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Electrolytes and Acid-base disorders > Hyperkalaemia > Flashcards

Hyperkalaemia Flashcards

1
Q

Normal K level

A

3.5 to 5.5 mmol/L

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2
Q

Regulating factors of plasma K level

A
  • Aldosterone
  • Acid-base balance
  • Insulin levels
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3
Q

Foods that are high in potassium

A
  • Salt substitutes = K salts (i.e. contain potassium rather than sodium)
  • Banana
  • Orange
  • Kiwi fruit
  • Avocado
  • Spinach
  • Tomato
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4
Q

Hyperkalaemia >>> Associated acid-base disorder

A

Metabolic acidosis

(In some cases, metabolic acidosis has hypoklaemia with it)

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5
Q

How is metabolic acidosis associated with hyperkalaemia?

A
  • In the DCT >>> in the cell membrane >>> H+ and K+ ions compete with each other >>> for exchange with Na+
  • So, when metabolic acidosis (high H+) >>> K gets less chance to exchange with Na in DCT >>> more K remains in blood >>> Hyperkalaemia
  • And, vice-versa, when hyperkalaemia (high K) in blood >>> fewer H ions can enter the cells >>> metabolic acidosis
  • So, high H+ is proportional to high K+
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6
Q

Causes of hyperkalaemia

A
  • First exclude pseudo-hyperkalaemia (Recheck a fresh sample)
  • Acute renal failure (also CRF)
  • Rhabdomyolysis (can lead to acute renal failure)
  • Drugs: ABCDE Heparin
    • ACE inhibitors, ARBs, Aldactone
    • Beta blocker
    • Cytotoxic agents (>>> Tumour lysis syndrome), Ciclosporin
    • Digoxin
    • Eplerenone (Spironolactone: K-sparing diuretics)
    • Heparin (UFH and LMWH) (By inhibition of aldosterone secretion)
  • Metabolic acidosis
  • Massive blood transfusion
  • Addison’s disease
  • Insulin insufficiency
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7
Q

Pseudohyperkalaemia is known to be associated with - ?

A

Essential thrombocytosis (ET)

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8
Q

Drug causes of hyperkalaemia

A

Drugs: ABCDE Heparin

  • ACE inhibitors, ARBs, Aldactone
  • Beta blockers
  • Cytotoxic agents (>>> Tumour lysis syndrome), Ciclosporin
  • Digoxin
  • Eplerenone (Spironolactone: K-sparing diuretics)
  • Heparin (UFH and LMWH) (By inhibition of aldosterone secretion)
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9
Q

Heparin (UFH and LMWH) >>> how do they cause hyperkalaemia?

A

They inhibit aldosterone secretion >>> hypoaldosteronism >>> hyperkalaemia

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10
Q

Beta blockers >>> how do they cause hyperkalaemia?

A

They interfere with potassium transport into cells → hyperkalaemia

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11
Q

Hyperkalaemia: Features

A
  • General fatures >>>
    • Anxiety
    • Fatigue
  • Cardiac features >>>
    • Mild chest pain (on-off)
    • Palpitations
    • Bradycardia
    • Hypotension
    • ECG changes
    • Life threatening arrythmias (In higher levels & if untreated)
  • Neuromuscular features >>>
    • Numbness tingling
    • Muscle weakness
    • Muscle fatigue
  • Gastrointestinal features >>>
    • Nausea, vomiting​
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12
Q

Hyperkalaemia: ECG changes

A
  • P wave >>> Small P wave (or flattened P wave)
  • QRS complex >>> Widened QRS
  • T wave >>> Tall tented T wave (More suggestive)
  • Sinus bradycardia

​Later leading to >>>

  • Sinusoidal pattern
  • Life threatening (ventricular) arrythmia
  • Asystole
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13
Q

Relation of K level with Beta-blockers and beta-agonists

A
  • Beta blockers interfere with K transport into cells >>> raises K level (A cause of hyperkalaemia)
    • e.g. Atenolol, Metoprolol, Bisoprolol, Esmolol etc.
  • Beta-agonists help with K transport into cells >>> lowers K level (An emergency treatment of hyperkalaemia)
    • e.g. Salbutamol
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14
Q

Beta blocker use in renal failure

A

Contraindicated

As both cause hyperkalaemia >>> Beta blocker use in renal failure can potentially cause severe hyperkalaemia

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15
Q

Surgery in CRF patient

A
  • Postpone surgery until serum K is below 5.5 mmol/l (As CRF has hyperkalaemia)
  • Monitor K immediately after surgery
  • Monitor again 4-6 hours later
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16
Q

Management of hyperkalaemia

A
  • First step: Removal of all cause to prevent cardiac arrest
  • First priority treatment: Stabilisation of the cardiac membrane
    • IV calcium gluconate 10% 10ml over 10mins
      • If question asks 1st line treatment / ECG not done yet / ECG done + abnormal ECG
      • this is also a treatment of hypocalcaemia
  • Second step treatment: Short-term shift of K from ECF to ICF (within cells)
    • 15U Actrapid insulins in 50% 50mol dextrose IV
      • If question asks Tx after Ca.gluconate / treatment to lower serum K/ mentioned normal ECG
    • Nebulised salbutamol
      • Sometimes as emergency Tx
  • Third step: Removal of extra K from the body
    • Calcium resonium (orally or enema)
    • Loop diuretics
    • Dialysis
17
Q

What is the first priority in the management of hyperkalaemia?

A

Stabilisation of the cardiac membrane > by >

  • IV calcium gluconate 10% 10ml over 10mins
18
Q

Aim of treatment with calcium gluconate

A

Stabilisation of the cardiac membrane

19
Q

IV calcium gluconate >>> mechanism

A
  • It acts within minutes AND
  • It works by >>> raising the depolarization threshold for myocytes (>>> cardiac membranes are stabilised)
20
Q

First line treatment in hyperkalaemia

A

IV calcium gluconate 10% 10ml over 10mins

21
Q

Patient with hyperkalaemia (K >5.5mmol/L) + Abnormal ECG: flattened P wave, peaked T wave + others >>> 1st Treatment

A

IV calcium gluconate 10% 10ml over 10mins

22
Q

Patient with hyperkalaemia (K >5.5mmol/L) + symptoms + NO ECG mentioned or done + others >>> 1st Treatment

A

IV calcium gluconate 10% 10ml over 10mins

23
Q

Patient with hyperkalaemia + already given calcium gluconate >>> next treatment

A

15U Actrapid insulins in 50% 50mol dextrose IV

24
Q

Treatments of hyperkalaemia that reduces serum K level by short-term shift of K from ECF to ICF (within cells)

A
  • 15U Actrapid insulins in 50% 50mol dextrose IV
  • Salbutamol nebuliser
  • NaHCO3 IV (debatable, can worse volume overload esp. in renal imp and pulmonary oedema)
25
Q

Aim of treatment with combined insulin + dextrose infusion in hyperkalaemia management

A

Short-term shift of K from ECF to ICF (within cells)

26
Q

Aim of treatment with ‘salbutamol nebuliser’ in hyperkalaemia management

A

It reduces serum K level by short-term shift of K from ECF to ICF (within cells)

27
Q

Patient with hyperkalaemia >>> treatment to lower serum K level

A

15U Actrapid insulins in 50% 50mol dextrose IV

28
Q

Patient with hyperkalaemia + normal ECG + others >>> (First) Treatment

A

15U Actrapid insulins in 50% 50mol dextrose IV

29
Q

Patient with hyperkalaemia + needs emergency treatment >>> Treatment

A

Nebulised salbutamol

30
Q

Patient with hyperkalaemia + given treatment with calcium gluconate and “insulin+dextrose” (or those are not available) >>> 3rd line treatment

A
  • Calcium resonium (oral or enema)
  • Loop diuretics
  • in some cases >>> dialysis
31
Q

Treatment of hyperkalaemia that removes K from the body

A
  • Calcium resonium (oral or enema)
  • Loop diuretics
  • Dialysis
32
Q

Aim of treatment with ‘Calcium resonium (oral or enema)’ in hyperkalaemia management

A

Removal of K from the body​

33
Q

Calcium resonium >>> mechanism

A
  • It is an ion exchange resin
  • When taken orally → prevents potassium absorption from the diet → depletes the body potassium level
  • It takes at least 24-48 hours to have an effect
  • It is NOT suitable as an emergency treatment
34
Q

Aim of treatment with ‘loop diuretics’ in hyperkalaemia management

A

Removal of K from the body (by excretion)

Electrolytes and Acid-base disorders (18 decks)

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