Normal saline to dilute parenteral drugs and to keep catheters open is a major and preventable source of hypernatremia acquired in the intensive care unit

PurposeWe wanted to identify modifiable risk factors for intensive care unit (ICU)–acquired hypernatremia.Materials and MethodsWe retrospectively studied sodium and fluid loads and balances up to 7 days prior to the development of hypernatremia (first serum sodium concentration, [Na+], > 150 mmol/L; H) vs control (maximum [Na+] ≤ 150 mmol/L; N), in consecutive patients admitted into the ICU with a normal serum sodium (< 145 mmol/L) and without cerebral disease, within a period of 8 months.ResultsThere were 57 H and 150 N patients. Severity of disease and organ failure was greater, and length of stay and mechanical ventilation in the ICU were longer in H (P < .001), with a mortality rate of 28% vs 16% in N (P = .002). Sodium input was higher in H than in N, particularly from 0.9% saline to dissolve drugs for infusion and to keep catheters open during the week prior to the first day of hypernatremia (P < .001). Fluid balances were positive and did not differ from N on most days in the presence of slightly higher plasma creatinine and more frequent administration of furosemide, at higher doses, in H than in N.ConclusionsHigh sodium input by 0.9% saline used to dilute drugs and keep catheters open is a modifiable risk factor for ICU-acquired H. Dissolving drugs in dextrose 5% may partially prevent potentially harmful sodium overloading and H.