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Risk of harm from CPM syndrome following rapid correction of sodium | Signal

Reference number
Issue date28 February 2012

This Signal is about the potential for risk of harm from Central Pontine Myelinolysis (CPM) syndrome following rapid correction of sodium.


A report received by the NPSA reads:

 “Instructed to give bolus of 1.5ml / kg of hypertonic (5%) saline over two hours to correct moderate hyponatraemia in a patient with a recent neurological deterioration... Instruction was misinterpreted by staff nurse and patient was given an infusion of hypertonic (5%) saline at a rate of 1.5ml / kg (100mls ) every hour for a period of 5 hours until the error was noticed and the infusion stopped.”


CPM is brain cell dysfunction caused by the destruction of the layer (myelin sheath) covering nerve cells in the brainstem (Pons) which prevents signals from being properly transmitted in the nerve. A too rapid change in the body's sodium levels is a common cause of this condition and may occur when abnormal blood levels of sodium are being treated.


A search of incident reports to the National Reporting and Learning System (NRLS) between January 2008 and June 2011 identified 15 incidents of CPM. Three incidents were associated with severe harm. These incidents were caused by errors in the strength, volume or rate of administration of sodium chloride (saline) infusion administered to patients.


Healthcare organisations can minimise the risks of CPM by ensuring that:

1)    the risk of harm from CPM, due to blood sodium levels being corrected too rapidly, is included in all relevant treatment protocols for hyponatraemia and hypernatraemia;


2)    it is mandatory to measure blood sodium levels every 2 – 4 hours when correcting blood sodium levels;


3)    protocols for treating abnormal blood sodium levels clearly state a maximum rate of change of blood sodium (mmol) per hour and 24 hour; and


4)    regular monitoring of clinical state, CNS, and fluid balance occurs.  


The Guidelines and Audit Implementation Network (GAIN) (Northern Ireland) issued guidance on Hyponatraemia in adults (on or after 16th birthday) in 2010.


We would like to hear from you – please contact us with anonymised copies of local investigations or information about your initiatives to reduce risks in any of these areas. 


Signals are notifications of key risks emerging from review of serious incidents reported to the NRLS and shared by the NPSA.