| Popis: |
In vitro hemolysis tests play a very important role in the development of rotary blood pumps such as the axial flow blood pump. A rotary blood pump that has a high normalized index of hemolysis (NIH) will not have good in vivo test results. In other words, a good in vitro hemolysis test result is required before in vivo evaluations can be initiated. Many factors affect in vitro hemolysis test results, such as the effects of the priming volume, the blood-contacting surface area (BCSA) of the test circuit, throttle usage for the test loop resistance, and blood temperature. Each of these parameters was evaluated in the Baylor/NASA axial flow blood pump; the results are described here. Different priming volumes (small; 402 ± 28 ml, large; 674 ± 26 ml) did not affect hemolysis (NIH was 0.0065 ± 0.0049 and 0.0074 0.0055 g/1001, respectively). Different BCSAs (680 and 2000 cm2) of the test circuit did not show significant differences (in NIH 0.0066 ± 0.0034 and 0.0085 ± 0.0057g/1001, respectively). Different throttle systems (clamp with 1/2-inch tubing and clamp with 1/4-inch tubing) did not show a significant difference compared to the corresponding control value (0.0089 ± 0.0049 vs 0.0096 ± 0.0051 g/1001 and 0.0017 ± 0.0003 vs 0.0020 ± 0.0001 g/1001, respectively). At 37°C, the NIH (0.0168 ± 0.0015 g/1001) was significantly (P < 0.05) higher than that at 25°C (0.0065 ± 0.0056 g/1001). According to these test results, the following test conditions were suggested for in vitro hemolysis tests to evaluate rotary blood pumps: One unit of blood (450–500 ml) for the priming volume, small BCSA (approximately 700 cm2) for the test circuit, utilization of a throttle with a clamp with 1/4-inch tubing to obtain the correct test pressure, and blood temperature of 25°C. |
