Effect of insertion and rotational velocity on friction between catheter and tissue
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Abstract
Purpose: An accurate needle or catheter placement is essential for the success of many procedures like regional anesthesia or biopsy taking. The accuracy of the needle or catheter placement could be increased by application of a rotational motion, which reduces the tissue indentation and required insertion force. Materials and methods: A catheter (5F/1.67 mm Pig angiographic, Boston Scientific) was pulled through muscle tissue (pork tenderloin) over a distance of 125 mm in directions parallel or perpendicular to the muscle fibers. Insertion velocities of 1, 10 and 50 mm/s were applied in combination with 0,114 and 572 RPM. The friction force between the tissue and catheter was measured by the use of a force sensor (Futek Lsb200, 2.5 N). In total 576 measurements were obtained using 16 tissue samples. Results: The results show that the fiber orientation has no effect on the amount of friction. Also the insertion velocity on its own has little effect on the steady friction force. However, a higher insertion velocity normally result in higher maximum insertion force. An increased rotational velocity normally results in a reduced maximum. The steady insertion force is reduced when the tangential velocity is higher than the insertion velocity. A larger ratio results in a lower amount of friction. Conclusion: We conclude that friction forces between instrument and tissue can be reduced by application of a rotational. Hence, rotation of needles and catheters might reduce the effect of indentation and tissue movements and therefore increase the precision of needle or catheter placement.