Effects of flush solutions on radial artery catheter patency

This randomized, double blind experimental study was designed to test the effects of flush solutions on radial arterial catheter patency. Factors influencing haemostasis, endothelial damage, rate and turbidity of blood flow, and inherent coagulation factors, provide the framework to examine the arterial catheter flush system. The purpose of this study was to compare the effectiveness of two concentrations of heparin, 2 U/mL and 1 U/mL, and one of normal saline in maintaining patency of radial artery catheters. It was hypothesized that when subjects' radial arterial catheters were provided routine catheter care and continuous flushing with 3 .mL/hr of either heparin 2.0 U/mL, heparin 1.0 U/mL, or saline flush solution there would be: (1) no difference in occlusion risk between flush solution groups as indicated by: prothrombin time (PT), partial thromboplastin time (PTT), platelet count, and the presence of clots in the solution flushed through the catheter and/or on the catheter tip after removal; and (2) no difference in frequency of occlusion between flush solutions groups as indicated by removal of the catheter for any of the following reasons: (a) the inability to flush the catheter, (b) the inability to aspirate blood from the catheter, (c) loss of arterial catheter waveform on the monitor. Thirty cardiac surgery patients were randomly assigned to one of three groups. Each group consisted of 10 subjects who received a flush solution containing either heparin 2.0 U/mL, heparin 1.0 U/mL or saline. Hypothesis one could not be supported. Of the coagulation tests, measured two to three times postoperatively, the 1 U/mL group had more normal PT times on admission and significantly higher platelet counts at 24 hours than the saline and 2 U/mL groups. Since the 1 U/mL group also had significantly shorter pump times, these findings may be related to the mechanical actions of the pump, the high concentration of heparin on pump, and the dilutional effect on the coagulation factors. The finding that seems to be most related to the amount of heparin in the flush solution, is that three catheters in the saline group had clots when removed, while there were no clots in the catheters for the other 2 groups. Hypothesis two also could not be supported. Although there were no significant differences in the frequency of difficulty with flushing the catheter, dampened waveform pattern, and complete loss of arterial waveform pattern, the saline group had significantly more difficulties with aspirating blood and more catheters removed because of occlusion. Furthermore, although not statistically different, the saline group had more positional catheters and their catheters were flushed more often. Although the sample was small, the results of this study tend to indicate that heparin continues to be required in the flush solution to maintain arterial catheter patency.Applied Science, Faculty ofNursing, School ofGraduat