Objective: To determine serum bleomycin-detectable 'free' iron in patients with septic shock and to relate these findings to both outcome and a marker of free radical damage.
Design: A prospective observational study.
Setting: A nine-bed intensive care unit in a university teaching hospital.
Patients: Sixteen consecutive patients with septic shock, defined as: (1) Clinical evidence of acute infection; (2) hypo- or hyperthermia (< 35.6° or > 38.3 °C); (3) tachypnoea ( > 20 breaths/min or ventilated); (4) tachycardia ( > 90 beats min); (5) shock(systolic pressure < 90 mmHg) or on inotropes. Fourteen patients also had secondary organ dysfunction.
Measurements and results: Bleomycin-detectable iron concentrations were elevated in all patients (37.2 ± 11.0 μmol/l vs 5.1 ± 3.3 μmol/l in healthy subjects, P < 0.0001), but there was no difference between patients who died and those who survived (39.2 ± 9.3 and 36.2 ± 12.3 μmol/l, respectively). Thiobarbituric acid reactive substances (an index of lipid peroxidation) were higher in those who died (3.33 ± 2.29 μmol/l) than in the surviving patients (0.99 ± 0.14 μmol/l, P < 0.01) or healthy subjects (0.92 ± 0.39 μmol/l, P < 0.01). Free iron did not correlate with thiobarbituric acid-reactive substances. However, a significant correlation was found between lipid peroxidation and clinical severity (APACHE II) score (r = 0.54, P < 0.05).
Conclusions: The present study provides evidence of lipid peroxidation in patients who die with septic shock. The data suggest that iron-catalysed hydroxyl radical generation does not form an important contribution to this lipid peroxidation in patients with sepsis.
- Catalytic iron
- Free radicals
- Lipid peroxide