Saline flushing to prevent circuit clotting during CRRT without anticoagulant: a randomized controlled study

Regional citrate anticoagulation (RCA) is the preferred strategy during continuous renal replacement therapy (CRRT). However, saline flushing is often used when anticoagulants are contraindicated, although its effectiveness remains uncertain. This study evaluated the efficacy of different saline flushing strategies in preventing circuit clotting during anticoagulant-free CRRT in critically ill patients.

This prospective, three-arm randomized controlled trial included critically ill patients initiating CRRT who had contraindications to anticoagulants. Patients were randomized into three groups: 30-minute flush (200 mL every 30 minutes), 2-hour flush (200 mL every 2 hours), or no flush. The primary outcome was circuit lifespan. The secondary outcomes included the delivered CRRT dose, filtration fraction, nurse satisfaction, length of hospital stay, 28-day mortality, and hypotension incidence within 2 hours of CRRT initiation.

Among 144 randomized patients, 117 (81%) completed the trial: 38 in the 30-minute flush group, 37 in the 2-hour flush group, and 42 in the no-flush group. The mean circuit lifespan was shorter in the 30-minute group (31.03 ± 20.26 h) than in the 2-hour (41.96 ± 18.26 h) and no-flush groups (42.10 ± 19.29 h)(p < 0.05). Significant differences were observed among the 30-minute flush, 2-hour flush, and no-flush groups in terms of delivered CRRT dose (89%, 95% vs. 98%, p < 0.001), filtration fraction (16.14%, 14.05% vs. 13.07%, p < 0.001), and nurse satisfaction (32.26, 62.04 vs. 93.93, p < 0.001). The 30-minute flush group had a higher hypotension incidence within 2 hours of CRRT initiation compared to the no-flush group (71.05% vs. 42.85%, p < 0.017, Bonferroni-adjusted). No significant differences were found in the number of clotting-free patients at 72 hours, hospital stay, or 28-day mortality (p > 0.05).

Frequent saline flushing does not appear to effectively prevent circuit clotting and may be associated with increased hypotension, reduced delivered CRRT dose, higher filtration fraction, and lower nurse satisfaction. These findings suggest that saline flushing should be used cautiously in anticoagulant-free CRRT.

Chinese Clinical Trial Registry:ChiCTR2400080111(01/20/2024).