Impact of R/NIR irradiation of blood on selected hemostatic parameters during and after cardiopulmonary bypass in pigs

Cardiopulmonary bypass (CPB) is associated with significant hemostatic disturbances. Red/near-infrared (R/NIR) light, also known as low-level light therapy (LLLT), may attenuate these effects. This study investigated the impact of R/NIR irradiation on selected hemostatic parameters in pigs subjected to CPB. Twenty-four pigs underwent 1-hour CPB followed by 23 h of observation. In the LLLT group, blood was irradiated with R/NIR light. Platelet count (PLT), platelet-large cell ratio (P-LCR), CD41/CD61 expression, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration, and coagulation factors II–XII were assessed. A two-way repeated-measures analysis of variance (RM-ANOVA) and Tukey’s HSD post hoc test were used. The significance level was set at α = 0.05. CPB induced transient hemostatic changes in both groups. PLT initially decreased, with a more pronounced reduction in the control group, followed by a temporary increase. P-LCR remained below the reference interval throughout the study in the LLLT group. CD41/CD61 expression increased after CPB in the control group but decreased in the LLLT group. CPB markedly prolonged PT and aPTT, particularly at T0.5, and temporarily reduced fibrinogen concentration, which subsequently increased throughout the observation period. The activities of factors II, V, VII, and X decreased after CPB, although without statistical significance. More pronounced and statistically significant reductions were observed for factors VIII, IX, XI, and XII. Their activities partially recovered after CPB; however, the LLLT group showed more prolonged fluctuations and generally lower values. Significant differences between groups were observed for factors IX and XI. R/NIR irradiation exerted a modulatory, though non-uniform, effect on hemostasis. It appeared to help maintain PLT and CD41/CD61 expression closer to baseline levels. The persistently lower P-LCR in the LLLT group may be potentially beneficial, as larger platelets have been associated with increased thrombotic risk. R/NIR irradiation had limited effects on PT, aPTT, and extrinsic pathway factors, while intrinsic pathway factors showed more variable responses and tended to remain closer to the reference interval.