Hyldegaard O, Madsen J
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
Undersea Hyperb Med. 1994 Dec;21(4):413-24.
Our purpose was to examine the behavior of air bubbles in three non-lipid tissues (skeletal muscle, tendon, and the anterior chamber of the eye) during breathing of air, helium-oxygen (heliox, 80:20), or oxygen. Air bubbles were injected into skeletal muscle or tendon in rats after decompression from a 1-h air exposure at 3.5 atm abs (355 kPa) or into the anterior chamber of the rat eye without any previous pressure exposure. The bubbles were studied by photomicroscopy at 1 atm abs (101 kPa) during either air breathing or during air breathing followed by heliox or O2 breathing. Muscle: during air breathing, all bubbles initially increased in size for a period of 55-100 min after decompression and then started to shrink. Both heliox and O2 breathing increased the shrinking rate as compared to air. Bubble size decreased more rapidly during O2 than heliox breathing. Tendon: during air breathing, bubble size decreased at a constant rate; in one bubble the decrease was preceded by a small increase. During heliox breathing most bubbles decreased faster than during breathing of air. O2 breathing caused a short-term increase in bubble size in 4 out of 10 bubbles. Otherwise, the shrinkage rate was increased in six bubbles and uninfluenced in four bubbles during breathing of O2. Rat eye: during air breathing all bubbles shrank in the observation period. When heliox breathing was started, all bubbles transiently grew for 10-35 min, after which they began shrinking faster than during air breathing. When O2 breathing was started, five out of seven bubbles initially grew or stopped shrinking for 5-15 min, after which they decreased in size faster than during both air and heliox breathing. We conclude that breathing of either heliox or O2 will cause air bubbles in aqueous tissues to disappear faster than during breathing of air. Since heliox breathing promoted bubble shrinking in both muscle and tendon, gas exchange was probably not primarily limited by extravascular diffusion in these aqueous tissues. The present experiments suggest that heliox breathing at 1 atm abs may not exacerbate limb bends.
我们的目的是研究在空气、氦氧混合气（80:20 氦氧混合气）或氧气呼吸过程中，三种非脂质组织（骨骼肌、肌腱和眼前房）中气泡的行为。在大鼠从 3.5 绝对大气压（355 千帕）的 1 小时空气暴露减压后，将气泡注入骨骼肌或肌腱，或者在没有任何先前压力暴露的情况下注入大鼠眼前房。在 1 绝对大气压（101 千帕）下，通过光学显微镜对气泡进行研究，观察空气呼吸时以及空气呼吸后接着进行氦氧混合气或氧气呼吸时气泡的情况。肌肉：在空气呼吸过程中，减压后所有气泡最初在 55 - 100 分钟内体积增大，然后开始缩小。与空气呼吸相比，氦氧混合气和氧气呼吸均提高了缩小速率。氧气呼吸时气泡体积减小的速度比氦氧混合气呼吸时更快。肌腱：在空气呼吸过程中，气泡体积以恒定速率减小；在一个气泡中，减小之前有小幅增大。在氦氧混合气呼吸过程中，大多数气泡减小的速度比空气呼吸时更快。氧气呼吸导致 10 个气泡中有 4 个气泡体积短期内增大。除此之外，在氧气呼吸过程中，6 个气泡的缩小速率增加，4 个气泡不受影响。大鼠眼：在空气呼吸过程中，观察期内所有气泡均缩小。开始氦氧混合气呼吸时，所有气泡短暂增大 10 - 35 分钟，之后它们开始比空气呼吸时更快地缩小。开始氧气呼吸时，7 个气泡中有 5 个最初增大或停止缩小 5 - 15 分钟，之后它们体积减小的速度比空气和氦氧混合气呼吸时都更快。我们得出结论，氦氧混合气或氧气呼吸会使含水组织中的气泡比空气呼吸时消失得更快。由于氦氧混合气呼吸促进了肌肉和肌腱中气泡的缩小，气体交换在这些含水组织中可能主要不受血管外扩散的限制。目前的实验表明，1 绝对大气压下的氦氧混合气呼吸可能不会加重减压病。
