Patrick Testerman, M.D., Kumar G. Belani, M.B.B.S., M.S.
麻醉学，明尼苏达大学，明尼阿波利斯市，明尼苏达

简介：在肝脏移植中，静脉-静脉转流（VVB）经常被用于优化血液动力学稳定性，并尽量降低门静脉和下腔静脉交叉钳夹造成的门脉内脏充血[1, 2]。尽管新的外科手术技术能降低静脉-静脉转流的需求，但是在很多情况下它仍然是肝脏移植手术很重要的组成部分。传统的静脉-静脉转流回路会经过腋静脉，但是，这种新技术需要进行手术切除，因此会延长手术时间并增加感染的风险。一项近期的研究报道了VVB 大口径套管插入术（18 Fr聚氨酯导管）的风险[3]。作者报告了因为胸部出血造成的死亡和心血管崩溃事件。为了降低发病率，一些中心已经开始使用名为canulae的装置（8.5 F）实施经皮技术，尽管流量很低，但是整体效果很令人满意[4]。我们进行了一项评估大通量经皮静脉回路流量的体外研究，以决定能用于VVB的最高可用流量。

方法：我们评估了麻醉师在手术中经常使用的导管引入器和透析导管（见表格），这些导管分别连接着1升的生理盐水袋。我们通过将盐水袋悬挂在1米高度形成的标准重力流来评估流量，或者将盐水袋加压到250毫米汞柱。仅利用插管器和Y型转接器的侧孔对Arrow 9Fr MAC双导管进行测试。

结果：结果见表格。Arrow 9Fr MAC导管不通过Y型附着体也能达到最大流量。其次便是Arrow 9Fr导管鞘和带有Y型附着体的 Arrow 9Fr MAC导管。我们通过Y型附着体对12 Fr 和14 Fr 透析导管进行了检测，发现二者均会轻微降低流量。

讨论与结论：在此项研究的评估过程中，麻醉师拥有大量导管方面的专业知识。在安置肺动脉导管或手术失血后的复苏术时普遍使用这些导管。先前的一项研究发现，在VVB中8.5 Fr canula的流量很令人满意。在VVB中，9 Fr 导管应该能提供相同或更高的流量，并且与较大的18 Fr canulae一起，有望能够降低发病率。
 

表：导管检测得出的流量
导管类型	重力流 (导管尖至盐水袋1米高)	耐压系统
Arrow 9Fr 导管鞘 (Arrow International, Reading, PA 19605)	530 ml/min	1110 ml/min
Arrow 9Fr MAC双导管鞘，有Y型侧孔(Arrow International, Reading, PA 19605)	540 ml/min	1110 ml/min
Arrow 9Fr MAC 双导管鞘，无Y型侧孔 (Arrow International, Reading, PA 19605)	550 ml/min	1190 ml/min
Mahurkar 12Fr 24cm 双联透析导管 (Tyco Health Care, Mansfield, MA 02048)	430 ml/min	950 ml/min
Angiodynamics 14 Fr 15cm双联透析导管(Queensbury, NY 12804)	430 ml/min	1060 ml/min

*检测中使用了生理盐水袋。

参考文献：
1. Kaufman, R.D. Am J Anesthesiol, 1995.
2. Sabate, A. Rev Esp Anestesiol Reanim, 1993.
3. Budd, J.M. Liver Transpl, 2001.
4. Oken, A.C. J Cardiothorac Vasc Anesth, 1994.[table1]


The Optimal Superior Vena Cava Canula for Veno-Venous Bypass during Liver Transplantation
Patrick Testerman, M.D., Kumar G. Belani, M.B.B.S., M.S.
Anesthesiology, University of Minnesota, Minneapolis, Minnesota

Introduction: Veno-venous bypass (VVB) is frequently employed during liver transplantation to optimize hemodynamic stability and minimize portal splanchnic engorgement during cross-clamping of the portal vein and inferior vena cava[1, 2]. While newer surgical techniques have reduced the need for veno-venous bypass it still remains an important part of liver transplant in many cases. Traditional return access for the veno-venous bypass circuit has been via the axillary vein however, this technique requires a surgical cut-down approach, increasing operative time and infection risk. A recent review reported on the risk of large bore cannulation (18 Fr polyurethane catheters) for VVB[3]. The authors reported death and cardiovascular collapse due to hemorrhage in the chest. To decrease morbidity, at some centers percutaneous techniques using 8.5 F canulae have been used satisfactorily although with lower achievable flow rates[4]. We conducted an in-vitro study to evaluate flow rates of commercially available percutaneous venous access canulae to determine highest achievable flow rates that may be used for VVB.

Methods: We evaluated commonly used catheter introducers and dialysis catheters used by anesthesia providers during surgery (see Table). These catheters were connected to a 1 liter saline bag and flow rate was assessed either by standard gravity flow at 1 meter height versus flow rate with the saline bag pressurized to 250 mm Hg. The Arrow 9Fr MAC 2 lumen catheter was tested using only the introducer canula and also with the side-port using a 'Y' adaptor.

Results: These are displayed in the Table. The Arrow 9Fr MAC catheter allowed the highest flow rate without the 'Y' port attachment. The next best was the Arrow 9Fr Introducer sheath and the Arrow 9Fr MAC catheter with the 'Y' attachment. The 12 Fr and 14 Fr dialysis catheters were tested with the 'Y' attachment and had slightly lower flow rates.

Discussion and Conclusions: Anesthesia providers have significant expertise in the catheters evaluated in this study. These catheters are commonly employed for placement of a pulmonary artery catheter or for resuscitation during surgical blood loss. A previous study found that the 8.5 Fr canula provided satisfactory flow rates during VVB. The 9 Fr catheters tested should provide same or higher flow rate during VVB and hopefully decrease morbidity reported with the larger 18 Fr canulae.

Table: Flow rates achieved with the catheters tested
Catheter Type	Gravity Flow (1 meter from catheter tip to bag)	Pressurized system
Arrow 9Fr Introducer sheath (Arrow International, Reading, PA 19605)	530 ml/min	1110 ml/min
Arrow 9Fr MAC 2 lumen introducer sheath with Side-port Y (Arrow International, Reading, PA 19605)	540 ml/min	1110 ml/min
Arrow 9Fr MAC 2 lumen introducer sheath without side-port Y (Arrow International, Reading, PA 19605)	550 ml/min	1190 ml/min
Mahurkar 12Fr 24cm dual lumen dialysis catheter (Tyco Health Care, Mansfield, MA 02048)	430 ml/min	950 ml/min
Angiodynamics 14 Fr 15cm dual lumen dialysis catheter (Queensbury, NY 12804)	430 ml/min	1060 ml/min

  *Normal saline was used during testing

References：
1. Kaufman, R.D. Am J Anesthesiol, 1995.
2. Sabate, A. Rev Esp Anestesiol Reanim, 1993.
3. Budd, J.M. Liver Transpl, 2001.
4. Oken, A.C. J Cardiothorac Vasc Anesth, 1994.[table1]

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