Chronic Hyponatremia and Brain Structure and Function Before and After Treatment.

RATIONALE & OBJECTIVE: Hyponatremia is the most common electrolyte disorder and is associated with significant morbidity and mortality. This study investigated neurocognitive impairment, brain volume, and alterations in magnetic resonance imaging (MRI)-based measures of cerebral function in patients before and after treatment for hyponatremia. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: Patients with presumed chronic hyponatremia without signs of hypo- or hypervolemia treated in the emergency department of a German tertiary-care hospital. EXPOSURE: Hyponatremia (ie, plasma sodium concentration [Na+]<125mmol/L) before and after treatment leading to [Na+]>130mmol/L. OUTCOMES: Standardized neuropsychological testing (Mini-Mental State Examination, DemTect, Trail Making Test A/B, Beck Depression Inventory, Timed Up and Go) and resting-state MRI were performed before and after treatment of hyponatremia to assess total brain and white and gray matter volumes as well as neuronal activity and its synchronization. ANALYTICAL APPROACH: Changes in outcomes after treatment for hyponatremia assessed using bootstrapped confidence intervals and Cohen d statistic. Associations between parameters were assessed using correlation analyses. RESULTS: During a 3.7-year period, 26 patients were enrolled. Complete data were available for 21 patients. Mean [Na+]s were 118.4mmol/L before treatment and 135.5mmol/L after treatment. Most measures of cognition improved significantly. Comparison of MRI studies showed a decrease in brain tissue volumes, neuronal activity, and synchronization across all gray matter after normalization of [Na+]. Volume effects were particularly prominent in the hippocampus. During hyponatremia, synchronization of neuronal activity was negatively correlated with [Na+] (r=-0.836; 95% CI, -0.979 to-0.446) and cognitive function (Mini-Mental State Examination, r=-0.523; 95% CI, -0.805 to-0.069; DemTect, r=-0.744; 95% CI, -0.951 to-0.385; and Trail Making Test A, r=0.692; 95% CI, 0.255-0.922). LIMITATIONS: Small sample size, insufficient quality of several MRI scans as a result of motion artifact. CONCLUSIONS: Resolution of hyponatremia was associated with improved cognition and reductions in brain volumes and neuronal activity. Impaired cognition during hyponatremia is closely linked to increased neuronal activity rather than to tissue volumes. Furthermore, the hippocampus appears to be particularly susceptible to hyponatremia, exhibiting pronounced changes in tissue volume. PLAIN-LANGUAGE SUMMARY: Hyponatremia is a common clinical problem, and patients often present with neurologic symptoms that are at least partially reversible. This study used neuropsychological testing and magnetic resonance imaging to examine patients during and after correction of hyponatremia. Treatment led to an improvement in patients' cognition as well as a decrease in their brain volumes, spontaneous neuronal activity, and synchronized neuronal activity between remote brain regions. Volume effects were particularly prominent in the hippocampus, an area of the brain that is important for the modulation of memory. During hyponatremia, patients with the lowest sodium concentrations had the highest levels of synchronized neuronal activity and the poorest cognitive test results.

Sodium evolution in hyponatraemia: a mixed effects model analysis of the Hyponatraemia Registry.

OBJECTIVE: Achieving recommended targets of sodium correction is challenging to physicians treating hyponatraemia. Plasma sodium has to be increased effectively, yet overcorrection must be prevented. This is often hampered by a high variability of responses to treatment. Here, we sought to delineate factors influencing sodium evolution. DESIGN: We retrospectively analysed 3460 patients from the multinational Hyponatraemia Registry comprising a wide range of hyponatraemia aetiologies and treatment strategies. METHODS: Multivariable linear mixed effects models were applied to identify predictors of plasma sodium evolution within the first 24 h of treatment. RESULTS: Evolution of sodium levels over time showed a curvilinear pattern with steeper rise at earlier time points. Baseline sodium showed the most pronounced impact with an additional increment of 3.12 mEq/L for every 10 mEq/L initial sodium reduction. With sodium increments of 1.9 mEq/L and 1.4 mEq/L per 24 h, respectively, the entities hypovolaemic and thiazide-associated hyponatraemia were independent factors for sodium evolution. Therapeutic regimens using hypertonic saline (4.6 mEq/L/24 h), tolvaptan (3.4 mEq/L/24 h), or combination therapy (2.6 mEq/L/24 h) were also associated with a significantly larger sodium rise when compared with no active treatment. CONCLUSIONS: Choice and dosing of active hyponatraemia therapy should be adjusted not only according to aetiology but most importantly to pretreatment sodium. Although counterintuitive, less aggressive therapy in more profound hyponatraemia might be safer but yet effective at least in less severe cases.

Higher chance of survival in patients with out-of-hospital cardiac arrest attributed to poisoning.

AIM OF THE STUDY: Description and comparison of cohort characteristics and outcome of adult patients with out-of-hospital cardiac arrest (OHCA) attributed to poisoning (P-OHCA) versus patients with OHCA attributed to other medical causes (NP-OHCA). METHODS: We included all patients who received cardiopulmonary resuscitation after OHCA between January 2011 and December 2020 from German emergency medical services with good data quality in the German Resuscitation Registry. EXCLUSION CRITERIA: patients < 18 years of age or OHCA attributed to trauma, drowning, intracranial bleeding or exsanguination. RESULTS: Patients with P-OHCA (n = 574) were significantly younger compared to NP-OHCA (n = 40,146) (median age of 43 (35-54) years vs. 73 (62-82) years; p < 0.001). Cardiac arrest in P-OHCA patients was significantly less often witnessed by bystanders (41.8 % vs. 66.2 %, p < 0.001). Asystole was the predominant initial rhythm in P-OHCA patients (73.5% vs. 53.7%, p < 0.001) while ventricular fibrillation (VF) and pulseless electrical activity (PEA) were less common (9.2% vs. 25.1% and 16.2 % vs. 20.5%, p < 0.001). P-OHCA had a higher chance of survival with good neurological outcome at hospital discharge (15.2 vs. 8.8 % p < 0.001) and poisoning was an independent protective prognostic factor in multivariate analysis (OR 2.47, 95%-CI [1.71-3.57]). P-OHCA patients with initial PEA survival with good neurological outcome was comparable to initial VF (34.3 % vs. 37.7%). CONCLUSION: Patients in the P-OHCA group had a significantly higher chance of survival with good neurological outcome and PEA as initial rhythm was as favourable as initial VF. Therefore, in P-OHCA patients resuscitation efforts should be extended.