Joyner M J, Warner D O, Rehder K
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905.
Anesthesiology. 1992 Feb;76(2):229-35. doi: 10.1097/00000542-199202000-00012.
The authors hypothesized that relaxation of airway smooth muscle by halothane lessens the dependence of airway resistance on lung volume, and that halothane alters the relationship between pulmonary resistance and lung volume by changing both the airway and tissue components of pulmonary resistance. The relationship among airway resistance, tissue resistance, and lung volume was examined in mongrel dogs before and during the administration of halothane, both in airways with reduced smooth muscle tone (after vagotomy) and during moderate increases in smooth muscle tone caused by vagus nerve stimulation (VNS). Resistance were measured at several levels of positive end-expiratory pressure (PEEP, 4-15 cmH2O) using an alveolar capsule technique. Before halothane administration, airway resistance increased at low PEEP; VNS accentuated this increase. Tissue resistance increased at low PEEP only during VNS. Halothane had no significant effect on any resistance before VNS. During VNS, halothane markedly blunted increases in airway resistance and tissue resistance as PEEP decreased. The authors conclude that during stimulation of airway smooth muscle in dogs, halothane attenuates increases in airway resistance and tissue resistance with reductions in lung volume in dogs. Thus, moderate changes in lung volume have little effect on these resistances during halothane anesthesia under these conditions.
作者们推测，氟烷使气道平滑肌松弛，从而减轻气道阻力对肺容积的依赖性，并且氟烷通过改变肺阻力的气道和组织成分来改变肺阻力与肺容积之间的关系。在杂种犬中，分别在气道平滑肌张力降低（迷走神经切断术后）以及迷走神经刺激（VNS）引起平滑肌张力适度增加的情况下，于氟烷给药前及给药期间，研究气道阻力、组织阻力和肺容积之间的关系。使用肺泡囊技术在几个呼气末正压（PEEP，4 - 15 cmH₂O）水平下测量阻力。在氟烷给药前，低PEEP时气道阻力增加；VNS加剧了这种增加。仅在VNS期间，低PEEP时组织阻力增加。在VNS前，氟烷对任何阻力均无显著影响。在VNS期间，随着PEEP降低，氟烷显著减弱气道阻力和组织阻力的增加。作者得出结论，在犬气道平滑肌受到刺激期间，氟烷可减轻犬肺容积降低时气道阻力和组织阻力的增加。因此，在这些条件下，氟烷麻醉期间肺容积的适度变化对这些阻力影响很小。
