De Troyer André, Leduc Dimitri
Chest Service, Erasme University Hospital, Route de Lennik 808, 1070 Brussels, Belgium.
J Physiol. 2004 Mar 1;555(Pt 2):481-8. doi: 10.1113/jphysiol.2003.057026. Epub 2003 Dec 23.
The coupling between the ribs and the lung in dogs increases with increasing rib number in the cranial part of the rib cage and then decreases markedly in the caudal part. The hypothesis was raised that this non-uniformity is primarily related to differences between the areas of the lung subtended by the different ribs, and in the current study we tested this idea by assessing the effects of passive lung inflation. Thus, by causing a descent of the diaphragm, inflation would expand the area of the lung subtended by the caudal ribs and improve the coupling between these ribs and the lung. The axial displacements of the ribs and the changes in airway opening pressure (DeltaP(ao)) were measured in anaesthetized, pancuronium-treated, supine dogs while loads were applied in the cranial direction to individual rib pairs at functional residual capacity (FRC) and after passive inflation to 10 and 20 cm H(2)O transrespiratory pressure. In agreement with the hypothesis, inflation caused an increase in DeltaP(ao) for ribs 9 and 10. The most prominent alteration, however, was a marked decrease in DeltaP(ao) for ribs 2-8; at 20 cm H(2)O, DeltaP(ao) for these ribs was only 30% of the value at FRC. Additional measurements indicated that this decrease in DeltaP(ao) results partly from the increase in diaphragmatic compliance but mostly from the reduction in outward rib displacement. This alteration in the pattern of rib motion should add to the decrease in muscle length to reduce the lung expanding action of the external intercostal muscles at high lung volumes.
在犬类中，肋骨与肺之间的耦合在胸廓前部随着肋骨数量的增加而增强，然后在后部显著减弱。由此提出一种假设，即这种不均匀性主要与不同肋骨所对应的肺区域差异有关，在本研究中，我们通过评估被动肺充气的影响来验证这一观点。因此，通过使膈肌下降，充气会扩大尾侧肋骨所对应的肺区域，并改善这些肋骨与肺之间的耦合。在麻醉、用泮库溴铵处理、仰卧位的犬类中，测量肋骨的轴向位移和气道开口压力变化（ΔP(ao)），同时在功能残气量（FRC）以及被动充气至10和20 cm H₂O跨呼吸压力后，向单个肋骨对施加头侧方向的负荷。与该假设一致，充气导致第9和第10肋骨的ΔP(ao)增加。然而，最显著的变化是第2 - 8肋骨的ΔP(ao)显著降低；在20 cm H₂O时，这些肋骨的ΔP(ao)仅为FRC时数值的30%。额外的测量表明，ΔP(ao)的这种降低部分是由于膈肌顺应性增加，但主要是由于肋骨向外位移的减少。肋骨运动模式的这种改变应会增加肌肉长度的减少，从而在高肺容积时降低肋间外肌的肺扩张作用。
