Gastric flow and mixing studied using computer simulation
Gastric flow and mixing studied using computer simulation
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DOI：
10.1098/rspb.2004.2886
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发表时间：
2004-12-22
影响因子：
4.7
通讯作者：
Brasseur, JG
中科院分区：
文献类型：
--
作者：
Pal, A;Indireshkumar, K;Brasseur, JG
进食的人胃显示出规则的蠕动收缩波，其起源于近端胃窦并传播到幽门。胃的高分辨率同步测压和磁共振成像（MRI）研究表明，胃窦收缩波（ACW）活动的主要功能与胃排空无关。然而，在体内进行详细评价是困难的。在这里，我们分析了ACW活动对胃内流体运动，压力和混合的作用与计算机模拟。一个二维的计算机模型的胃开发与“格子玻尔兹曼”数值方法从物理定律，和胃的几何模型从MRI。胃容量的时间变化被指定为与营养液排空的总体生理速率相匹配。模拟预测了两个基本的流体运动：逆行“射流”通过ACW，和ACW之间的循环流动，这两者都有助于混合。一个定义明确的“混合区”，局限于胃窦，创造了ACW，与混合运动增强多个和较窄的ACW。模拟还预测了远端胃窦中收缩诱导的蠕动压力波，与测压测量结果一致，但压力振幅比测压数据低得多，表明测压压力振幅反映了导管与胃壁的直接接触。我们的结论是，ACW是中央胃混合，也可能发挥间接的作用，通过共同腔压力的局部改变胃排空。
The fed human stomach displays regular peristaltic contraction waves that originate in the proximal antrum and propagate to the pylorus. High-resolution concurrent manometry and magnetic resonance imaging (MRI) studies of the stomach suggest a primary function of antral contraction wave (ACW) activity unrelated to gastric emptying. Detailed evaluation is difficult, however, in vivo. Here we analyse the role of ACW activity on intragastric fluid motions, pressure, and mixing with computer simulation. A two-dimensional computer model of the stomach was developed with the 'lattice-Boltzmann' numerical method from the laws of physics, and stomach geometry modelled from MRI. Time changes in gastric volume were specified to match global physiological rates of nutrient liquid emptying. The simulations predicted two basic fluid motions: retrograde 'jets' through ACWs, and circulatory flow between ACWs, both of which contribute to mixing. A well-defined 'zone of mixing', confined to the antrum, was created by the ACWs, with mixing motions enhanced by multiple and narrower ACWs. The simulations also predicted contraction-induced peristaltic pressure waves in the distal antrum consistent with manometric measurements, but with a much lower pressure amplitude than manometric data, indicating that manometric pressure amplitudes reflect direct contact of the catheter with the gastric wall. We conclude that the ACWs are central to gastric mixing, and may also play an indirect role in gastric emptying through local alterations in common cavity pressure.