Heparinized solution vs. saline solution in the maintenance of arterial catheters:: a double blind randomized clinical trial

Objectives: The objectives were to analyze the effectiveness of heparinized solution vs. saline solution for the maintenance of arterial catheters and to detect changes in the activated partial thromboplastin time (aPTT) and platelet count in the samples extracted from both groups of arterial catheters. Design: Randomized, double blind, placebo-controlled clinical trial. Setting: Intensive Care Unit of a third-level hospital in Terrassa, Barcelona, Spain. Patients: One hundred and thirty-three patients were included in the trial. The selection criteria were: adults, informed consent, not receiving either full-dose anticoagulant or fibrinolytic treatment, and no thrombocytopenia. Interventions: Sixty-five patients received heparinized solution (1 IU/ml) and 68 received saline solution. Measurements: Arterial catheter functionality was compared in the groups every 8 h and at catheter removal. Patency, reliability of arterial pressure, and curve quality were used to evaluate the functionality of the catheters. Blood was drawn, discarding 7.5 ml, from the arterial catheter and from the venouscatheter simultaneously for coagulation tests. Results: The median duration of catheters being in place was 5.1 days (IQR = 8.1) in the heparin group, and 5.4 (IQR = 7.3) in the saline group (p = 0.7). Kaplan-Meier curves showed no differences between groups (p = 0.6). The number of manipulations required to maintain the patency of the arterial catheters was 35% vs. 40% (p = 0.5). The heparin group had a significantly longer aPTT (2.1 +/- 1.3 vs. 1.25 +/- 0.3, p = 0.001). Conclusions: The use of heparinized solution for arterial catheter maintenance doesnot appear to be justified. It did not increase the duration of the catheters, nor did it improve their functionality significantly. On the other hand, heparin Na altered aPTT significantly.