Introducers and protective sleeves may increase thrombogenicity of pulmonary artery catheters

Abstract

Objective: To investigate the cause of clot formation on the surface of non-heparin coated/bonded pulmonary artery catheters. Design: A controlled, unblinded, open-labeled study. Setting: Research laboratory at Tulane School of Medicine, New Orleans, LA. Participants: Rhesus and African Green monkeys. Interventions: Anesthetized monkeys (n = 24) were assigned to one of two groups. The first group (group A) had a pulmonary artery catheter inserted into a femoral vein through a cutdown without passage through an introducer or protective sleeve before insertion. In the second group (group B), the pulmonary artery catheter was passed through an introducer and protective sleeve before insertion in the femoral vein. After the study, the animals were returned to the primate breeding colony. Laboratory values were measured for each animal, and electron micrographs were taken of selected pulmonary artery catheters before and after passage of these catheters through the introducer sheath and/or protective sleeve. Measurements and Main Results: Between the two groups, there was a significant difference in fibrinogen level, but not in hematocrit, prothrombin time, partial thromboplastin time, and platelet count. Clots were visible on 11 of 12 catheters in group B, which was statistically significant ( p < 0.01), compared with only 3 of 12 catheters in group A. The average clot weight was 0.014 ± 0.014 g in group A (range, 0.00 to 0.170 g), which was statistically significant ( p < 0.01), compared with 0.216 < 0.058 g in group B (range, 0.000 to 0.620 g). Electron micrographs taken after catheters were passed through an introducer and/or protective sleeve showed that both significantly altered the surface of the catheter. The surface of the catheter was smooth and homogenous in appearance before insertion. Conversely, both the introducer and protective sleeve produced marked furrowing and a nodular appearance on the catheter surface, as shown by electron micrographs. Conclusion: The data from this study show that the incidence of clot formation and amount of clot formed on the surface of non-heparin-coated pulmonary artery catheters are significantly greater after passage through an introducer and/or protective sleeve. The electron micrographs also show that both introducers and protective sleeves abraded the catheters and were associated with thrombus formation on the catheter. Designing less traumatic valves on these devices is warranted and recommended.