Activity of anticoagulant proteins on the polymer-coated and heparin-coated membranes in an extracorporeal circulation circuit

Abstract

Introduction We performed in vitro experiments using whole human blood without anticoagulants to clarify the activity of anticoagulant proteins on membranes coated with acrylate-copolymer (ACP) with a hydrophilic blood-contacting layer compared to those coated by immobilizing heparin (IHP) in extracorporeal circulation. Methods Whole human blood from healthy volunteers was recirculated in two types of experimental circuits with an ACP-coated reservoir and tubes and an ACP-coated or IHP-coated membrane. To compare the fluctuation of anticoagulant proteins, the circuit pressure at the inlet and outlet of the membrane was measured every 5 min; antithrombin antigen (ATQ), antithrombin activity, protein-C quantitation (PCQ), protein-C activity, protein-S free antigen (PSQ), and protein-S activity were measured at 0, 30, 60, 120, and 180 min in each experiment ( n = 5). Results The time taken to achieve high circuit pressure (> 300 mmHg) at the inlet of the membrane was significantly shorter in the ACP-coated membrane circuit (28 ± 2.7 min) than in the IHP-coated membrane circuit (54 ± 24 min); however, the ATQ, PCQ, and PSQ at 180 min of recirculation were significantly higher in the former than in the latter (all p < .05). Conclusions ACP-coated membranes can prevent the consumption of anticoagulant proteins but cannot delay circuit thrombogenicity compared to IHP-coated membranes. Considering patient care during the post-extracorporeal circulation period, the use of ACP coating, which can preserve anticoagulant protein, is better in extracorporeal circulation circuits.

Platelet volume indices and von Willebrand factor levels in blood exposed to polymer- or heparin-coated membrane oxygenators

“…With respect to the coating types, our prior study using a comparable experimental circuit revealed that an initial drop in platelet counts, indicating a temporary decrease immediately upon the commencement of circulation, was observed in the IHP circuit, thereby affirming the hemocompatibility of IHP. 13 However, the results of VWF in the present study suggest that IHP can inhibit platelet activation more effectively than ACP can. When considering the treatment of patients with ECC, it may be more beneficial to prevent VWF attenuation rather than focusing on the initial drop, as the latter typically normalizes spontaneously.…”

“…Reports on platelet activation in ECC circuits in clinical settings are doubtful because the data obtained from clinical settings are significantly affected by the type or condition of the disease or individual patient requirements. 13 Because this study was performed under appropriate conditions to eliminate confounding factors, it precisely demonstrated platelet activation in blood exposed to the circuit surface of ECC. In fact, this study had several concerns that the blood left from the human body is attenuated and does not work properly, suggesting that the data in this study cannot be directly accepted for clinical settings.…”

“…When considering the treatment of patients with ECC, it may be more beneficial to prevent VWF attenuation rather than focusing on the initial drop, as the latter typically normalizes spontaneously. 13,37 Further validation using diverse data sets and a thorough evaluation are necessary to determine which coating more effectively mitigates platelet activation.…”

“…However, temporary accumulation of platelets tended to occur in the circuit with a heparin-coated membrane. 13 Nonetheless, in that study, because the materials indicating platelet activation were not tested and only platelet counts were measured, the details of platelet activation in ECC were still unclear. Here, we aimed to clarify the platelet activity in blood in contact with the coating surface on the ECC circuit.…”

“…We hypothesized that polymer coating has several advantages in hemocompatibility and examined the differences between heparin and polymer coatings. 12,13 One of these examinations suggested that the time transitions in the reduction of platelet counts in blood circulating through circuits with both heparin- and polymer-coated membrane oxygenators were comparable. However, temporary accumulation of platelets tended to occur in the circuit with a heparin-coated membrane.…”