A comparison of heparinised and non-heparinised normal saline solutions for maintaining the patency of arterial pressure measurement cannulae after heart surgery

BACKGROUND: Heparinized solution (HS) use for the maintenance of arterial cannulas has been associated with coagulation disorders and has not been conclusively shown to confer additional benefits over normal saline (NS) alone. We tested the hypothesis that in adult patients admitted to the cardiac ICU (T0) after cardiac surgery, HS arterial cannulas might be independently associated with increased heparin-induced coagulation disorders and might not be superior to NS arterial cannulas in reducing arterial cannula occlusion. METHODS: In this cohort study, 170 patients who received NS arterial cannulas during the period from T0 to ICU discharge were included in this study from June 1, 2017, to May 1, 2018 (NS group). There were 2930 patients who used HS (2.5 U/ml) arterial cannulas from January 1, 2015, to December 31, 2016 (heparin group). To address indicated biases, we derived a propensity score that predicted the functions of NS and HS in the patency of arterial cannulas. RESULTS: There were 296 patients (148 in the NS group and 148 in the heparin group) with similar risk profiles in the propensity-score matched cohorts. In the propensity-matched patients, the duration of arterial cannulas (P = 0.4) and arterial cannula occlusion (P = 0.5) showed no differences between the NS and heparin groups. However, the heparin group had a significantly increased activated clotting time (P < 0.05), activated partial thromboplastin time (P = 0.01) and allogeneic red blood cell utilization (3.4% vs 10.8%, P < 0.05). Compared with the NS group, the heparin group had more drainage from chest tubes from T0 to T48 (10.6 ± 9.4 ml/kg vs 13.0 ± 7.22 ml/kg, P < 0.05) and had more allogeneic red blood cells transfused (0.1 ± 0.4 U vs 0.4 ± 1.1 U, P < 0.05). CONCLUSION: Based on the results of our study, the addition of heparin to normal saline for flushing arterial pressure monitoring cannulae did not reduce the incidence of catheter thrombosis and result in a very small but statically significant in increase in activated clotting time and activated partial thromboplastin time.