Abstract:

Objective To dynamically observe the clinical symptoms and pathological changes in a rat model of vinorelbine-induced phlebitis via injection into the dorsalis pedis vein. Methods Twenty-eight 11-week-old male SPF-grade SD rats were randomly divided into a model group (n=20) and a control group (n=8). The model group received a single injection of 0.1 mL vinorelbine solution (4 mg/mL) via the right hind limb dorsalis pedis vein, while the control group received an equal volume of normal saline via the same method. The occurrence and grading of phlebitis in both groups were observed and recorded daily. The volume of the injured limb was measured by the drainage method to calculate the swelling rate. The weight-bearing ratio of the injured limb was assessed using a bipedal balance pain meter, and the skin temperature of the injured limb was measured by infrared thermal imaging. These measurements were conducted for 9 consecutive days. Starting from day 1, three rats from the model group were euthanized every other day. A 1-cm segment of the vein extending proximally from the injection site was collected. Pathological changes in the vein tissue were examined by hematoxylin-eosin staining, and ultrastructural changes of the vascular endothelium were observed using scanning electron microscopy. Results Compared to the control group, the injected hindlimb of model rats showed redness and swelling on day 1, with the swelling rate peaking at (81.89±15.75) % on day 3 (P<0.001), then gradually alleviating and decreasing to (15.41±0.33) % by day 9 (P<0.01). Pain was observed in the affected limbs of model rats on day 1 and worsened markedly on day 3, with the weight-bearing ratio decreasing to (36.35±4.91)% (P<0.001). Meanwhile, the skin temperature of the lesion site increased, reaching (36.36±0.40) ℃ on day 5 (P<0.001). Both pain and fever returned to near normal levels by day 9. Phlebitis grading in the model group showed that 75.0% of rats were grade Ⅱ on day 1; grade Ⅲ and Ⅳ each accounted for 37.5% on day 3; from days 5 to 9, most rats exhibited cord-like veins, predominantly grade III. Venous tissue showed peripheral edema and inflammatory cell infiltration on day 1, which gradually progressed to intimal rupture, vessel wall thickening, and even lumen narrowing from day 3 to 9. The venous intima exhibited destruction of tight junctions between endothelial cells and adhesion of blood cells, progressing to roughened, wrinkled, and protruding intimal surfaces. Conclusion The vinorelbine-induced phlebitis of dorsal foot vein in rat model is characterized by local redness, swelling, warmth, and pain from days 3 to 5, which largely resolve by day 9, although cord-like veins can still be observed. With disease progression, venous tissue develops edema, vessel wall thickening, and lumen narrowing. The venous intima shows rupture, roughening, and in some cases, complete loss.

Key words: Phlebitis, Dorsalis pedis vein, Vinorelbine, Rats