Clinical pulmonary infection score reflects oxidative stress and mortality in patients with pneumonia in intensive care unit

Abstract

Introduction: Results of recent trials on antioxidant supplementation yield different outcomes but most of them failed to show survival benefit. Trials with survival benefit emphasised on specific patient population selection and early administration of high-dose antioxidant. Pneumonia is a common disease in the intensive care unit (ICU) with significant mortality. Oxidative damage has been shown as part of the disease mechanism. We conducted this trial to investigate the relationship between clinical pulmonary infection score (CPIS) and antioxidant level in ICU patients with pneumonia to facilitate patient stratification in further trial of antioxidant supplementation. Methods: Patients admitted to ICU suffering from community-acquired pneumonia, nosocomial pneumonia and pre-existing ICU patients developed ventilator-associated pneumonia were recruited. Blood sampling for erythrocyte antioxidant assay, namely catalase, superoxide dismutase and glutathione was performed on day 0 and day 3 of admission. Clinical scores for disease severity (APACHE II score, SOFA score and CPIS) were calculated on day 0 and day 3. Results: A total of 31 patients were recruited. There was no significant correlation between change in erythrocyte antioxidant level and change of CPIS from day 0 to day 3. CPIS 8 point was able to differentiate patient with low erythrocyte catalase and high erythrocyte catalase level (0.50±0.24 U/gHb vs 0.33±0.11 U/gHb; 95% CI, 0.04-0.31; P=0.013). Mean CPIS scores of non-survivor at the time of ICU admission were significantly higher than those of the survivors (8±1 vs 6±2; P=0.01). Conclusion: CPIS can be used as a bedside tool to identify patients with pneumonia at risk of antioxidant depletion and guide subsequent antioxidant therapy. It also prognosticates patients with poor outcome.