Russell G B, Snider M T, Richard R B, Loomis J L
Milton S. Hershey Medical Center, Penn State University, University Park 16802.
Undersea Biomed Res. 1991 Jan;18(1):37-45.
Venous air embolism occurs with decompression sickness as well as during a wide variety of surgical procedures in hospitalized patients. We developed a canine model to allow documentation and quantitation of pulmonary excretion of intravascular air emboli both in a control air breathing state and during treatment. We utilized 15N2 (a stable, nonradioactive isotope of room air nitrogen, 14N2) as the nitrogen component of venous air emboli (1 ml.kg-1) given to 27 anesthetized mongrel dogs ventilated with room air (tidal volume = 15 ml.kg-1). End-tidal 15N2 was measured and the embolism diagnosed by increased levels in exhaled gases. Exhaled gases were also collected in Douglas bags and the 15N2 recovered was quantitated by a helium dilution technique. Systemic and pulmonary artery pressure changes and quantitation of excreted 15N2 were documented after embolism during a control state with continued room air (21% oxygen) ventilation, and after treatments with either a) 100% oxygen ventilation; b) compression to 2128 mmHg, or 2.8 atm abs, and room air ventilation; or c) a combination of 100% oxygen ventilation and 2.8 atm abs compression. Increased end-tidal 15N2 was characteristic of all emboli, and use of 15N2 allowed accurate measurement of excreted gas during both room air and 100% oxygen ventilation. Embolic gas recoveries were not increased significantly by any of the treatments.
静脉空气栓塞在减压病以及住院患者的各种外科手术过程中都会发生。我们建立了一个犬类模型，用于记录和定量在对照空气呼吸状态以及治疗过程中血管内空气栓子的肺排泄情况。我们将15N2（一种稳定的、非放射性的室内空气氮同位素，14N2）用作给予27只经室内空气通气（潮气量 = 15 ml.kg-1）的麻醉杂种犬的静脉空气栓子（1 ml.kg-1）的氮成分。测量呼气末15N2，并通过呼出气体中水平的升高来诊断栓塞。呼出气体也收集在道格拉斯袋中，回收的15N2通过氦稀释技术进行定量。在栓塞后，记录对照状态下持续室内空气（21%氧气）通气时的全身和肺动脉压力变化以及排泄的15N2的定量情况，以及在以下治疗后：a）100%氧气通气；b）压缩至2128 mmHg，或2.8 atm abs，并进行室内空气通气；或c）100%氧气通气和2.8 atm abs压缩的组合。呼气末15N2升高是所有栓子的特征，并且使用15N2能够在室内空气和100%氧气通气期间准确测量呼出气体。任何一种治疗方法都没有使栓塞气体回收率显著增加。
