Correlation of plasmatic sodium determined by the laboratory and that determined by the dialysis machine.

INTRODUCTION: Changes in plasma sodium concentration (pNa, expressed in mEq/L) are common in hemodialysis (HD) patients. Hemodialysis monitors can estimate pNa by using an internal algorithm based on ion dialysance measurements. The present study studies the accuracy of the correlation between the pNa estimated by the dialysis monitor and that measured by the biochemistry laboratory at our center. MATERIAL AND METHODS: A single-centre prospective observational study in patients on a chronic HD program with the 6008 CAREsystem monitor and standard sodium (138mmol/L) and bicarbonate (32mmol/L) prescriptions. Venous blood samples were drawn from each patient before and after each HD session to ensure inter- and intra-individual validity. The pNa was measured in the biochemistry laboratory using indirect potentiometry and simultaneously the estimated pNa by the HD monitor was recorded at the beginning and at the end of the HD session. For statistical analysis, a scatterplot was made, and Spearman's correlation quotient was calculated. In addition, the differences between both methods were represented as Bland-Altman diagrams. RESULTS: The pre-dialysis pNa measured in the laboratory was 137.49±3.3, and that of the monitor, 137.96±2.91, with a correlation with R2 value of 0.683 (p<0.001). The post-dialysis pNa measured in the laboratory was 137.08±2.23, and that of the monitor was 138.87±1.88, with an R2 of 0.442 (p<0.001). On the Bland-Altman plots, the pre-dialysis pNa has a systematic error of 0.49, in favor of the monitor-estimated pNa, with a 95% confidence interval (CI) of (-3.24 to a 4.22). In the post-dialysis pNa, a systematic error of 1.79 with a 95% CI of (-1.64 to 5.22) was obtained. CONCLUSION: The correlation between the pNa estimated by Fresnius 6008 CAREsystem HD monitor and that measured by the laboratory is good, especially pre-dialysis measurements. Further studies should verify the external validity of these results.

Plasma sodium concentration in older patients as an indicator of severity in emergencies: Results from the Emergency Department and Elder Needs-16 study. / Estudio EDEN-16: sodio plasmático determinado a la llegada a urgencias como indicador de gravedad en pacientes ancianos.

OBJECTIVES: To study baseline factors associated with hypo- and hypernatremia in older patients attended in emergency departments (EDs) and explore the association between these dysnatremias and indicators of severity in an emergency. MATERIAL AND METHODS: We included patients attended in 52 Spanish hospital EDs aged 65 years or older during a designated week. All included patients had to have a plasma sodium concentration on record. Patients were distributed in 3 groups according to sodium levels: normal, 135-145 mmol/L; hyponatremia, 135 mmol/L; or hypernatremia > 145 mmol/L. We analyzed associations between sodium concentration and 24 variables (sociodemographic information, measures of comorbidity and baseline functional status, and ongoing treatment for hypo- or hypernatremia). Indicators of the severity in emergencies were need for hospitalization, in-hospital mortality, prolonged ED stay (> 12 hours) in discharged patients, and prolonged hospital stay (> 7 days) in admitted patients. We used restricted cubic spline curves to analyze the associations between sodium concentration and severity indicators, using 140 mmol/L as the reference. RESULTS: A total of 13 368 patients were included. Hyponatremia was diagnosed in 13.5% and hypernatremia in 2.9%. Hyponatremia was associated with age ($ 80 years), hypertension, diabetes mellitus, an active neoplasm, chronic liver disease, dementia, chemotherapy, and needing help to walk. Hypernatremia was associated with needing help to walk and dementia. The percentages of cases with severity indicators were as follows: hospital admission, 40.8%; in-hospital mortality, 4.3%; prolonged ED stay, 15.9%; and prolonged hospital stay, 49.8%. Odds ratios revealed associations between lower sodium concentration cut points in patients with hyponatremia and increasing need for hospitalization (130 mmol/L, 2.24 [IC 95%, 2.00-2.52]; 120 mmol/L, 4.13 [3.08-5.56]; and 110 mmol/L, 7.61 [4.53-12.8]); risk for in-hospital death (130 mmol/L, 3.07 [2.40-3.92]; 120 mmol/L, 6.34 [4.22- 9.53]; and 110 mmol/L, 13.1 [6.53-26.3]); and risk for prolonged ED stay (130 mmol/L, 1.59 [1.30-1.95]; 120 mmol/L, 2.77 [1.69-4.56]; and 110 mmol/L, 4.83 [2.03-11.5]). Higher sodium levels in patients with hypernatremia were associated with increasing need for hospitalization (150 mmol/L, 1.94 [1.61-2.34]; 160 mmol/L, 4.45 [2.88-6.87]; 170 mmol/L, 10.2 [5.1-20.3]; and 180 mmol/L, 23.3 [9.03-60.3]); risk for in-hospital death (150 mmol/L, 2.77 [2.16-3.55]; 160 mmol/L, 6.33 [4.11-9.75]; 170 mmol/L, 14.5 [7.45-28.1]; and 180 mmol/L, 33.1 [13.3-82.3]); and risk for prolonged ED stay (150 mmol/L, 2.03 [1.48-2.79]; 160 mmol/L, 4.23 [2.03-8.84]; 170 mmol/L, 8.83 [2.74-28.4]; and 180 mmol/L, 18.4 [3.69-91.7]). We found no association between either type of dysnatremia and prolonged hospital stay. CONCLUSION: Measurement of sodium plasma concentration in older patients in the ED can identify hypo- and hypernatremia, which are associated with higher risk for hospitalization, death, and prolonged ED stays regardless of the condition that gave rise to the dysnatremia.

OBJETIVO: Estudiar los factores basales asociados a hiponatremia e hipernatremia en pacientes mayores atendidos en urgencias y la relación de estas disnatremias con eventos indicadores de gravedad. METODO: Se incluyeron durante una semana a todos los pacientes atendidos en 52 servicios de urgencias hospitalarios españoles de edad $ 65 años con determinación de sodio plasmático. Se formaron tres grupos: sodio normal (135-145 mmol/L), hiponatremia ( 135 mmol/L) e hipernatremia (> 145 mmol/L). Se investigó la relación de 24 factores sociodemográficos, de comorbilidad, estado funcional basal y tratamiento crónico con hipo e hipernatremia. Como eventos de gravedad se recogieron necesidad de hospitalización, mortalidad intrahospitalaria, estancia prolongada en urgencias (> 12 horas) en dados de alta y hospitalización prolongada (> 7 días) en hospitalizados, y se analizó su relación con la concentración de sodio mediante curvas spline cúbicas restringidas ajustadas, tomando el valor 140 mmol/L como referencia. RESULTADOS: Se incluyeron 13.368 pacientes (13,5% hiponatremia, 2,9% hipernatremia). La hiponatremia se asoció a edad $ 80 años, hipertensión arterial, diabetes mellitus, neoplasia activa, hepatopatía crónica, demencia, tratamiento con quimioterápicos y ayuda para la deambulación, y la hipernatremia a dependencia, necesidad de ayuda para deambular y demencia. La hospitalización fue del 40,8%, la mortalidad intrahospitalaria del 4,3%, la estancia prolongada en urgencias del 15,9% y la hospitalización prolongada del 49,8%. A mayor hiponatremia, mayor necesidad de hospitalización (sodio 130 mmol/L: OR:2,24; IC 95%: 2,00-2,52; 120 mmol/L: 4,13, 3,08-5,56; 110 mmol/L: 7,61, 4,53-12,8), mortalidad intrahospitalaria (130 mmol/L: 3,07, 2,40-3,92; 120 mmol/L: 6,34, 4,22-9,53; 110 mmol/L: 13,1, 6,53-26,3) y estancia prolongada en urgencias (130 mmol/L: 1,59, 1,30-1,95; 120 mmol/L: 2,77, 1,69-4,56; 110 mmol/L: 4,83, 2,03-11,5), y a mayor hipernatremia mayor necesidad de hospitalización (150 mmol/L: 1,94, 1,61-2,34; 160 mmol/L: 4,45, 2,88-6,87; 170 mmol/L: 10,2, 5,1-20,3; 180 mmol/L: 23,3, 9,03-60,3), mortalidad intrahospitalaria (150 mmol/L: 2,77, 2,16-3,55; 160 mmol/L: 6,33, 4,11-9,75; 170 mmol/L: 14,5, 7,45-28,1; 180 mmol/L: 33,1, 13,3-82,3) y estancia prolongada en urgencias (150 mmol/L: 2,03, 1,48-2,79; 160 mmol/L: 4,23, 2,03-8,84; 170 mmol/L: 8,83, 2,74-28,4; 180 mmol/L: 18,4, 3,69-91,7). No hubo asociación entre estas disnatremias y hospitalización prolongada. CONCLUSIONES: El sodio plasmático determinado en urgencias en pacientes mayores permite identificar hiponatremias e hipernatremias, las cuales se asocian a un riesgo incrementado de hospitalización, mortalidad y estancia prolongada en urgencias independientemente de la causa que haya generado la disnatremia.