gms | German Medical Science

Objective: Hyponatremia is a common electrolyte disorder in neurocritically ill patients and has in the past been found to be associated with increased morbidity and prolonged in-hospital treatment. In the last years, owing in part to the introduction of antidiuretic hormone receptor (ADH) antagonists to the management portfolio of hyponatremia, the topic of sodium disorders has received increasing clinical attention. The present retrospective study was performed to gain an overview of the current incidence and clinical parameters of patients with hyponatremia on a neurosurgical intensive care unit (ICU).

Methods: Retrospective single-center chart analysis of all patients who fulfilled the following criteria: Treatment for more than one day on our ICU between January 1^st 2014 and December 31^st 2015, and a Na⁺ level below 135 mmol/l at least twice and a Na⁺ level of or below 130 mmol/l at least once during ICU stay (n = 82 patients, Na⁺-group). Additionally, 67 patients, who also spent more than one day on the neurosurgical ICU but with normonatremia (Na⁺ >135 and < 145 mmol/l) served as the control group (CG). The groups were compared with respect to age, length of stay on the ICU, number of control cranial computed tomography (CCT) scans performed during inpatient treatment, length of overall hospital stay and mortality. SPSS was used for data analysis. Normally distributed data were compared by t-tests and non-normally distributed data by Mann-Whitney-U tests. Nominal data were analyzed using the χ²-test or Fisher´s exact test if expected frequencies were below five.

Results: There were no differences between groups with regard to sex but patients in the CG were significantly younger (p=0.033) than the patients with hyponatremia. Patients of the Na⁺-group spent significantly more days on the ICU (8.3 ± 7.77 vs. 5.7 ± 7.45, p< 0.001), were hospitalized for an overall longer time (29.6 ± 22.23 vs. 21.4 ± 16.72 days, p = 0.002) and received more cranial computed tomography scans (4.5 ± 3.24 vs. 2.5 ± 2.23, p < 0.001) than the CG. There was no difference between groups in regard to mortality, with 12 (14.6%) cases of death in the Na⁺-group and 6 (9.0%) cases in the CG (p=0.324).

Conclusion: The present study shows that our patients with hyponatremia had prolonged ICU and in-hospital treatment times. Interestingly, they also received cranial imaging significantly more often than patients in the CG which may be due to hyponatremia-related disturbances of consciousness. A stringent focus on optimal sodium correction should be one of the treatment goals for such patients.