Hyperkalaemia Flashcards
Hyperkalaemia is defined as an elevated serum potassium, greater than … mmol/l (may vary depending on local reference ranges)
Hyperkalaemia is defined as an elevated serum potassium, greater than 5.5 mmol/l (may vary depending on local reference ranges)
Causes
The most common causes of hyperkalaemia in the post-operative patient are:
Post-operative Acute Kidney Injury Repeated blood transfusions Drugs: - Potassium-Sparing Diuretics, including Spironolactone - ACE inhibitors (or ARBs) Excessive potassium treatment
Hyperkalaemia presentation - A patient may commonly be asymptomatic; symptoms are rare in patients with a potassium serum concentration of less than …/l
A patient may commonly be asymptomatic; symptoms are rare in patients with a potassium serum concentration of less than 7.0mmol/l
Any symptoms of hyperkalaemia that may present include paraesthesia, muscle weakness, nausea and vomiting, and palpitations.
Any symptoms of hyperkalaemia that may present include para…, muscle weakness, nausea and vomiting, and …
Any symptoms of hyperkalaemia that may present include paraesthesia, muscle weakness, nausea and vomiting, and palpitations.
The assessment of any patient with hyperkalaemia needs to be timely and is often performed simultaneously with treatment. The initial investigations required are:
Routine bloods, including U&Es, Ca2+ and PO42-, and Mg2+
Venous blood gas (VBG) - A VBG will provide an immediate result of the patient’s potassium levels
ECG - tall tented T waves, prolonged PR - if moderate flattened P wave /prolonged QRS complex - if severe QRS widened, bundle branch blocks
Catheterisation, if necessary (for fluid balance monitoring)
The patients observations and fluid status should be reviewed, as well as their medication (identifying any precipitants of hyperkalaemia).
ECG Changes in Hyperkalaemia
Mild (5.5 – 6.5mmol)
Tall ‘tented’ T waves (seen across the precordial leads)
Prolonged PR segment
Moderate (6.5 – 7.5mmol)
Decreased or ‘flattened’ P wave
Prolonged QRS complex
Severe (> 7.5mmol)
Progressive widening of the QRS complex
Axial deviation and Bundle Branch Blocks
The management of a hyperkalaemic patient can be considered in three parts:
Stabilisation of the myocardium
Reduction of serum potassium
Reduction of total body potassium
Stabilisation of the Myocardium in hyperkalaemia
A stat dose of intravenous Calcium Gluconate or Calcium Chloride (typically 10ml of 10%, dependent on local guidelines) should be started, either when ECG changes are present or in all cases of moderate or severe hyperkalaemia
Continuous cardiac monitoring is required following stabilisation treatment in such cases.
Reduction of Serum Potassium in hyperkalaemia
Variable rate insulin with dextrose infusion should be started (typically 200ml of 20% glucose with 10U of insulin over 30mins, yet varies with local policy), acting to increase cellular uptake of potassium and thus reduce serum concentration.
These measures are only short term, as the potassium will leave the cells within 30-60 minutes, therefore repeated doses may be required. Salbutamol nebulisers may also be additionally added in for further (albeit limited) reduction.
Reduction of Total Body Potassium - hyperkalaemia
Any reversible underlying cause should be identified and appropriately managed*.
Referral to renal physicians may be warranted in cases of severe hyperkalaemia or resistant hyperkalaemia potentially warranting haemodialysis.
*Oral calcium resonium can be used to reduce total body potassium, reabsorbing potassium into the bowel intra-luminally, however this step is complex and specialist input should be sought early.
Key points - hyperkalaemia
Hyperkalaemia is an elevated serum potassium
There are several potential causes of hyperkalaemia, most commonly renal impairment or iatrogenic
Typically asymptomatic, however can cause cardiac instability if not identified and treated appropriately
Management involves stabilisation of the myocardium, reduction of serum potassium, and reduction of total body potassium
