Effect of adding heparin to parenteral nutrition on catheter intraluminal obstruction based on scanning electron microscopy in preterm neonates: A non-inferiority, randomized controlled trial

•Peripherally inserted central catheter (PICC) is crucial in treating preterm neonates.•The effectiveness of heparin for reducing PICC occlusion is controversial.•Scanning electron microscopy is used for first time for judging catheter obstruction.•Adding heparin may be unnecessary for the maintaining of PICC in preterm neonates. This study aimed to assess the need for adding heparin to parenteral nutrition (PN) on reducing catheter intraluminal obstruction based on scanning electron microscopy (SEM) of peripherally inserted central catheter (PICC) in preterm neonates. In this randomized controlled blinded non-inferiority trial, neonates with gestational age < 32 weeks requiring PICC to receive PN were enrolled and randomly divided into two groups. In the heparin group, 0.5 IU/mL heparin was added to PN for continuous infusion through PICC; while in the no-heparin group, there was no heparin added. All catheter tips were collected for SEM of catheter intraluminal obstruction. The primary outcome was the ratio of intraluminal obstructed area at catheter tip calculated by SEM. A non-inferiority margin of 0.1 was chosen. The duration of catheter patency, incidence of catheter-related complications and heparin-related side effects were analyzed. Between June 1, 2021, to May 31, 2022, 91 neonates (gestational age of 28.17±1.77 weeks) were ultimately enrolled. In the intention-to-treat analysis, the average ratio of intraluminal obstructed area at catheter tip indicated by SEM in no-heparin group was 0.313, and 0.362 in the heparin group (95% CIs of the differences was -0.028 to 0.147). The lower bound of the one-side 95% CI was greater than -0.1, indicating non-inferiority. No statistically significant differences existed in the duration of catheter patency, the incidence of catheter-related complications between two groups. PN without heparin was non-inferior to the addition of 0.5 IU/mL heparin to PN during infusion on reducing catheter intraluminal obstruction based on SEM of PICC in preterm neonates. These findings could reduce the unnecessary exposure to heparin in preterm neonates.