RESPIRATORY PUMP FAILURE--APPLIED PHYSIOLOGY

呼吸泵故障——应用生理学

• 批准号: 3470909
• 负责人: Rolf D Hubmayr
• 金额: $ 9.69万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-09-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3470909
• 关键词: biomechanics; diaphragm; dogs; electrostimulus; fatigue; human subject; muscle contraction; neuromuscular transmission; phrenic nerve; pulmonary respiration; respirators; respiratory airway pressure; respiratory airway volume; respiratory imaging /visualization; respiratory insufficiency /failure; respiratory muscles

The ultimate goal of this proposal is to test the following hypotheses: a) hypercarbic respiratory failure during weaning from mechanical ventilation usually results from diaphragm fatigue, and b) diaphragm fatigue results from an imbalance between the mechanical load on the respiratory muscles and their endurance. Three studies are presented. The aim of Protocol 1 is to verify the importance of diaphragm fatigue in the pathophysiology of hypercarbic respirtory failure in patients. The response of the diaphragm to bilateral phrenic stimulations will be evaluated in ventilator-dependent patients before and after failed weaning attempts. Diaphragm fatigue will be defined as a fall in the transdiaphragmatic twitch pressure between pre and postweaning states. The results will determine: a) the incidence of fatigue, and b) whether fatigue is a failure in neuromuscular transmission and/or excitation contraction coupling. This study will also give information concerning: a) the time necessary for recovery from fatigue, and b) the predictive value of less invasive measurements such as inspiratory work, inspiratory muscle strength, airway occlusion pressure, transdiaphragmatic pressure (PDI), breathing pattern, thoracoabdominal motion, the power spectral analysis of the diaphragm EMG, and gas exchange variables. The aim of Protocol 2 is to validate PDI generated by bilateral phrenic stimulation as an index of diaphragm contractility in normal man. In normal volunteers, PDI produced by bilateral phrenic nerve stimulation will be evaluated as a function of lung volume during relaxation and while thoracoabdominal shape is being systematically altered by a pneumatic device which displaces the thorax and abdomen along an isovolume line. It will thus be determined whether abdominal volume at a constant lung volume has a significant independent effect on diaphragm function. The specific aim of Protocol 3 is to determine the relationship between PDI generated by bilateral phrenic stimulation and regional diaphragm mechanics in the dog. To assess the limitations of PDI as an index of global diaphragm function, regional diaphragm function and its relationship to PDI will be evaluated in the dog. By adapting the videoroentgenographic marker technique for studying regional lung function to the diaphragm, the regional contractility will be evaluated in vivo under conditions of defined initial lengths and loads.

该提案的最终目标是测试以下内容 假设：a) 断奶期间出现高碳酸性呼吸衰竭 机械通气通常由膈肌引起 疲劳，以及 b) 膈肌疲劳是由不平衡引起的 呼吸肌的机械负荷与其呼吸肌的机械负荷之间的关系 耐力。 提出了三项研究。 协议1的目的是验证隔膜的重要性 疲劳在高碳酸血症性呼吸衰竭的病理生理学中的作用 患者。 膈肌对双侧膈肌的反应 将在依赖呼吸机的患者中评估刺激 尝试断奶失败之前和之后。 隔膜疲劳会 被定义为跨膈抽搐压力的下降 断奶前和断奶后状态之间。 结果将决定： a) 疲劳的发生率，以及 b) 疲劳是否是一种失败 神经肌肉传递和/或兴奋收缩 耦合。 这项研究还将提供有关以下方面的信息：a) 从疲劳中恢复所需的时间，以及 b) 预测 吸气功等侵入性较小的测量的价值， 吸气肌力量、气道闭塞压、 跨膈压 (PDI)、呼吸模式、 胸腹部运动的功率谱分析 隔膜肌电图和气体交换变量。 协议 2 的目的是验证双边数据生成的 PDI 膈刺激作为膈肌收缩力的指标 正常人。 在正常志愿者中，双侧神经产生的 PDI 膈神经刺激将作为肺功能进行评估 放松时的体积以及胸腹形状 通过气动装置系统地改变 沿着等体积线移动胸部和腹部。 它将 从而确定腹腔体积是否在恒定的肺 体积对膈肌有显着的独立影响 功能。 协议 3 的具体目标是确定关系 双侧膈刺激产生的 PDI 和 狗的局部膈肌力学。 评估 PDI 作为整体膈肌功能指标的局限性， 局部膈肌功能及其与 PDI 的关系为 在狗身上进行评估。 通过适应视频X线摄影 研究区域肺功能的标记技术 隔膜，将在体内评估区域收缩力 在规定的初始长度和载荷的条件下。