Potassium Balance

Normal 3.5-5mmol/l

Hyperkalaemia

Causes

Input	Distribution	Excretion
Excess K therapy Blood transfusion	Rhabdomyolisis burns oncology Cellular (cf insulin)	Renal failure Renin-Angiotensin-Aldosterone inhibition (aldosterone promotes Na reabsoprtion at expense of K excretion) ACEi K-sparing diuretics Addison's disease (adrenal insufficiency)

Consequence: VF arrest

> 6.5mmok/l needs urgent treatment (leads to arrest - hence used as cardioplegic solution)
Symptomatic
ECG changes:
- Tall tented T-waves (T-pot), increased PR
- Wide QRS
- Sinusoidal pattern

Management

Recheck potassium
Cardiac monitoring
Pharmacological treatment
- 10ml calcium gluconate (10%) IV over 2 mins (cardioprotection)
- 20U Insulin + 50ml 50% Dextrose IV (drives potassium into cells)
- Nebulised salbutamol 2.5mg
- Calcium resonium 15g/8hours PO
Dialysis (persistently high K / pH <7.2)

Hypokalaemia

Input	Distribution	Excretion
Decreased oral intake / starvation	Alkalosis / insulin excess Artefact - sampling from drip arm	GIT losses: vomiting, diarrhoea, fistula Renal losses: Conns, cushings, diuretics, RTA

Management

Replacement

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