1: Fluid + Electrolyte - Hyperkalaemia Flashcards
Define hyperkalaemia
Potassium greater than 5.5
What are three causes of hyperkalaemia
- Reduced excretion
- Shift from intracellular to extracellular
- Pseudohyperkalaemia
What causes pseudo-hyperkalaemia
Lysis of cells causing hyperkalaemia due to incorrect taking of blood
What causes hyperkalaemia due to decreases excretion of potassium
AKI
CKD
What endocrine causes of hyperkalaemia
Addison’s
= Aldosterone deficiency
What medications can cause hyperkalaemia
ACEi
Potassium-sparing diuretics
What are two other causes of hyperkalaemia
TLS
Renal Tubular Acidosis
What may cause shift of potassium from intracellular to extracellular
Acidosis B-Blockers Insulin Deficiency Heparin Digoxin
Why does acidosis cause hyperkalaemia
- Excess H+ decreases activity Na+-H+ ATPase
- This leads to reduce intracellular concentration of Na+
- This increases Na+-k+ ATPase and increases extracellular potassium concentration
Describe clinical presentation of hyperkalaemia
- Arrhythmias (AV block, VF)
- Muscle weakness
- Loss deep tendon reflex
- Nausea and Vomitting
- Diarrhoea
What investigations should be ordered in hyperkalaemia
ABG
ECG
RFTs
What are 5 ECG signs of hyperkalaemia
- Tall-tented T waves
- Broad QRS
- Flat P wave
- Sinusoidal (merge T wave and QRS)
- VF
Why are renal function tests ordered in hyperkalaemia
Assess for AKI and CKD as cause of hyperkalaemia
If hyperkalaemia is non-urgent what is used to treat
Calcium resonium
How does calcium resonium reduce serum potassium
Binds potassium in the gut, prevent absorption
How long does calcium resonium take to decrease serum potassium
Days
What hyperkalaemia should be treated urgently
> 6.5 or ECG changes
How is hyperkalaemia immediately managed
IV Calcium Gluconate
Or Chloride
What is the role of IV calcium gluconate
Stabilises cardiac membrane for 30-60 minutes. It does not, lower serum potassium
What is given following calcium gluconate (or chloride) in management of hyperkalaemia
Insulin
What is the role of insulin
Causes shift of potassium from extracellular to intracellular
What else is given in management of hyperkalaemia
Salbutamol
When should salbutamol be given carefully
History IHD - due to tachycardia increasing strain on the heart
What is the main complication of hyperkalaemia
VF
