Normal K+ levels
3.5-5.3 mmol/l
Mild hyperkalemia
5.5-6.0 mmol/l
Moderate hyperkalemia
6.1-6.9 mmol/l
Severe hyperkalemia
> 7.0 mmol/l
Causes of hyperkalemia
- sample hemolyzed
- taken from limb with IVI containing K+.
- AKI, patients with CKD
- K+ sparing diuretics (eg spironolactone, amiloride).
- crush injury
- rhabdomyolysis
- burns
- tumor cell necrosis
- massive or incompatible blood transfusion.
- acidosis from any cause (eg DKA), drugs (suxamethonium, β-blockers).
- Addison’s disease
- drug-induced (NSAIDs, ACE inhibitors).
Clinical feature: Hyperkalemia
- M. weakness/cramps
- Paresthesia
- Hypotonia
- Focal Neurological deficits
- asymptomatic -dangerous hyperkalemia
ECG changes: hyperkalemia
- Tall tented T waves
- Small, broad or absent P waves
- Wide QRS
- Sinusoidal QRST (sine wave pattern)
- AV dissociation or VT/VF
Mgmt: mild hyperkalemia
- Treat the underlying cause/hypovolemia
- Specific intervention -diuretic/dialysis
Mgmt: mod hyperkalemia
- Obtain venous access
- monitor ECG
2a. If there are ECG changes, treat as for severe elevation.
2b. If there are no ECG changes, give 10U of short-acting human soluble
insulin with 50mL of 50% glucose IV over 15–30min. - Look for and treat the underlying cause
- consider diuretics (eg
furosemide 1mg/kg IV slowly) and dialysis
Mgmt: severe hyperkalemia
K+ >6.5 mmol/l
- Obtain venous access
- monitor ECG
2a. If no ECG changes:
take another blood sample for U&E, with care to avoid hemolysis, and a
heparinized sample to measure K+ on a blood gas machine.
2b. If ECG changes:
start the tx immediately:
* 10mL of 10% calcium chloride slowly IV (over 5min).
* 10U of short-acting human soluble insulin (eg Actrapid®) with 50mL of 50% glucose IV.
* nebulized salbutamol 5mg, repeated once as necessary.
* Correct volume deficits/acidosis with IV fluids and isotonic (1.26%)
sodium bicarbonate or aliquots (25–50mL) of 8.4%. Beware fluid
overload/osmolar effects, especially in dialysis patients.
* Correct the underlying cause, if possible (eg steroid therapy for
Addison’s disease).
* Contact the nephrology team urgently for patients with acute or chronic
renal failure, as emergency dialysis may be needed.
Treating hyperkalemia in patients taking digoxin with calcium gluconate
Hypercalcemia
may possibly potentiate toxicity in patients on digoxin, so give as an IVI
over 30min in these patients.
Role of insulin in the tx of hyperkalemia
This helps i cellular uptake of K+, lowering
serum levels by up to 1mmol/L within 1hr and lasting up to 4hr.
Role of sulbutamol in the tx of hyperkalemia
This will
lower K+ in most patients, acting in 30min.
Mgmt: hyperkalemic cardiac arrest- follow ALS guidelines for cardiac arrest
- Give 10mL of 10% calcium chloride IV by rapid bolus injection.
- Consider giving 10U of short-acting insulin + 100mL of 50% glucose
rapidly IV. - If there is severe acidosis, give 50mL of 8.4% sodium bicarbonate rapidly IV.
- Consider hemodialysis for cardiac arrest induced by hyperkalemia
which is resistant to medical treatment.
Hypokalemia
<3.5 mmol/l
Severe hypokalemia
<2.5 mmol/l
Sx of hypokalemia
lethargy
weakness
leg cramps
rhabdomyolysis
respiratory difficulties
ECG changes: Hypokalemia
prominent U waves
flattened T waves sometimes mistaken for long QT interval
Mgmt: hypokalemia
- Ensure cardiac monitoring
occurs during any K+ IVI. - Aim to replace K+ gradually.
- The maximum recommended
IVI rate of K+ is 20mmol/hr
Associated Mg+2 def in severe hypokalemia
Many patients with K+ deficiency are also Mg2+ deficient. Consider replacing
Mg2+ in those patients who have severe hypokalaemia.
