Pediatric Versus Adult Shear-Induced Hemolysis: Are Age-Related Blood Properties the Main Cause for Differences?

Shear-induced hemolysis remains a major challenge in pediatric mechanical circulatory support (MCS), where hemolysis-related complications occur more frequently than in adults. Despite known hematologic differences between pediatric and adult blood, it is unclear whether pediatric red blood cells (RBCs) are intrinsically more susceptible to mechanical stress than those from adults. This study compared shear-induced hemolysis of pediatric and adult blood under identical conditions and assessed the predictive accuracy of established power-law hemolysis models.

This study investigated hemolysis of blood in 25 samples from 14 children aged 3-11 years. Repeated shear stress experiments were performed in a Couette shearing device by applying homogeneous, semi-sinusoidal shear stresses between 73 and 139 Pa for 20-80 repetitions. Hemolysis was quantified using the Harboe method and corrected for baseline and processing-related hemolysis. Results were compared to previously published adult data acquired using the same apparatus. Pediatric hemolysis was compared to adult results across defined shear-stress ranges, and two established power-law parameter sets were evaluated for predictive accuracy.

Shear-induced hemolysis (IH) was assessed across mean shear stress amplitudes of 73-139 Pa. Across the full stress range, pediatric IH values (0.013%-0.395%) were lower than adult values (0.035%-0.532%). While no differences were observed at lower shear stresses (73-95 Pa and 95-117 Pa), pediatric samples showed a trend toward lower hemolysis at higher shear stresses (117-139 Pa). Of the two evaluated established parameter sets for power-laws from the literature, the parameter set C = 3.458 × 10-6, α = 0.2777 and β = 2.0639 demonstrated the best agreement within our investigated shear stress range.

Within the examined shear range, pediatric RBCs did not display increased sensitivity to mechanical stress compared to adult RBCs. These results suggest that increased hemolysis in pediatric MCS is more likely related to device design and device operating conditions than to an intrinsically higher susceptibility of pediatric blood. Due to the low availability of pediatric blood, adult blood appears suitable for initial hemolysis testing in pediatric device development, although larger pediatric cohorts will be necessary to refine hemolysis prediction models and to investigate additional blood damage mechanisms.