Objectives: To confirm early, marked decrease in plasma selenium concentrations in patients admitted to a surgical and medical intensive care unit (ICU), and to study this decrease according to the presence or absence of systemic inflammatory response syndrome (SIRS), sepsis, or direct ischemia-reperfusion.
Design: Prospective, observational study.
Settings: Collaboration between the adult ICU of a 1,100-bed general hospital and a biochemical research laboratory of a university medical center.
Patients: One hundred thirty-four consecutive surgical and medical ICU patients.
Measurements and main results: In the first 31 patients, plasma and urine selenium concentrations were measured by electrothermal atomic absorption spectrometry on admission and once weekly during their ICU stay. These values were compared first with severity scores, criteria for SIRS, sepsis, and organ system failure taken on admission, and then with nosocomial infection, organ system failure during ICU stay, and hospital mortality. An early, low mean plasma selenium concentration was observed in these patients compared with selenium laboratory reference values. Plasma selenium, measured on ICU admission, inversely correlated with Acute Physiology and Chronic Health Evaluation II or Simplified Acute Physiology II scores. Patients with SIRS had lower selenium concentrations than those without SIRS. Mean urine selenium losses were normal in the first 31 patients. Plasma selenium concentration was low in all patients with severe sepsis and septic shock (range 0.20 to 0.72 micromol/L) and in those patients with ischemia-reperfusion from aortic cross-clamping (range 0.34 to 0.68 micromol/L). Despite recommended specific selenium supplementation, plasma selenium concentrations remained low for >2 wks in patients with SIRS. However, there was a slight increase in plasma selenium concentrations in surviving SIRS patients, whereas plasma selenium concentrations decreased in nonsurviving patients. The frequency of ventilator-associated pneumonia, organ system failure, and mortality was three times higher in patients with low plasma selenium concentration at the time of admission (selenium < or =0.70 micromol/L) than for the other patients.
Conclusions: In severely ill ICU patients with SIRS, we observed an early 40% decrease in plasma selenium concentrations, reaching values observed in deleterious nutritional selenium deficiency. This prolonged decrease in selenium concentrations could explain the three-fold increase in morbidity and mortality rates in these patients compared with other ICU patients. The efficacy of selenium treatment in SIRS patients with a high gravity index score or hypoperfusion needs further investigation.