title: Circuits with surface modifying additive alter the haemodynamic response to cardiopulmonary bypass.
abstract: OBJECTIVE
  Blood contact with synthetic surfaces during cardiopulmonary bypass (CPB), inevitably results in the activation of a variety of interrelated pathways of inflammation and coagulation that may contribute to postoperative complications in cardiac surgery patients. The objective of this trial was to evaluate clinical events and complement activation related to the use of a novel biomaterial, into which a surface modifying additive had been incorporated into the polymer used to prepare the bypass circuit.
  
  
  METHODS
  A prospective, double-blind trial was carried out with 34 patients randomized to surgery, with either a standard circuit or a circuit treated ('tip to tip') with the surface modifying additive. Variables recorded included perioperative haemodynamics, volume replacement, alpha-agonist and inotrope use. Terminal complement complex (SC5b-9) was measured using an ELISA.
  
  
  RESULTS
  Upon initiation of bypass, there was a decrease in mean arterial pressure (MAP) in the control group, not seen in the test group (P = 0.0005, ANOVA). There was a decrease in the total volume of replacement fluid given intraoperatively in the test group as compared with the control group (total plus prime; control 5.3 +/- 1.2 L, test 4.4 +/- 1.9 L, P = 0.03, Mann-Whitney test). There was a trend to decreased need for inotrope infusion in the test group after CPB (test 1/17, control 6/17, Fisher exact test; P = 0.085). No difference was seen in the generation of terminal complement complex between the groups either during or after CPB.
  
  
  CONCLUSIONS
  The decrease in blood pressure in the control group, upon the initiation of CPB, did not occur in patients undergoing CPB with the circuit prepared with the surface modifying additive. The decrease in blood pressure was likely associated with the increase in total administered fluids intraoperatively (approximately 1 l/patient) and perhaps the trend towards higher use of inotropes in the control patients as opposed to the test patients. These haemodynamic changes did not appear to be related to complement activation early in CPB.
authors.affiliation: University of Ottawa Heart Institute, Ontario, Canada. frubens@heartinst.on.ca
authors.forename: F D
authors.initials: FD
authors.lastname: Rubens
authors.forename: M
authors.initials: M
authors.lastname: Ruel
authors.forename: G
authors.initials: G
authors.lastname: Lavallee
authors.forename: M
authors.initials: M
authors.lastname: Watson
authors.forename: J
authors.initials: J
authors.lastname: Robblee
authors.forename: D
authors.initials: D
authors.lastname: Wozny
authors.forename: H
authors.initials: H
authors.lastname: Nathan
mesh_terms: D002302:Cardiac Output; D002315:Cardiopulmonary Bypass; D020099:Coated Materials, Biocompatible; D003167:Complement Activation; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume
chemical_list: D020099:Coated Materials, Biocompatible