Introduction In-vitro models for simulating surgical procedures is a cost-effective way of creating fail-safe surgical protocols. Insights gained from these models can also aid in testing new medical devices and reduce the use of animal models. Traditional glass- and silicone-based in-vitro models use distilled water with surfactant additives for lubricity. However, a new material, carboxymethyl cellulose (CMC) dissolved in distilled water, can mimic the mechanical and rheological properties of blood. We have shown that CMC fluid out-performs distilled water, glycerol mixtures, and bovine blood, in terms of physiological accuracy.

Methods We tested the density and dynamic viscosity of the following blood analogs: CMC, distilled water, glycerol mixture (22 wt%), bovine blood (Bos taurus). For each material, samples were tested with a 20 mm cylindrical parallel plate head geometry (0.25 ml) attached to a hybrid rheometer (DHR-2, TA Instruments), set at 37°C (human physiological temperature). Three samples of each blood analog were tested and repeated 5 times. A shear rate sweep from 15 to 105 1/s was tested to cover a wide range of physiological blood flow rates.

Results We compared the density and dynamic viscosity of different materials in table 1. Different CMC fluid concentrations and the resulting viscosity ranges are compared to blood with increasing shear rate (figure 1). CMC matches the initial viscosity and undergoes shear-thinning like human blood. Distilled water has a lower viscosity than blood that does not change with shear rate. It was found that CMC (1% wt) is closest to the material properties of human blood flow at the Circle of Willis (CW).

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Abstract E-204 Figure 1 Viscosity v. Shear graph for CMC fluid at different concentrations

Conclusion CMC fluid is a promising tool in investigating blood flow characteristics in a bench-top model. It can mimic accurate physiologically relevant mechanical properties of blood and has the potential of being used as a go-to tool for medical device testing applications. This fluid will be able to minimize friction between synthetic vessels and endovascular devices and enhance the accuracy of simulated surgery models.

Disclosures H. Sodawalla: None. W. Merritt: None. T. Becker: 1; C; NIH STTR Phase I (#1R41NS097069-01A1).