O'Donoghue et al studied the impact of hypernatremia acquired in the intensive care unit (ICU) on in-hospital mortality. Acquired hypernatremia can help to identify a patient at risk for in-hospital mortality although it is rarely the cause. The authors are from Royal Brisbane and Women's Hospital in Brisbane, Australia.
Patient selection: admission to the ICU with normal serum sodium (135 to 145 mmol/L)
Exclusions: burns, neurosurgery, hypertonic saline therapy
Risk factors for in-hospital mortality:
(1) acquired hypernatremia in the ICU (> 150 mmol/L, with odds ratio 2)
(2) older age
(3) higher APACHE 2 score on admission (cutoff not given; will use >= 20 in the implementation)
(4) liver failure (odds ratio 2.1)
(5) hematologic malignancy (leukemia or myeloma, odds ratio 3.6)
(6) serum creatinine on ICU admission >= 200 µmol/L (>= 2.26 mg/dL, odds ratio 2.2)
where:
• A patient with an acquired increase of serum sodium in the 145.1 to 150 mmol/L range had an odds ratio of 1.5 for in-hospital mortality)
• Liver failure and renal failure indicate organ failure(s).
• No clear cutoff given for older age. APACHE 2 includes an age component.
The authors also noted that patients admitted for medical diagnoses had a higher mortality than those with surgical diagnoses.
