Buckey J C, Goble R L, Blomqvist C G
Pauline and Adolph Weinberger Laboratory for Cardiopulmonary Research, University of Texas Health Science Center, Southwestern Medical School, Dallas 75235-9034.
Med Instrum. 1987 Aug;21(4):238-43.
We have developed a device for continuous direct measurement of human central venous pressure (CVP) during space flight. Normal resting CVP is typically in the range of 5-10 mmHg; in zero gravity, the expected changes are +/- 5 mmHg or less. A 1-mm Hg change in CVP can represent a substantial intravascular fluid shift. The device is small, battery powered, and designed to run for at least 24 hr. Pressure is measured in a saline solution-filled catheter inserted into a central vein. The transducer is placed in the axilla at the level of the catheter tip to offset hydrostatic gradients. A pump and an electronic system mount on the leg. This assembly provides a slow, continuous infusion of heparinized saline solution to maintain the patency of the catheter. The electronic system generates a digital display in mm Hg, an analog output, and a visible and audible alarm for excessive pressure. An air-filled syringe allows for a two-point calibration (zero and a positive pressure generated by measured compression of a known gas volume). A two-failure tolerant system minimizes electric shock hazards. Two latex diaphragms separate the saline solution from the transducer surface, and the electronic system and pump chamber are in separate enclosures. A clear polycarbonate case allows bubbles to be seen. The unit has been tested for pump function, temperature stability, drift, and accuracy. We conclude that this approach provides a unit with sufficient stability, accuracy, and temperature insensitivity for measuring ambulatory CVP for up to 28 hr. The design may be suitable for ambulatory measurement of other intravascular and intracardiac pressures.
我们已经研发出一种用于在太空飞行期间连续直接测量人体中心静脉压（CVP）的设备。正常静息中心静脉压通常在5 - 10 mmHg范围内；在零重力环境下，预期变化为±5 mmHg或更小。中心静脉压1 mmHg的变化可能代表着大量的血管内液体转移。该设备体积小，由电池供电，设计可运行至少24小时。压力通过插入中心静脉的充满盐溶液的导管进行测量。换能器放置在腋窝处导管尖端的水平位置以抵消静水压力梯度。一个泵和一个电子系统安装在腿部。这个组件提供缓慢、持续的肝素化盐溶液输注以维持导管通畅。电子系统以mmHg为单位生成数字显示、模拟输出以及针对过高压力的可视和可听警报。一个充满空气的注射器用于两点校准（零点和由测量已知气体体积压缩产生的正压）。一个双容错系统将电击危险降至最低。两个乳胶隔膜将盐溶液与换能器表面隔开，并且电子系统和泵腔位于单独的外壳中。一个透明的聚碳酸酯外壳可以看到气泡。该装置已针对泵功能、温度稳定性、漂移和准确性进行了测试。我们得出结论，这种方法提供了一个具有足够稳定性、准确性和温度不敏感性的装置，可用于测量动态中心静脉压长达28小时。该设计可能适用于动态测量其他血管内和心内压力。
