Plasma antioxidant capacity in critical polytraumatized patients?: methods, severity, and anatomic location

Figure 1 FRAP and ABTS values in plasma of ICU polytrauma patients (n = 73) are significantly different from those of an ageand gender-matched population (CONTROL) (n = 102). Asterisk indicates statistical differences according to Mann-Whitney test (P <0.05). FRAP and ABTS in plasma were measured as described [4] by using, respectively, 2,4,6-tri(2-piridil)-s-triazine, FeCl3, and acetate buffer (300 mM, pH 3.6) and the ABTS radical cation (ABTS + ·) as reagents and by using a Beckman DU-640 spectrophotometer Findings Oxidative stress (OS) has been invoked as a relevant factor in the evolution and outcome of critical care patients. Indeed, antioxidant therapies have been used in critical care patients [1] but with controversial results [2]. This may be explained by assuming OS as a homeostatically regulated parameter and both its excess and its deficit influencing severity progression. Nonetheless, antioxidant agents could mask an OS signaling role, blocking otherwise physiological responses aimed at recovery of homeostasis [3]. We have evaluated plasma total antioxidant capacity (TAC) in traumatized patients in an ICU, and we determined its potential relationship with severity and trauma location. In a prospective observational study of ICU polytraumatized patients (n = 73, mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score of 11 ± 6) of the Hospital Arnau de Vilanova (Lleida, Spain), we measured (in the first 48 hours) plasma TAC by two different methods: the ferric reducing activity/antioxidant power (FRAP) and the capacity for neutralization of the free radical 2,2′-azinobis (3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) as previously described [4]. For control subjects, we used ageand gender-matched volunteers (n = 102). We also evaluated the contribution of antioxidant molecules (uric acid, bilirubin, and albumin) to these values. The protocol was approved by the institutional ethics committee of the Arnau de Vilanova Hospital and followed Declaration of Helsinki guidelines for studies with human individuals. All participants (or their legal representatives) gave their consent for the study.