Hyperkalaemia Flashcards
What is the normal K+ mmol/L level of the blood?
3.6 - 5.2mmol/L
What is hyperkalaemi? Severe?
- Raied K+ levels above 5.2mmol/L
* Severe hyperkalaemia is >7mmol/L
What are the 4 main catergories when thinking of the cause of hyperkalaemia?
- Decreased excretion
- Increased release from cells
- Increased extraneous Load
- Spurious -not genuine
What are the causes of decrease excretion of K+?
- AKI
- Drugs
- Addison’s disease
- Acidosis
- Aldosterone deficiency
What drugs can cause decreased excretion of K+?
- Amiloride (K+ sparing diuretic)
- Spironolactone / epleronone (K+ sparing diuretic)
- ACEi / ARBs
- NSAIDs
- Ciclosporins
- Heparin
What are the causes of increase K+ release from cells i.e. decreased Na+/K+-ATPAse activity
- Diabetic ketoacidiosis
- Acidosis
- Rhabdomyolosis/tissue damage
- Tumour lysis
- Digoxin poisoning
What is aldosterone action on K+?
Aldosterone stimulates K+ and H+ secretion in exchange for Na+ and H20 at the collecting duct
Why is hyperkalaemia cardiotoxic?
*As high K+ outside cells inactivate Na+ channels
How does insulin work on K+? What must it be accompanied with?
Drives K+ into cells, but must be accompanied with glucose to acoid hypoglycaemia?
What is the presentation of hyperkalaemia?
- Asymptomatic
- Muscle weakness
- Kussmaul respiration due to metabolic acidosis
- Decreased cardiac excitability causing: hypotension, bradycardia and eventual asytole
What are the ECG changes of hyperkalaemia?
- Tall tented T waves
- Reduced P waves
- Widened QRS complex
- Sine wave pattern =pre-cardiac arrest
What is the management of hyperkalaemia?
- A-E assessment + GCS
- Protect myocardium:
>10mL of 10% calcium gluconate IV over 5mins - Drive K+ into cells
>Insulin 10units + 50mL of 50% glucose IV over 10-15mins
4.Regular checks of blood glucose and plasma K+
