Objective: To establish the incidence and factors associated with hospital-acquired hyponatremia in pediatric surgical patients who received hypotonic saline (sodium 40 mmol/L plus potassium 20 mmol/L) at the rate suggested by the Holliday and Segar’s formula for calculations of maintenance fluids.
Design: Prospective, observational, cohort study.
Setting: Pediatric intensive care unit.
Patients: Eighty-one postoperative patients.
Measurements and Main Results: Incidence and factors associated with hyponatremia (sodium ≤135 mmol/L). Univariate analysis was conducted post surgery at 12 hrs and at 24 hrs. Mean values were compared with independent t test samples. Receiver operating characteristics curve analysis was performed in variables with a p <.05, and relative risks were calculated. Eighty-one patients were included in the study. The incidence of hyponatremia at 12 hrs was 17 (21%) of 81 (95% confidence interval, 3.7–38.3); at 24 hrs, it was was 15 (31%) of 48 (95% confidence interval, 11.4–50.6). Univariate analysis at 12 hrs showed that hyponatremic patients had a higher sodium loss (0.62 mmol/kg/hr vs. 0.34 mmol/kg/hr, p = .0001), a more negative sodium balance (0.39 mmol/kg/hr vs. 0.13 mmol/kg/hr, p < .0001), and a higher diuresis (3.08 mL/kg/hr vs. 2.2 mL/kg/hr, p = .0026); relative risks were 11.55 (95% confidence interval, 2.99–44.63; p = .0004) for a sodium loss >0.5 mmol/kg/hr; 10 (95% confidence interval, 2.55–39.15; p = .0009) for a negative sodium balance >0.3 mmol/kg/hr; and 4.25 (95% confidence interval, 1.99–9.08; p = .0002) for a diuresis >3.4 mL/kg/hr. At 24 hrs, hyponatremic patients were in more positive fluid balance (0.65 mL/kg/hr vs. 0.10 mL/kg/hr, p = .0396); relative risk was 3.25 (95% confidence interval, 1.2–8.77; p = .0201), for a positive fluid balance >0.2 mL/kg/hr.
Conclusions: The incidence of hyponatremia in this population was high and progressive over time. Negative sodium balance in the first 12 postoperative hours and then a positive fluid balance could be associated with the development of postoperative hyponatremia.
Staff Physician (PGE), Pediatric Intensive Care Unit, Hospital Italiano de Buenos Aires, Unidad de Cuidados Intensivos Pedatricos, Buenos Aires, Argentina; Vice-Director (AP), Pediatric Intensive Care Unit, Hospital Italiano de Buenos Aires, Unidad de Cuidados Intensivos Pedatricos, Buenos Aires, Argentina; Director (PGM), Pediatric Intensive Care Unit, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina; Chief (DB), Department of Critical Care Medicine (DB), The Hospital for Sick Children, Toronto, Ontario, Canada; and Professor of Pediatrics and Anesthesia (DB), The Hospital for Sick Children, Toronto, Ontario, Canada.
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