Clinical experience with lipopolysaccharide adsorber in cardiac surgery

Background

Endotoxemia is common in cardiac surgery using extracorporeal circulation (ECC) and is correlated to the time of bypass, aortic clamping and postoperative complications. Adsorption of lipopolysaccharide (LPS) has been used in septic patients with positive results.

Materials and methods

The Alteco LPS Adsorber contains polyethylene discs with a specific polypeptide that binds LPS. The priming volume is 80 ml and the recommended blood flow is 100–150 ml/min. Heparin is used for anticoagulation. Fifteen patients scheduled for elective surgery for coronary artery disease and/or valvular surgery were included in the study. Nine patients had the LPS adsorber included in the ECC circuit whereas six patients served as controls with no adsorber. Blood flow through the adsorber was initiated at the time of aortic clamping, adjusted to 150 ml/min, and terminated when weaning from ECC started. Samples for LPS, TNFα, IL-6, and IL-1β were taken before anaesthesia, 10 minutes after aortic clamping, at skin suture and 6 hours after skin suture.

Results

There were no differences between the groups in age, perfusion time and time of aortic clamping (Table 1). The time of adsorber treatment is also shown. The use of the adsorber was uneventful and flow was easily maintained at 100–150 ml/min. LPS was found in two patients, one in each group at skin suture. Both patients had a long clamping time, 113 versus 123 min. Cytokines and complement results are presented in Tables 2 and 3. There were no significant changes in TNFα or IL-1β while IL-6 increased in both groups. Complement factors C3 and C4 decreased in the control group while C1q increased in the adsorber group.

Table 1 Demographics and technical data

Table 2 Concentrations of cytokines

Table 3 Concentrations of complement factors

In vitro studies have shown that the Alteco LPS adsorber can reduce LPS in whole blood. LPS was found in only two patients in our study, probably due to the short duration of perfusion and clamping. Thus the possibility to evaluate the efficacy of the adsorber in this setting was limited. Only IL-6 increased during the study but no difference between the groups was seen. The decrease in C3 and C4 seen in the control group may indicate activation of inflammatory system, more pronounced in the control group.

Conclusion

The adsorber can be used safely in the extracorporeal circulation. Further studies in patients with more pronounced endotoxic response are needed to evaluate the effects of the adsorber on clinical outcome.