Convective Leakage Makes Heparin Locking of Central Venous Catheters Ineffective Within Seconds: Experimental Measurements in a Model Superior Vena Cava.
Convective Leakage Makes Heparin Locking of Central Venous Catheters Ineffective Within Seconds: Experimental Measurements in a Model Superior Vena Cava.
复制标题
对流渗漏使中心静脉导管的肝素锁定在几秒钟内失效：上腔静脉模型中的实验测量。
DOI：
10.1097/mat.0000000000000280
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Aliseda,Alberto
中科院分区：
文献类型：
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作者：
Barbour,MichaelC;McGah,PatrickM;Ng,ChinH;Clark,AliciaM;Gow,KennethW;Aliseda,Alberto
放置在上级腔静脉（SVC）中用于血液透析或化疗的中心静脉导管（CVC）在不使用时常规填充肝素（一种抗凝剂），以保持通畅并防止导管尖端形成血栓。然而，肝素锁定手术使患者面临全身出血的风险，因为已知肝素会从导管泄漏到血流中。我们提供了来自详细的体外实验的证据，这些实验表明肝素泄漏背后的驱动机制是由于导管周围的脉动流引起的对流-扩散运输。这种新的机制是支持实验平面激光诱导荧光（PLIF）和粒子图像测速（PIV）测量的流速和肝素运输从CVC放置在模型SVC内的脉动流回路。结果预测了一个初始的、快速的（< 10 s）、对流占主导地位的阶段，该阶段迅速耗尽近头端区域（导管的侧孔区域）中的肝素浓度。随后是导管腔内缓慢的扩散受限阶段，其中浓度仍然很高，这不足以补充近头端区域中损失的肝素浓度。此处给出的结果与之前24小时泄漏率的体内估计值一致，预测在透析间期的大部分时间内，近头端区域的肝素浓度基本为零，导致肝素锁定程序无效。
Central venous catheters (CVCs), placed in the superior vena cava (SVC) for hemodialysis or chemotherapy, are routinely filled while not in use with heparin, an anticoagulant, to maintain patency and prevent thrombus formation at the catheter tip. The heparin-locking procedure, however, places the patient at risk for systemic bleeding, as heparin is known to leak from the catheter into the blood stream. We provide evidence from detailed in vitro experiments that shows the driving mechanism behind heparin leakage to be convective–diffusive transport due to the pulsatile flow surrounding the catheter. This novel mechanism is supported by experimental planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV) measurements of flow velocity and heparin transport from a CVC placed inside a model SVC inside a pulsatile flow loop. The results predict an initial, fast (< 10 s), convection-dominated phase that rapidly depletes the concentration of heparin in the near-tip region, the region of the catheter with side holes. This is followed by a slow, diffusion-limited phase inside the catheter lumen, where the concentration is still high, that is insufficient at replenishing the lost heparin concentration in the near-tip region. The results presented here, which are consistent with previous in vivo estimates of 24 hour leakage rates, predict that the concentration of heparin in the near-tip region is essentially zero for the majority of the interdialytic phase, rendering the heparin locking procedure ineffective.