Latner Thoracic Surgery Research Laboratories, McEwen Centre for Regenerative Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada.
J Heart Lung Transplant. 2012 Oct;31(10):1120-6. doi: 10.1016/j.healun.2012.08.016.
The evaluation of donor lungs by normothermic ex vivo acellular perfusion has improved the safety of organ utilization. However, this strategy requires a critical re-evaluation of the parameters used to assess lungs during ex vivo perfusion compared with those traditionally used to evaluate the donor lung in vivo. Using a porcine model, we studied the physiology of acellular lung perfusion with the aim of improving the accuracy of clinical ex vivo evaluation.
Porcine lungs after 10 hours of brain death and 24 hours of cold ischemia and uninjured control lungs were perfused for 12 hours and then transplanted. PaO2, compliance, airway pressure and pulmonary vascular resistance were measured. Ventilation with 100% nitrogen and addition of red blood cells to the perfusate were used to clarify the physiologic disparities between in vivo blood perfusion and ex vivo acellular perfusion.
During 12 hours of ex vivo perfusion, injured lungs developed edema with decreased compliance and increased airway pressure, but ex vivo PO2 remained stable. After transplantation, injured lungs demonstrated high vascular resistance and poor PaO2. A reduced effect of shunt on ex vivo lung perfusion PO2 was found to be attributable to the linearization of the relationship between oxygen content and PO2, which occurs with acellular perfusate.
Ex vivo PO2 may not be the first indication of lung injury and, taken alone, may be misleading in assessing the ex vivo lung. Thus, evaluation of other physiologic parameters takes on greater importance.
通过常温非细胞体外灌注来评估供体肺，提高了器官利用的安全性。然而，这种策略需要对在非细胞体外灌注期间用于评估肺的参数进行严格的重新评估，与传统上用于评估体内供体肺的参数相比。我们使用猪模型研究了非细胞肺灌注的生理学，旨在提高临床体外评估的准确性。
脑死亡 10 小时和冷缺血 24 小时后的猪肺和未受伤的对照肺进行 12 小时灌注，然后进行移植。测量 PaO2、顺应性、气道压力和肺血管阻力。使用 100%氮气通气和向灌注液中添加红细胞来阐明体内血液灌注和体外非细胞灌注之间的生理差异。
在 12 小时的体外灌注期间，受损的肺发生水肿，顺应性降低，气道压力增加，但体外 PO2 保持稳定。移植后，受损的肺表现出高血管阻力和低 PaO2。发现分流对体外肺灌注 PO2 的影响降低归因于氧含量与 PO2 之间的关系线性化，这发生在非细胞灌注液中。
体外 PO2 可能不是肺损伤的第一个迹象，单独使用时，在评估体外肺时可能会产生误导。因此，评估其他生理参数变得更加重要。
