Angel M F, Knight K R, Amiss L R, Morgan R F
Division of Plastic Surgery, Johns Hopkins Medical School, Baltimore, MD 21205.
Microsurgery. 1992;13(5):255-7. doi: 10.1002/micr.1920130512.
The first ischemic insult a tissue suffers is primary (1 degree). A second ischemic episode, such as thrombosis after free tissue transfer may be regarded as secondary (2 degrees) ischemia. The current study investigated 2 degrees ischemia in rodent epigastric flaps. Flaps were elevated in 50 Sprague-Dawley rats: group 1 had 5 hours 1 degree venous ischemia induced by placement of microvascular clamps; group 2 was like group 1, except venous continuity was re-established by venous anastomosis after resection of the venous segment previously microclamped; group 3 had 15 minutes of 1 degree ischemia, 24 hr later 5 hr of 2 degrees venous ischemia was induced by placement of microvascular clamps; group 4 was like group 3, except the venous segment was excised. Necrosis was evaluated on postoperative day 7. Both secondary ischemic groups had significantly less flap survival than the corresponding primary ischemic groups (P less than 0.001 for both). Resection of a portion of the vein and subsequent microanastomosis did not reduce flap survival (NS). Secondary venous ischemia of 5-hr duration is poorly tolerated by rodent skin flaps. There was no difference in flap survival in those flaps whose veins were clamped for 5 hr compared to those flaps whose clamped venous segments were resected and re-anastomosed.
组织遭受的首次缺血性损伤为原发性（1级）。第二次缺血事件，如游离组织移植后的血栓形成，可视为继发性（2级）缺血。本研究调查了啮齿动物腹壁皮瓣的2级缺血情况。在50只Sprague-Dawley大鼠中掀起皮瓣：第1组通过放置微血管夹诱导5小时的1级静脉缺血；第2组与第1组相似，不同之处在于在切除先前用微血管夹夹闭的静脉段后，通过静脉吻合重建静脉连续性；第3组有15分钟的1级缺血，24小时后通过放置微血管夹诱导5小时的2级静脉缺血；第4组与第3组相似，不同之处在于切除静脉段。在术后第7天评估坏死情况。两个继发性缺血组的皮瓣存活率均显著低于相应的原发性缺血组（两者P均小于0.001）。切除部分静脉并随后进行微血管吻合并未降低皮瓣存活率（无显著性差异）。啮齿动物皮瓣对持续5小时的继发性静脉缺血耐受性较差。静脉夹闭5小时的皮瓣与夹闭静脉段切除并重新吻合的皮瓣在皮瓣存活率上没有差异。
