Intravenous potassium is frequently used to treat severe or symptomatic hypokalaemia. However the National Patient Safety Agency (2002) has identified a risk to patients from errors occurring during the intravenous administration of potassium solutions. These are ampoules or vials of concentrated potassium chloride or potassium phosphate solution. These can be fatal if given inappropriately, causing cardiac arrest.

The Department of Health, (2012) has classified the accidental administration of concentrated potassium chloride solution as a ‘never event’. Therefore, potassium chloride or potassium phosphate ampoules should only be stocked in designated areas for use by specialist staff and readymade potassium infusions should be used wherever possible.

When you prescribe a potassium infusion, you will need to think about the concentration of potassium and the rate of administration and ensure that these are safe for the patient. This will be dependent on how the infusion will be administered.

When potassium infusions are given via a peripheral IV cannula, the maximum concentration is usually 40mmol of potassium per litre. However 80mmol of potassium per litre may be used in fluid restricted patients with a large peripheral cannula. The maximum infusion rate should not usually exceed 10mmol of potassium per hour. However if the patient has continuous ECG monitoring 20mmol of potassium per hour can be used (UCLH 2010). The infusion should also be administered via a volumetric pump to ensure the accuracy of the administration rate.

Concentrations greater than 80mmol of potassium per litre must be given via a central line (UCLH, 2010).This is to reduce the risk of phlebitis. They must be administered via a volumetric pump and continuous ECG monitoring is required. The maximum infusion rate should not usually exceed 20mmol of potassium per hour. Faster rates may occasionally be needed but continuous ECG monitoring is required due to the risk of serious arrhythmias or cardiac arrest.

When a patient is receiving intravenous potassium, the serum potassium and other serum electrolytes and blood glucose should be monitored. The patient should also be monitored for signs of local pain, vein irritation and extravasation, especially at higher concentrations. The patient should also be monitored for ECG changes, paraesthesia, confusion and weakness, especially at higher concentrations and faster administration rates.

For further information on intravenous drug administration, check out the UCL Hospitals Injectable Medicines Administration Guide, the Medusa Injectable Medicines Guide (available online) and local policies and procedures. In addition, did you know that you can obtain a Summary of Product Characteristics (SPC) and Patient Information Leaflet (PIL) for most medicines at https://www.medicines.org.uk/emc/