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The diagnosis and management of acute hyponatraemia in critical care

13 October 2022
Volume 31 · Issue 18


Nurses working in critical care, consisting of the intensive care and high dependency units, will encounter a broad range of diseases and conditions. Therefore, a comprehensive knowledge and understanding of common presentations is required, especially for advanced clinical practitioners (ACPs). One of the most common electrolyte disturbances seen within these areas is hyponatraemia, affecting around 40% of patients in critical care and 30% of inpatients. It is important that ACPs working in this area are aware of the symptoms and recommended diagnosis and management.

As health care has become increasingly technology driven and demanding, there has been a growing need to develop health professionals who can work at an advanced level. The introduction of advanced clinical practitioners (ACPs) has led to a blended workforce within the medical team. This is particularly important in areas such as critical care. Continuous professional development for practitioners is essential to consolidate learning, maintain competency and further develop clinical examination and decision-making skills. Although hyponatraemia is commonplace, affecting around 40% of patients in critical care and 30% of inpatients (Friedman and Cirulli, 2013), there is a paucity of literature on this subject within nursing journals. Therefore, this clinical review will focus on hyponatraemia, its diagnosis, and treatment, and is particularly aimed at ACPs working in critical care.

The recognised normal range for serum sodium concentration (SNa) in adults is accepted as 135-145 millimoles per litre (mmol/litre). Hyponatraemia is more commonly an excess of total body water rather than sodium deficiency, being defined as an SNa of less than 135 mmol/litre. It is classified into mild (130-134 mmol/litre), moderate (125-129 mmol/litre) or severe hyponatraemia (an SNa below 125 mmol/litre). Severe hyponatraemia is prevalent in 2-3% of patients (Winzeler et al, 2016; National Institute for Health and Care Excellence (NICE), 2020).

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