Hyperkalaemia Flashcards
What is hyperkalaemia?
This is when there’s too much potassium in the blood.
This is a potential emergency and needs urgent assessment.
What is the main worry of hyperkalaemia?
This is myocardial hyperexcitability leading to ventricular fibrillation and cardiac arrest.
How do you assess hyperkalaemia?
First, assess the patient-do they look unwell?
Is there an obvious cause?
If not, could it be an artefactual result?
Concerning signs and symptoms of hyperkalaemia?
Fast irregular pulse Chest pain Weakness Palpitations Light-headedness
ECG changes in hyperkalaemia
Tall tented T waves
Small P waves
Wide QRS complex (become sinusoidal)
VF
What can cause artefactual results in hyperkalaemia?
If the patient is well, repeat the test urgently.
It may be artefactual, caused by:
Haemolysis
Contamination with K+ EDTA anticoagulant
Thrombocytopenia (K+ leaks out of platelets during clotting)
Delayed analysis
Causes of hyperkalaemia
Organic renal failure K+-sparing diuretics Rhabdomyolysis Metabolic acidosis (DM) Excess K+ therapy Addison's disease Massive blood transfusion Burns Drugs e.g. ACEi, suxamethonium Artefactual results
Non-urgent treatment of hyperkalaemia
-Polystyrene sulfonate resin (calcium resonium 5g/8h/ PO)
binds K+ in the gut, preventing absorption and bringing K+ levels down over a few days.
-If vomiting prevents PO admin, give a 30g enema followed at 9h by colonic irrigation.
Emergency treatment of hyperkalaemia
10ml of 10% calcium chloride (or 30ml of 10% calcium gluconate) IV via a big vein over 5-10 minutes- this is cardioprotective (for 30-60 minutes) but doesn’t treat K+ level.
IV insulin in 25g glucose- insulin stimulates intracellular uptake of K+ lowering serum conc. by 0.65-1 mmol/L over 30-60 minutes.
Salbutamol also causes an intracellular K+ shift.
What happens when hyperkalaemia is not corrected by treatment?
RRT is required if underlying pathology can’t be corrected.
Why isn’t salbutamol used regularly for hyperkalaemia?
High doses are required.
Tachycardia limits use.
