Hyperkalaemia

Question 1

A 70 year old man with end stage renal failure presents to the Emergency Department with generalised weakness. Routine biochemistry reveals a serum potassium of 7.4 mmol/L (3.8-4.9). How would you manage him?

Impression/DDx/Goals

Answer 1

Impression:
This presentation represents hyperkalaemia, which is a medical emergency. This is likely to have occurred in the setting of ESRF and reduced excretion. I am concerned about this presentation as hyperkalaemia can lead to fatal cardiac arrhythmias if left untreated.

Other causes of hyperkalaemia should be considered including:
- increased cell turnover (tumour lysis syndrome, rhabdo, haemolytic conditions)
- metabolic (renal failure, acidosis, adrenal insufficiency)
- medications (K sparing diuretics, heparin, ACEi, B-Blockers)
- spurious (poor venesection sample)
- Missed dialysis given in ESRF

Goals of management:
- Stabilise patient, prevent cardiac complications of kyperkalaemia
- identify reversible/underlying cause of hyperkalaemia and manage accordingly

Question 2

Hyperkalaemia - History

Answer 2

Would take an A to E approach to initial assessment of this patient, as this is a medical emergency.

History:
- Sx: ascending muscle weakness, palpitations, -LOC/drowsiness
- PMHx: renal failure, diabetes, malignancy
- Meds: Heparin, chemotherapy, ACEi, diuretics
- SNPA

Question 3

Hyperkalaemia - Examination

Answer 3

Exam:
- Start with A to E
- cardio exam
- fluid status

Question 4

Hyperkalaemia - Investigations

Answer 4

Investigations:
Key/diagnostic
- VBG at POC
- ECG

Bedside: Vitals VBG, ECG (serial), urinalysis
Bloods: FBC, UEC, CMP
Imaging: Not indicated initially, only for underlying pathology investigation (renal, malignancy)

Question 5

Hyperkalaemia - Management

Answer 5

This is a medical emergency. Treated emergently. Call superiors for assistance, potentially requires ICU admission

1 - Stabilise cardiac membranes, stop injurious medications (B-Blockers,
- calcium gluconate - administer according to clinical response and
- correct any fluid imbalance

2 - Move K intracellularly
- Bicarb
- insulin-dextrose
- salbutamol

3 - Increase K elimination
- diuretics
- dialysis
- PR resonium (K binding)

optimise management of ESRF
- arrange renal consult
- ICU review depending on stability

Question 6

Hyperkalaemia - ECG changes

Answer 6

ECG changes in hyperkalaemia:

B - Broad QRS complex
Lo - Loss of p waves
P - Peaked T waves
P - Prolonged PR interval
S - Sine wave