Department of Surgery and Anesthesiology, CHUV, Lausanne, Switzerland.
Department of Musculoskeletal Medicine, CHUV, Lausanne, Switzerland.
Perfusion. 2020 Jul;35(5):393-396. doi: 10.1177/0267659119885514. Epub 2019 Nov 7.
This study was designed to quantify the influence of blood as test medium compared to water in cannula bench performance assessment.
An in vitro circuit was set-up with silicone tubing between two reservoirs. The test medium was pumped from the lower reservoir by centrifugal pump to the upper reservoir. The test-cannula was inserted in a silicone tube connected between the lower reservoir and the centrifugal pump. Flow rate and pump inlet-pressure were measured for wall-less versus thin-wall cannula using a centrifugal pump in a dynamic bench-test for an afterload of 40-60 mmHg using two media: blood 10 g/dL and 5.6 g/dL and water 0 g/dL.
The wall-less cannula showed significantly higher flows rates as compared to the thin-wall cannula (control), with both hemoglobin concentrations and water. Indeed, for a target volume of 200-250 mL of blood (Hg 10 g/dL) in the upper reservoir, the cannula outlet pressure (P) was -14 ± 14 mmHg versus -18 ± 11 mmHg for the wall-less and control respectively; the cannula outlet flow rate (Q) was 3.91 ± 0.41 versus 3.67 ± 0.45 L/min, respectively. At the same target volume but with a Hg of 5.7 g/dL, P was -16 ± 12 mmHg versus -19 ± 12 mmHg and Q was 4 ± 0.1 versus 4 ± 0.4 L/min for the wall-less cannula and control respectively. Likewise, P and Q values with water were -1 mmHg versus -0.67 ± 0.58 mmHg and 4.17 ± 0.45 L/min versus 4.08 ± 0.47 L/min for the wall-less and control respectively.
Walls-less cannula showed 5.6% less pump inlet-pressure differences calculated between blood and water, as compared to that of thin-wall cannula (-21 times). Flow differences were 6% and 10% for the walls-less and thin-wall cannula respectively. We conclude that testing the cannula performance with water is a good scenario and can overestimate the flow by a 10%. However, superiority for wall-less is preserved with both water and blood.
本研究旨在定量评估血作为测试介质与水相比对套管性能的影响。
在两个储液器之间用硅酮管建立体外回路。通过离心泵从下储液器将测试介质泵送到上储液器。测试套管插入连接在下储液器和离心泵之间的硅酮管中。使用离心泵在 40-60mmHg 的后负荷下对无壁和薄壁套管进行动态台架测试，以两种介质（血红蛋白浓度为 10g/dL 和 5.6g/dL 的血以及 0g/dL 的水）测量无壁套管的流量和泵入口压力。
无壁套管的流量明显高于薄壁套管（对照），无论是血红蛋白浓度还是水。实际上，在上储液器中目标体积为 200-250mL 的血液（Hg 10g/dL）时，套管出口压力（P）分别为-14±14mmHg 和-18±11mmHg；套管出口流量（Q）分别为 3.91±0.41L/min 和 3.67±0.45L/min。在相同的目标体积下，但 Hg 为 5.7g/dL 时，P 分别为-16±12mmHg 和-19±12mmHg，Q 分别为 4±0.1L/min 和 4±0.4L/min。同样，水的 P 和 Q 值分别为-1mmHg 和-0.67±0.58mmHg，4.17±0.45L/min 和 4.08±0.47L/min。
与薄壁套管相比，无壁套管的泵入口压力差（计算值）低 5.6%，差异为 21 倍。无壁套管和薄壁套管的流量差异分别为 6%和 10%。我们得出的结论是，用水测试套管性能是一种较好的方案，可能会高估 10%的流量。然而，无壁套管的优势在水和血中都得以保留。
