Khouri Roger K, Khouri Raoul-Emil R, Lujan-Hernandez Jorge R, Khouri Khalil R, Lancerotto Luca, Orgill Dennis P
Division of Plastic Surgery, Brigham and Women's Hospital, Boston, Mass.; University of Michigan Medical School, Ann Arbor, Mich.; Gulliver Preparatory School, Pinecrest, Fla.; College of Engineering, Boston University, Boston, Mass.; Institute of Plastic Reconstructive and Aesthetic Surgery, University of Padova, Padova, Italy; and Harvard Medical School, Boston, Mass.
Plast Reconstr Surg Glob Open. 2014 Oct 7;2(9):e220. doi: 10.1097/GOX.0000000000000183. eCollection 2014 Sep.
Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention.
We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention.
Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The "Microribbon Model" predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our "Fluid Accommodation Model" predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our "External Volume Expansion Effect Model" predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted.
These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories.
脂肪移植目前在整形手术中广泛应用。长期的移植脂肪留存情况可能难以预测。在新生血管形成之前，脂肪移植物必须通过扩散获取氧气，因此氧气输送可能是影响移植物留存的首要变量。
我们研究了同行评审的文献，以确定脂肪移植物及其周围微环境的哪些方面会影响氧气输送，并创建了3个模型，将不同变量与氧气输送和移植物留存联系起来。
我们的模型证实，当注入一个大的、顺应性好且血管丰富的受体部位时，薄的脂肪微条能使氧气传输最大化。“微条模型”预测，在典型的人体中，半径大于0.16厘米的脂肪注射会出现中央坏死区域。我们的“液体容纳模型”预测，一旦移植组织的间质液压力接近9毫米汞柱的临界值，任何额外的液体会大幅增加间质液压力，并减少毛细血管灌注和氧气输送。我们的“外部容积扩张效应模型”预测术前外部容积扩张引起的血管变化的效果，这种变化能使更多体积的脂肪成功移植。
这些模型证实，初始脂肪移植的存活受氧气扩散限制。术前扩张增加了氧气扩散能力，从而允许更多的移植脂肪留存。这些模型为检验当前脂肪移植理论提供了一个科学框架。
