[9] Hyperkalaemia

Question 1

What is classified as hyperkalaemia?

Answer 1

A serum potassium of greater than 5.5mmol/L

Question 2

When is hyperkalaemia usually asymptomatic?

Answer 2

At relatively low levels

Question 3

Why is hyperkalaemia a very important condition to identify and treat early?

Answer 3

Due to cardiac and other complications that can arise

Question 4

What are the causes of hyperkalaemia?

Answer 4

• Oliguric renal failure
• Potassium sparing diuretics
• Rhabdomyolysis
• Metabolic acidosis
• Excess potassium therapy
• Addison’s disease
• Massive blood transfusion
• Burns
• Drugs
• Artefactual result

Question 5

Give an example of a drug that can cause hyperkalaemia?

Answer 5

ACE inhibitors

Question 6

What should be done if a patient is found on testing to be hyperkalaemic but they do not display any signs or symptoms of hyperkalaemia?

Answer 6

The test should be repeated urgently, as it may be artefactual

Question 7

What can cause an artefactual hyperkalaemia result?

Answer 7

• Haemolysis
• Contamination with potassium EDTA in FBC bottles
• Thrombocythaemia
• Delayed analysis

Question 8

What can cause haemolysis leading to an artefactual hyperkalaemia result?

Answer 8

• Difficult venepuncture
• Patient clenching their fist

Question 9

How can thrombocythaemia cause an artefactual hyperkalaemia result?

Answer 9

Because potassium leaks out from platelets during clotting

Question 10

How can delayed analysis lead to an artefactual hyperkalaemia result?

Answer 10

Potassium leaks out of RBCs

Question 11

Below what serum potassium concentration are symptoms rare in hyperkalamia?

Answer 11

Less than 7.0mmol/L

Question 12

What are the signs and symptoms of hyperkalaemia?

Answer 12

• Fast, irregular pulse
• Chest pain
• Weakness
• Palpitations
• Light-headedness
• Paresthesia

Question 13

When should clinical assessment in hyperkalaemia take place?

Answer 13

Needs to be timely, and is often performed simultaneously with treatment

Question 14

What is involved in the clinical assessment of hyperkalaemia?

Answer 14

• Urine output
• Review of potassium intake
• Review of drugs
• Review history for possible causes of renal disease or major tissue destruction
• Fluid status
• Review recent biochemistry results, in particular renal function and potassium levels

Question 15

What sources of potassium intake need to be reviewed in hyperkalaemia?

Answer 15

• IV fluids
• Potassium supplements
• Diet

Question 16

What drugs should be reviewed in hyperkalaemia?

Answer 16

• ACE inhibitors
• Angiotensin II receptor blockers
• Potassium sparing diuretics

Question 17

What should be involved in a fluid status assessment?

Answer 17

Look for signs of dehydration or fluid overload

Question 18

Describe the importance of ECG in hyperkalaemia

Answer 18

The ECG is vital in the assessment of hyperkalaemia, with the findings progressing with increasing serum potassium levels

Question 19

Describe the relationship between serum potassium concentration and ECG

Answer 19

While ECG findings can generally be correlated to serum potassium concentration, potentially life-threatening arrhythmias can occur without warning at almost any level of hyperkalaemia

Question 20

What is considered to be mild hyperkalaemia?

Answer 20

5.5-6.5mmol/L

Question 21

What are the ECG findings in mild hyperkalaemia?

Answer 21

• Tall ‘tented’ T waves seen across the precordial leads
• Prolonged PR segment

Question 22

What is considered to be moderate hyperkalaemia?

Answer 22

6.5-7.5mmol/L

Question 23

What are the ECG findings in moderate hyperkalaemia?

Answer 23

• Decreased or ‘flattened’ P wave
• Prolonged QRS complex

Question 24

What is considered to be severe hyperkalaemia?

Answer 24

>7.5mmol/L

Question 25

What are the ECG findings in severe hyperkalaemia?

Answer 25

* Progressive widening of QRS complex * Axial deviation and bundle branch blocks

Question 26

What may eventually happen to the ECG in hyperkalaemia?

Answer 26

The progressively widened QRS eventually merges with the T wave, forming a sine wave pattern. Subsequent ventricular fibrillation or asystole may then follow

Question 27

When should you seek expert renal advice in hyperkalaemia?

Answer 27

If potassium is \>6.5mmol/L or there are ECG changes, and the patient is oligo/anuric

Question 28

How should hyperkalaemia be managed when potassium is \>6.5mmol/L, or there are ECG changes?

Answer 28

* Monitor cardiac rhythm * Calcium gluconate 10% 10ml undiluted over 5 mins. Repeat at 5 min intervals as needed, until ECG is normal, with a maximum of 3 doses in total * 10 units insulin + glucose 50% 50ml, give into large vein over 30 minutes * Salbutamol 10mg nebuliser * Stop all potassium containing/sparing drugs, and treat hypotension

Question 29

What monitoring should be done when you give a patient 10 units insulin + glucose 50% 50ml?

Answer 29

Monitor BMs after 15 and 30 minutes, then hourly

Question 30

When should you exercise caution in giving patients salbutamol in hyperkalaemia?

Answer 30

In patients with a history of arrhythmias in IHD

Question 31

When should you consider giving sodium bicarbonate in hyperkalaemia?

Answer 31

If pH \<7.2

Question 32

How often should you recheck potassium in hyperkalaemia when potassium is \>6.5mmolL or there are ECG changes?

Answer 32

Every 2 hours

Question 33

When might a patient with hyperkalaemia need dialysis?

Answer 33

If they develop renal failure, or are oligo/anuric

Question 34

How is hyperkalaemia managed when potassium 6.0-6.5mmol/L with no ECG changes?

Answer 34

* Exclude pseudohyperkalaemia * Stop all potassium containing/sparing drugs * Low potassium diet * Ensure adequate hydration, and monitor urine output * Monitor renal function * Remove excess potassium using calcium resonium 15g PO

Question 35

When should you stop calcium resonium?

Answer 35

Consider stopping when \<6.0mmol/L. Stop when \<5.5mmol/L

Question 36

How is hyperkalaemia managed if potassium \<6.0mmol/L and renal function is stable?

Answer 36

No urgent action is required, arrange dietary modification and medication review