Department of Material Science & Engineering, University of Michigan, Ann Arbor, USA.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, USA.
J Mater Sci Mater Med. 2021 Apr 23;32(5):51. doi: 10.1007/s10856-021-06524-8.
Intravenous (IV) fluid administration is critical for all patients undergoing care in a hospital setting. In-patient hospital practice, surgeries, and emergency care require functional IVs for fluid replacement and medication administration. Proper placement of IVs is vital to providing medical services. The ease of placement of an IV catheter, however, depends not only on the size of the catheter but also on provider experience and patient demographics such as age, body mass index, hydration status, and medical comorbidities present challenges to successful IV placement. Smaller diameter IV placement can improve success and there are instances where multiple small diameter catheters are placed for patient care when larger bore access is unattainable. Smaller inner-diameter catheters for anesthesia have functional constraints. Ideally, there would be a smaller catheter for placement that could function as a larger catheter for patient care. One solution is the idea of functionally responsive catheters. Here, we evaluated tubular-shaped hydrogels as potential functional catheters that can increase in inner diameter through fluid swelling using cross-linked homopolymers of polyacrylamide, PAM (10-40% w/w), and their copolymers with 0-8% w/w Poly-(Ethylene Glycol)-Diacrylate, PEGDA. For the PAM gels, the water transport mechanism was shown to be concentration-dependent Fickian diffusion, with the less concentrated gels exhibiting increasingly anomalous modes. Increasing the PEGDA content in the network yielded an initial high rate of water uptake, characterized by Case II transport. The swelling kinetics depended strongly on the sample geometry and boundary conditions. Initially, in a submerged swelling, the annulus expands symmetrically in both outward and inward directions (it thickens), reducing the internal diameter by up to 70%. After 1 h, however, the inner diameter increases steadily so that at equilibrium, there is a net (>100%) increase in all the dimensions of the tube. The amount of linear swelling at equilibrium depended only on the polymer volume fraction as made, while the rate of inner diameter expansion depended on the hydrophilicity of the matrix and the kinetics of sorption. This study serves as proof of concept to identify key parameters for the successful design of hydrogel-based catheter devices with expanding inner-diameters for applications in medical care.
静脉（IV）输液对于在医院环境中接受护理的所有患者都至关重要。住院患者的医院治疗、手术和急救护理都需要功能性 IV 来进行液体替代和药物管理。正确放置 IV 至关重要，它是提供医疗服务的基础。然而，IV 导管的放置是否容易不仅取决于导管的大小，还取决于提供者的经验以及患者的人口统计学特征，如年龄、体重指数、水合状态和并存的医疗合并症，这些都给成功的 IV 放置带来了挑战。较小直径的 IV 放置可以提高成功率，在无法获得较大口径通道的情况下，为了患者的护理，有时会放置多个较小直径的导管。用于麻醉的较小内径导管具有功能限制。理想情况下，有一种更小的导管可以用于放置，同时也可以作为更大的导管用于患者护理。一种解决方案是功能响应导管的概念。在这里，我们评估了管状水凝胶作为潜在的功能性导管，它们可以通过交联的聚丙烯酰胺（PAM）均聚物（10-40% w/w）和它们与 0-8% w/w 聚（乙二醇）-二丙烯酸酯（PEGDA）的共聚物，利用流体膨胀增加内径。对于 PAM 凝胶，水传输机制表现为浓度依赖性菲克扩散，浓度较低的凝胶表现出越来越异常的模式。增加网络中的 PEGDA 含量会产生初始高水吸收率，其特征是 II 型传输。溶胀动力学强烈依赖于样品的几何形状和边界条件。最初，在浸没溶胀中，环在向外和向内两个方向上对称膨胀（变厚），将内径减小多达 70%。然而，在 1 小时后，内径会稳定增加，以至于在平衡时，管的所有尺寸都有净（超过 100%）增加。平衡时的线性溶胀量仅取决于制造时的聚合物体积分数，而内径膨胀速率取决于基质的亲水性和吸附动力学。这项研究为成功设计具有扩张内径的基于水凝胶的导管装置提供了概念验证，这些导管可用于医疗保健领域。
