Simple surface sulfonation retards plasticiser migration and impacts upon blood/material contact activation processes

Background. The use of Di-2-ethylhexyl phthalate (DEHP) plasticised polyvinyl chloride (DEHPPPVC) in medical devices persists despite evidence suggesting that DEHP migration can be harmful. Researchers have shown that a simple surface sulfonation process can retard the migration of DEHP, which may reduce the associated inflammatory response. The present study is designed to investigate the effects of surface sulfonation on DEHP migration and blood contact activation using in vitro and rodent models. Methods. The study was carried out in two phases: phase 1, in which the migration rate of DEHP from DEHPPPVC and sulfonated DEHP plasticised PVC (SDEHPPPVC) was measured; phase 2 of the study, in which the materials were incorporated into a rat recirculation biomaterial test model and blood samples taken to assess CD11b expression on neutrophils, IL-6 and Factor XIIa. Results. The initial DEHP concentration washed from the surface after storage was 37.19 ± 1.17 mg/l in the PPVC group and 5.89 ± 0.81 mg/l in the SPPVC group (p<0.0001). The post-wash migration rate was 3.07 ± 0.32 mg/l/hour in the PPVC group compared to 0.46 ± 0.038 mg/l/hour in the SPPVC group (p<0.0001). In phase 2 of the study, CD11b expression increased by 228.9% ± 37% over the test period in the PPVC group compared to 118.3% ± 46% in the SPPVC group (p<0.01). IL-6 levels rose from 3.1 ± 1.4 pg/ml to 263 ± 26 pg/ml in the PPVC group and 2.2 ± 1.6 pg/ml to 161 ± 29 pg/ml in the SPPVC group (p<0.01). Factor XIIa levels rose from 0.22 ± 0.13 g/ml to 3.7 ± 0.32 μg/ml and 0.28 ± 0.09 to 2.71 ± 0.21 μg/ml in the PPVC and SPPVC groups, respectively (p<0.05 at 90 minutes). Conclusions. The simple sulfonation process significantly retards the migration of DEHP and is associated with the moderation of contact activation processes

Leucodepletion during cardiopulmonary bypass reduces blood transfusion and crystalloid requirements

Cardiopulmonary bypass (CPB) is associated with the production of inflammatory responses, which can have significant influence on prognosis. We studied the effects of leucocyte-depletion filters on inflammatory parameters and early postoperative prognosis during coronary revascularization. Twenty patients undergoing elective coronary revascularization were randomly divided into two groups. Ten patients had leucocyte-depletion filters added to the CPB circuit (treatment group) and 10 were used as control cases (control group). Expression of CD11b on neutrophils, and production of myeloperoxidase and lactoferrin, were measured in arterial samples between induction and 3 h postbypass. In addition, clinical parameters were measured during inpatient recovery. CD11b neutrophil expression, and myeloperoxidase and lactoferrin production, were found to be upregulated during CPB and then to decline to preoperative levels by the third postoperative hour. Blood transfusion requirements were reduced in the treatment group, equalling 1.5 ± 1.2 units, compared to 2.7 ± 1.1 units for the control group (p value = 0.034) and so were the volumes of crystalloid infused during the first 24 h postoperatively, equalling 3.9 ± 1.2 l in the treatment group and 3.3 ± 0.7 l in the control group (p value = 0.021). Overall, the application of leucocyte depletion produced an early clinical advantage, underlining the need for an improved understanding and manipulation of the inflammatory response to CPB