Early intensive care unit-acquired hypernatremia in severe sepsis patients receiving 0.9% saline fluid resuscitation

Background Intensive care unit (ICU)-acquired hypernatremia is associated with increased mortality and ascribed to excessive sodium/insufficient free water intakes. We aimed to determine whether the volume of intravenous 0.9% saline fluid resuscitation was associated with hypernatremia in severe sepsis. Methods We retrospectively reviewed the charts of patients admitted to our medical ICU over 1 year with severe sepsis, and recorded all fluid intakes and plasma sodium levels (Na_p) for 5 days along with clinical data. ΔNa_p was defined as the difference between maximal Na _p reached and initial Na_p. Hypernatremia was defined as Na_p > 145 mmoles/l. Results Among 95 patients with severe sepsis, 29 developed hypernatremia within 5 days (31%), reaching a maximum Na _p of 149.1 ± 2.5 mmoles/l on average 3.8 ± 1.5 days after admission. For every 50-ml/kg increase in 0.9% saline intake for the first 48 h, the odds of hypernatremia were 1.61 times larger [confidence interval (CI): 0.98-2.62; P = 0.06] and the mean of ΔNa_p increased by 1.86 mmoles/l (CI: 0.86-2.86; P < 0.001). Compared with non-hypernatremic patients, hypernatremic patients received more 0.9% saline within the first 48 h (111 ± 50 ml/kg vs. 92 ± 42 ml/kg, P < 0.05) and more other fluids from 48 to 96 h (64 ± 38 ml/kg vs. 42 ± 24 ml/kg, P < 0.05). Patients developing hypernatremia had increased length of mechanical ventilation (12.0 ± 12.6 vs. 9.1 ± 7.2 days, P < 0.05) and ICU mortality (38.5% vs. 13%, P < 0.01). Conclusions Early acquired hypernatremia is a frequent complication in severe sepsis patients and is associated with the volume of 0.9% saline received during the first 48 h of admission.