

A
  • Sodium loss
  • Water excess
  • Psuedohyponatraemia
23
Q

What causes sodium loss?

A
  • GI loss
  • Hypo-aldosteronism
  • Sweat (not usual)
  • Diuretics
24
Q

What is hypoaldosteronism? (Addisons disease)

A
  • Low serum aldosterone
  • Usually malfunctioning adrenals
  • Low Na -> lost in urine
  • Low BP
  • Pigmentation
  • May have high K
25
Q

Why is there high K in hypoaldosteronism?

A
  • Less Na reabsorbed, thus Na lost in urine down gradient.

- Low Na results in high K in the blood (as no Na/K ATP action)

26
Q

What is pseudohyponatremia?

A
  • Hypertriglyceridemia
  • Hyperproteinemia
  • Osmolality normal in these conditions but sodium is low.
27
Q

What are conditions with water excess?

A 
FLuid overload:
Syndromes with water overload
- Cirrhosis (liver failure + Ascites)
- HF
- Nephrotic syndrome (Oedema)
SIADH
Polydipsia

Can be euvolaemic:
- Excess H2O, but not enough to cause oedema

28
Q

Describe the steps of dealing with a hyponatreamia patient?

A

History:

  • Vomiting/diarrhoea
  • Dehydration
  • Medication

Examination: Fluid status i.e signs of addisions

Osmolality (true vs psuedohyponatremia)

29
Q

Describe what water excess with euvolaemia? and the potential causes:

A

No signs of dehydration or oedema; JVP not elevated

No evidence of fluid overload

  • SIADH
  • Polydipsea
  • Hypotonic IV
  • Diuretics
30
Q

What is a good indicated of water excess/poldipsea in hyponatremia?

A
  • Urine osmolality becomes very low. Usually is is high in hyponatremia
31
Q

What causes syndrome of inappropriate ADH?

A

ADH release despite not being dry or hypotensive

Caused by:

  • Tumours (brain)
  • CNS issues
  • Drugs i.e SSRIs, diuretics
  • Lung disease
32
Q

How can diuretics lead to hyponatremia?

A
  • Low Na with Thiazides
  • Na loss with diuretics
  • Activate baroreceptors and osmoreceptors = Inc. ADH

= Low Na

33
Q

How does a change in NaCl change the set point of ADH?

A

NaCl loss -> reduced ECF volume

Shift ADH curve to lower setpoint

ADH system now allows decreased [Na] , i.e decereased ECF osmolarity

Adaptation favors Na instead of K (aldosterone), i.e relative wasting of K

34
Q

What is the most common cause of low Na in hospital?

A

Use of hypotonic IV fluid…

35
Q

What are the treatments of hyponatraemia?

A

Depends on cause:

Dehydrate pt with Na loss -Give Saline

Water excess = Generally fluid restriction i.e 1L a day. Avoid rapid correction

36
Q

Whats a potential consequence of rapid correction for hyponatremia?

A

Severe osmotic demyelination: = Quadraplegic, loss of consciousness, brainstem damage

Genitourinary MBCHB2 (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions