硬膜外导管的大小和流速是否影响不同程序化间歇硬膜外注射方式的注射压力：体外研究
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Do Epidural Catheter Size and Flow Rate Affect Bolus Injection Pressure in Different Programmed Intermittent Epidural Bolus Regimens? An In Vitro Study
背景与目的
用于分娩镇痛的最佳程序化间歇硬膜外推注方式仍然未知。一些研究表明硬膜外腔中更好的药物扩散是由于注射压力增加引起的; 然而，缺乏关于使用硬膜外输注泵对不同导管和流速所产生的最大压力的数据。
方 法
我们评估了11种常用硬膜外导管的流速和压力特征，并结合3种不同的输液泵，根据设置的间歇性硬膜外推注方式进行硬膜外输注。在100,250和400m.h-1的流速下测量压力变化，且推注体积为10mL。为了避免重复测量，使用线性混合模型。通过逐步筛选特征，直到模型中仅剩下统计学上具有显著差异的变量。
结 果
我们进行了660次测量。对于不同的流速和导管设计，在推注期间产生的平均最大压力范围为86至863mmHg。流速和导管规格之间的相互作用导致18G，19G和20G导管的压力分别增加1.31,1.65和2.00mmHg，以1mL.h-1增加流速（P <.001）。包括对钢丝增强导管的分析显示，对于18G，19G和20G导管，以1mL.h-1增加流速，压力分别增加1.16,1.76和2.36 mmHg（P <.001）。在某些情况下，它会触发输注泵堵塞警报。
结 论
在各种导管和流速组合中的体外最大压力值中存在显著差异，对于研究中使用的钢丝增强导管压力值更高。最佳的流速和硬膜外导管组合可允许药物以高流速输注而不触发输注泵堵塞警报。
原始文献摘要
Krawczyk P, Piwowar P, Sałapa K, Lonc T, Andres J；Do Epidural Catheter Size and Flow Rate Affect Bolus Injection Pressure in Different Programmed Intermittent Epidural Bolus Regimens? An In Vitro Study；Anesth Analg.2018 Jul 17. doi: 10.1213/ANE.0000000000003650.
BACKGROUND: The optimal programmed intermittent epidural bolus regimen for labor analgesia remains unknown. Some studies indicate that better drug spread in the epidural space results from greater injection pressure; however, there is a lack of data regarding the maximum pressure generated by epidural bolus injection using different catheters and flow rates.
METHODS: We evaluated the flow and pressure characteristics of 11 commonly used epidural catheters combined with 3 different infusion pumps that deliver epidural infusions according to the programmed intermittent epidural bolus regimen. Pressure changes were measured over time at flow rates of 100, 250, and 400 mL・hour−1 and with a bolus volume of 10 mL. To account for repeated measures, linear mixed models were used. Features were selected with a backward stepwise procedure continued until only statistically significant variables were left in the model.
RESULTS: We performed 660 measurements. The mean maximal pressure generated during bolus injection ranged from 86 to 863 mm Hg for different flow rates and catheter designs. The interaction between flow rate and catheter gauge resulted in 1.31, 1.65, and 2.00 mm Hg of pressure increase for 18G, 19G, and 20G catheters, respectively, per 1 mL・hour−1 of increased flow rate (P < .001). Analyses including wire-reinforced catheters revealed a 1.16, 1.76, and 2.36 mm Hg pressure increase for 18G, 19G, and 20G catheters, respectively, per 1 mL・hour−1 of increased flow rate (P < .001). In some cases, it triggered the occlusion pump alarm.
CONCLUSIONS: Significant differences were observed in the in vitro maximum pressure value among the various catheter and flow rate combinations with a higher pressure value for wirereinforced catheters used in the study. The optimal flow rate and epidural catheter combination may allow for delivery of the bolus with high flow rate without triggering the occlusion alarm.
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