Serum potassium and sodium levels after subarachnoid haemorrhage.

BACKGROUND: Many studies have demonstrated that subarachnoid haemorrhage (SAH) is associated with hyponatraemia but associations with potassium levels are less well studied. There is a clear physiological link between sodium and potassium and abnormal potassium levels that can lead to dangerous outcomes. The purpose of the present study is to define changes in levels of both these cations that occur in standardised salt management of SAH.

METHOD: 114 records of patients admitted between 2 January 2011 and 27 December 2011 with SAH at a single institution were obtained retrospectively. Sodium and potassium values were recorded for 14 days post-SAH from the earliest electrolyte measurements of the day for each patient where available. Patients were identified from the Newcastle SAH database. Fluid management was standardised. Descriptive and non-parametric statistics were used.

RESULTS: The most common electrolyte imbalance was hypokalaemia. Patients were equally as likely to develop more severe hypokalaemia as they were to develop more severe hyponatraemia. Both imply that low potassium is of as much relevance as low sodium post-SAH. Individually there was no significant association between either sodium or potassium imbalance and WFNS grade.

CONCLUSIONS: Low K + is common with current management of a SAH at the Royal Victoria Infirmary.