目的验证超声波相对血容量检测中消除气泡对回波时差影响的时间和幅度双重甄别技术。方法分别在牛血中注入连续小气泡(1ml/min)和大气泡(每个约5ml)，用超声波相对血容量检测装置测试，采用时间和幅度双重甄别技术获得回波时差数据，与无气泡或无甄别技术情形对照。结果血液中混入气泡时超声回波时差变化显著(t=3.910，P=0.001)，采用双重甄别技术后的结果(13.878±0.112)与无气泡情形(13.910±0.003)对比无显著区别(t=1.279，P=0.216)，增大气泡体积(t=1.092，P=
0.289)或者减半甄别限值(t=1.265，P=0.221)时处理效果无显著区别。结论利用时间和幅度双重甄别技术可有效消除气泡对超声波相对血容量在线检测的影响。

Objectives To validate the time- amplitude screening technology for the elimination of air bubble effect on the on-line mesurement of relative blood volume by ultrasound. Methods Small air bubbles (1ml/min) and big air bubbles (~5ml) were continuously injected into bovine blood samples, and the samples were then tested with a relative blood volume detection device by ultrasound. The time-amplitude screening technology was used to process the obtained data, which were then compared with the data from the blood samples without bubbles and the raw data without processing by the screening technology. Results Significant changes were found in the test results when blood samples were mixed with air bubbles (t=3.91, P= 0.001). However, there was no significant difference between the data from the samples containing air bubbles processed by the time-amplitude screening technology (13.878±0.112) and the data from the samples without air bubbles (13.910±0.003; t=1.279, P=0.216). There was also no significant difference when the bubble volume increased (t=1.092, P=0.289) or the screening limit was halved (t=1.265, P=0.221). Conclusion The air bubble effect on the on-line mesurement of relative blood volume by ultrasound can be effectively eliminated by using the time-amplitude screening technology.