Potassium​

​

• Normal daily potassium requirements = 1 - 1.5 mmol/kg/day

• Target: 3.5 - 5 mmol/L

  • Target > 4.0 in ischaemic heart disease, dysrhythmias, intestinal ileus

  • In patients with end-stage renal disease, more judicious use of potassium replacement is appropriate

​

​Hypokalaemia

• ​​Mild hypokalaemia is common in the critically ill cohort​

  • There are multiple reasons, including inadequate daily intake, poor premorbid nutrition, frequent use of loop diuretics, insulin, steroids, etc.​

• Management: ​

  • 10 - 20 mmol KCl IV PRN as per ICU protocol - Chart [K+] target

    • Allows treatment by bedside nursing staff according to specified [K+] target​

  • Oral potassium replacement may be appropriate

    • 1 'slow K' contains 8 mmol KCl​

    • 1 'chlorvescent' contains 14 mmol KCl

 

Hyperkalaemia

• Severity:​

  • Mild​: > 5.5 mmol/L

  • Moderate: > 6.0 mmol/L

  • Severe: > 7.0 mmol/L

• Complications:

  • Conduction abnormalities​

    • Bradycardia​

    • Broad complex sine waves/VF/VT

    • Cardiac Arrest

  • Muscle weakness

  • Metabolic acidosis

• Treatment:

  • Calcium​

    • Calcium stabilises cardiac cell membranes, preventing dysrhythmias - It DOES NOT reduce serum potassium​ levels

    • Indications:

      • ECG changes​

        • PR depression

        • Marked peaked T waves​

        • Widened QRS complexes

      • Moderate to severe hyperkalaemia

        • ECG changes may not appear, even with severe hyperkalaemia; do not wait for ECG changes to treat​

    • Preparations

      • Calcium gluconate​ 10%

        • 2.2 mmol calcium in 10ml vial​

        • May be administered via peripheral access

        • Gluconate requires hepatic metabolism; be cautious in hepatic impairment

      • Calcium chloride 10%

        • 6.8 mmol calcium in 10ml vial​

        • Requires central deliver

          • May be given peripherally in arrest situation​

    • Administer 1 vial of either calcium gluconate or calcium chloride

  • Intracellular potassium shift

    • ​Does not reduce total body potassium​; is a temporising measure

    • Methods:

      • Insulin therapy​

        • First line treatment​

        • Novorapid 10 units IV AND 25-50ml 50% dextrose IV

        • Will reduce serum potassium by 0.5 - 1 mmol/L

        • Effects last 3 - 4 hours

        • Ensure BSL is monitored; risk of hypoglycaemia

      • Salbutamol

        • Second line treatment​

        • Useful in urgent situations in absence of IV access

        • 10 - 20mg nebulised or 8 - 12 puffs with spacer

  • Increase potassium excretion

    • Frusemide​

      • 40 - 80mg IV bolus​

      • Limited by volume state and haemodynamic state

    • Haemofiltration/Dialysis

      • Indicated for refractory or life-threatening hyperkalaemia​

      • Indicated for hyperkalaemia associated with renal impairment

    • Resonium

      • 15 - 30g PO/PR​

      • Slow acting; not suitable for emergency situations

      • Often causes constipation/ileus; should be avoided in critically unwell

    • Sodium bicarbonate solution

      • Preparation:​

        • 100ml 8.4% sodium bicarbonate solution (100 mmol sodium bicarbonate)​

      • Enhances renal potassium excretion, especially in the presence of acidaemia

      • Indications:

        • Hyperkalaemia ​in the presence of metabolic acidosis

        • Hyperkalaemia arrest