Experimental evaluation of a new haemostatic material.

Experimental evaluation of a new haemostatic biomaterial *Continenza M.A., **Pajewski L.A., °D'Ascoli R., **Vegliò F. *Dip. Scienze Chirurgiche, **Dip. Chimica, Ing. Chimica e Materiali - Università degli Studi dell'Aquila, ° Baxter Manifacturing S.p.A, Rieti (I) Introduction: The pharmacopoeia offers many local haemostatic agents to stop the bleeding and often for the surgeon is very hard to choice the better one. In this paper a comparison study was performed between four haemostatic biomaterials: a standard "first aid" cotton gauze, a gelatin sponge (Spongostan), a regenerated cellulose gauze (Tabotamp) and an haemostatic sponge newly synthesized (Matemo). Materials and methods: To obtain objective data, two parameters were measured: the Bleeding Time (BT - s), and the Blood Absorbing Rate (BAR - mg/s); both measures were collected in vivo by a rat model with or without heparin pre-treatment. As fixed in the protocol, the ventral wall of each anesthetized animal was shaved, the skin was incised and in the subcutaneous tissue three veins different in size (small, medium and big vein) were selected and cut, applying the cotton gauze on the left side and on the right side the other new biomaterial, in parallel. At the end of this phase, the abdominal wall was open and two lobe of the liver was injured to test the haemostasis time in the organ bleeding. The BT was measured as the time passing from the vein or organ incision till the stop of bleeding due to the application on the site of one of the selected agents. The Blood Mass lost (BM) was determined by weighting all the pre-weighted haemostatic samples, recovered from the injury after the haemostasis, and for each haemostatic agent, was calculated the BAR rate, dividing the obtained BM by the BT value. The BAR value was considered the most important parameter in this experiment, because of it express the capability of each biomaterial to absorb the blood from the hemorrhage site, and consequently, the performance of maintaining very clean the operation field. To statistically evaluate the data, a factorial model was carried out, repeating four times the experiment for each biomaterial. Results: This experimental protocol produced very interesting results. The new haemostatic sponge Metemo revealed the best performance as when compared with Spongostan as when compared with Tabotamp, in normal and in the heparinized animals. With Matemo sponges, the bleeding time significantly decreased and the blood absorption was the fastest between the four selected haemostatic agents, maintaining the operation field very clean. Obviously, the faster hemostasis determined the least BM loss, revealing in this way the better haemostatic function in order to the animal survival and to the surgeon demands. Further experiments are developing to verify the in vivo biodegradation of this new haemostatic agent Matemo.