Causes of hyponatraemia in traumatic brain injury patients in intensive care unit settings

Abstract

The aim of this article is to describe the different causes of hyponatraemia in traumatic brain injury (TBI) patients in the intensive care unit (ICU). We carried out a retrospective observational analytical study in the ICU of 442 patients diagnosed with various TBIs, including 150 patients who developed hyponatraemia during their stay in the ICU. A diagnostic algorithm was followed to identify different causes of hyponatraemia. The data were collected using a convenience sampling technique. The results showed that 87% of patients were male and 13% were female. Fourteen per cent were paediatric patients (≤12 years) and the remaining 84% were adults. Sixty per cent of cases had severe head injuries. The predominant age group was 25–36 years (47/150). The incidence of hyponatraemia was 34%. The mean time to onset of hyponatraemia after TBI and ICU admission was 7.74 days. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) was diagnosed in 34 (26%) patients and cerebral salt wasting (CSW) in 32 (21%) patients as a cause of hyponatraemia. Other causes were found in the remaining patients (79/150), mainly dehydration, during weaning and postextubation phase, overuse of fluids, use of hypotonic fluids, overtreatment with desmopressin acetate, postoperative phase, and use of diuretics. Comorbid conditions were found in only 10% of cases; all other patients (90%) were previously healthy. No cases of hyponatraemia as a result of adrenal insufficiency or hypothyroidism were found. In conclusion, SIADH and CSW are still the most common causes of hyponatraemia in TBI patients, but various other causes of hyponatraemia in the setting of the ICU exist.