Kozian A, Schilling T, Schütze H, Heres F, Hachenberg T, Hedenstierna G
Department of Medical Sciences, Clinical Physiology, Uppsala University, Sweden.
Br J Anaesth. 2009 Apr;102(4):551-60. doi: 10.1093/bja/aep006. Epub 2009 Feb 17.
One-lung ventilation (OLV) exposes the dependent lung to increased mechanical stress which may affect the postoperative course. This study evaluates regional pulmonary gas/tissue distribution in a porcine model of OLV.
Nine anaesthetized and mechanically ventilated (V(T)=10 ml kg(-1), FI(O(2))=0.40, PEEP=5 cm H(2)O) pigs were studied. After lung separation by an endobronchial blocker, lateral thoracotomy and OLV were performed in six pigs. Three animals served as controls. Static end-expiratory and end-inspiratory spiral computed tomography (CT) scans were done before, during, and after OLV and at corresponding times in controls. CT images were analysed by defined regions of interest and summarized voxels were classified by defined lung X-ray density intervals (atelectasis, poorly aerated, normally aerated, and overaerated).
Dependent lungs contained poorly aerated regions and atelectasis with a significant tidal recruitment during conventional two-lung ventilation (TLV) before OLV (expiration vs inspiration: atelectasis 29% vs 14%; poorly aerated 66% vs 44%; normally aerated 4% vs 41% of the dependent lung volume, P<0.05). During OLV (V(T)=10 ml kg(-1)), cyclic recruitment was increased. The density spectrum of the ventilated lung changed from consolidation to aeration (expiration vs inspiration: atelectasis 10% vs 2%; poorly aerated 71% vs 18%; normally aerated 19% vs 79%, P<0.05). After OLV, increased aeration remained with less atelectasis and poorly aerated regions. Lung density distribution in the non-dependent lung of OLV pigs was unaltered after the period of complete lung collapse.
Cyclic tidal recruitment during OLV in pigs was associated with a persistent increase of aeration in the dependent lung.
单肺通气（OLV）会使非通气肺受到更大的机械应力，这可能会影响术后恢复过程。本研究评估了OLV猪模型中的局部肺气体/组织分布情况。
对9头麻醉并机械通气（潮气量[V(T)] = 10 ml/kg，吸入氧浓度[FI(O₂)] = 0.40，呼气末正压[PEEP] = 5 cm H₂O）的猪进行研究。6头猪通过支气管内封堵器进行肺隔离，然后行侧胸壁切开术和OLV。3头动物作为对照。在OLV前、OLV期间、OLV后以及对照动物的相应时间进行静态呼气末和吸气末螺旋计算机断层扫描（CT）。通过定义的感兴趣区域分析CT图像，并将汇总的体素按定义的肺X线密度区间（肺不张、通气不良、通气正常和通气过度）进行分类。
在OLV前的传统双肺通气（TLV）期间，非通气肺存在通气不良区域和肺不张，且有明显的潮式复张（呼气与吸气相比：肺不张占非通气肺体积的29% 对14%；通气不良占66% 对44%；通气正常占4% 对41%，P<0.05）。在OLV期间（V(T) = 10 ml/kg），周期性复张增加。通气肺的密度谱从实变转变为通气良好（呼气与吸气相比：肺不张占10% 对2%；通气不良占71% 对18%；通气正常占19% 对79%，P<0.05）。OLV后，通气改善持续存在，肺不张和通气不良区域减少。在OLV猪的非通气肺完全萎陷期后，其肺密度分布未改变。
猪在OLV期间的周期性潮式复张与非通气肺通气的持续增加有关。
