Jones H A, Chakrabarti M K, Davies E E, Hughes J M, Sykes M K
Respir Physiol. 1982 Nov;50(2):177-85. doi: 10.1016/0034-5687(82)90016-0.
The mixing efficiency for two gases of different gaseous diffusivity, helium (He) and sulphur hexafluoride (SF6) have been studied in anaesthetised dogs, closed and open chested, with and without the heart beating. Equilibration of He and SF6 was studied during rebreathing at frequency of 0.5 Hz and a tidal volume of either 0.3 or 0.5 L. Circulation and gas exchange were taken over by a complete heart and lung bypass circuit during the periods when the heart was stopped. The number of breaths required to reach 99% equilibration (n99) ranged from 4 to 14 for He and from 6 to 17 for SF6. There was no significant change in mixing efficiency in any situation. Stopping the heart increased the n99 for He by only 0.4 +/- 11% (1 SD) (n = 21). Opening the chest increased n99 by 1.4 +/- 13% with the heart beating and 2.5 +/- 19% with the heart stopped. The n99 for SF6 was 30 +/- 22% higher than that for He with the chest closed with or without the heart beating. This increased to 37% with the chest opened but was not altered by stopping the heart. The findings for the final phase equilibration rate constant were similar. We conclude that the beating action of the heart does not affect gas mixing in the lungs in the tidal breathing range.
在麻醉的开胸和闭胸犬中，研究了两种具有不同气体扩散率的气体——氦气（He）和六氟化硫（SF6）在有或无心跳情况下的混合效率。在频率为0.5Hz、潮气量为0.3L或0.5L的重复呼吸过程中，研究了He和SF6的平衡情况。在心脏停跳期间，由完整的心肺旁路回路接管循环和气体交换。达到99%平衡所需的呼吸次数（n99），He为4至14次，SF6为6至17次。在任何情况下，混合效率均无显著变化。心脏停跳仅使He的n99增加了0.4±11%（1个标准差）（n = 21）。开胸在心脏跳动时使n99增加了1.4±13%，在心脏停跳时增加了2.5±19%。在有或无心跳的闭胸情况下，SF6的n99比He高30±22%。开胸时这一数值增加到37%，但不受心脏停跳的影响。最终阶段平衡速率常数的研究结果相似。我们得出结论，在潮式呼吸范围内，心脏的跳动动作不会影响肺内气体的混合。
