FLOW VISUALIZATION OF JET VENTILATION IN NEONATAL AIRWAY

新生儿气道喷射通气的流量可视化

• 批准号: 3346227
• 负责人: PETER W SCHERER
• 金额: $ 24.99万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-02-01 至 1989-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3346227
• 关键词: biomedical equipment safety; cinematography; high frequency ventilation; image processing; mathematical model; mechanical stress; model design /development; newborn human (0-6 weeks); physical model; respiratory airway pressure; respiratory gas level; respiratory gas transport; respiratory system; trachea

In infants, conventional ventilatory assistance often leads to pneumothorax since neonatal lungs are more subject to barotrauma than adult lungs. Because of relatively lower airway pressures in comparison to conventional mechanical ventilation, high frequency jet ventilation (HFJV) has been suggested as one method of assisting this patient population. Unfortunately, HFJV has been reported to lead to new traumatic effects including endothelial erosion due to the high velocity jet impinging on the tracheal endothelial surface, and gradual deterioration in overall gas exchange efficiency. Also, results obtained using HFJV in neonates have been difficult to compare due to the wide range of jet design and operation parameters employed by different clinical groups. Central to all of these problems is a lack of a clear understanding of the physical mechanisms of operation of HFJV in neonates. In order to obtain some of this understanding, research is proposed to investigate the hypothesis that jet nozzle design and location exert a major influence on the overall efficiency of gas exchange and tracheal wall shear rates in high frequency jet ventilation (HFJV) in neonates. We propose to test this hypothesis by using the experimental technique of liquid-bead flow visualization in physical scale models of the neonatal bronchial tree. Flow visualization will be achieved by taking conventional and high speed motion pictures of the oscillating liquid flow produced by the jet operating in the models. The liquid-bead flow in the physical models is made similar to the gas flow occurring during HFJV in neonatal lungs by use of the fluid mechanical principle of dynamic and geometrical similarity. The motion picture frames taken of the flow will be developed and analyzed using an image analyzer. By this analysis we will determine the tidal volume actually injected by the jet; the shearing force exerted by the jet on the tracheal wall; and the overall efficiency of the convective airway gas exchange process for a given set of parameters of jet design, operation and location. Pressures at various locations within the liquid-filled models will also be measured simultaneously and used to predict the corresponding gas pressures in the neonatal airways. The principle investigators have developed the technique of liquid-bead flow visualization in bronchial airway models and have applied it with considerable success to the case of normal respiration and high frequency-piston oscillation ventilation.

在婴儿中，常规的呼吸机辅助常常会导致气胸。 因为新生儿的肺比成人的肺更容易受到气压伤。 因为与常规的相比，呼吸道压力相对较低 机械通风，高频喷射通风(HFJV)已被 建议作为帮助这一患者群体的一种方法。 不幸的是，据报道，HFJV会导致新的创伤效应。 包括高速喷流撞击血管内皮细胞造成的侵蚀 气管内皮细胞表面，整体气体逐渐恶化 交换效率。此外，在新生儿中使用HFJV获得的结果 由于喷气式飞机的设计和操作范围广泛，因此很难进行比较 不同临床组别所使用的参数。对所有这些都至关重要 问题是缺乏对物理机制的清楚了解 新生儿HFJV的手术治疗为了得到一些这样的东西 理解，建议进行研究以调查喷气式飞机的假设 喷嘴的设计和位置对整体性能有很大影响 高频气体交换效率与气管壁剪切率 新生儿喷射呼吸机(HFJV)。我们建议通过以下方式来检验这一假设 利用液体微珠流动可视化实验技术 新生儿支气管树的物理模型。流动可视化 将通过拍摄传统的和高速的电影来实现 在模型中运行的射流所产生的振荡液体流。 物理模型中的液珠流动与气体流动相似。 应用流体机械在新生儿肺内发生HFJV 动力学和几何相似原理。电影画框 拍摄的流量将被开发和分析使用图像分析仪。 通过这一分析，我们将确定实际注入的潮气量 射流；射流对气管壁施加的剪切力；以及 对流风道气体交换过程的总体效率 给出了一套射流的设计、运行和定位参数。压力 在充满液体的模型内的不同位置也将进行测量 同时，并用于预测相应的气体压力在 新生儿呼吸道。主要调查人员已经开发了这项技术 在支气管气道模型中的液体-微珠流动可视化的研究 将其成功地应用于正常呼吸和 高频活塞式振动通风。