ON-LINE STUDIES OF PULSATILE PULMONARY HEMODYNAMICS

我提出了实验与理论相结合的方法来研究(1) 多种生理状态下的搏动性肺血流动力学在线 和病理条件以及(2)改善和关联现有的 血流动力学的研究方法。这样做的长期目标是 该项目有两个方面：(1)科学地理解人的行为 脉动流条件下的肺血管系统和限制身体 已经通过稳定流动获得的信息的结果来自 脉动流实验；(2)在实践中，建立明显的 在不同条件下的阻抗谱模式以及使用这样的 信息作为在线评估肺功能状态的手段 血流动力学。 实验将在狗身上进行，包括两个基本准备：(1) 右心完好，左肺插管，开胸或闭合 胸部；(2)离体左下叶，原位或体外灌流 通过脉动泵。在第一种制备中，瞬时压力-流量 关系将被准确记录和肺血管输入 阻抗将在线计算。在第二种准备中，动脉 和静脉闭塞(AVO)将以精确和输入的方式应用 还将进行阻抗测量。这些数据将被分析为 在线和离线。 由于AVO技术引起血管的脉冲反应 系统在时间域和输入阻抗中表征血管 系统在频域中，将尝试将 从这两种方法得到的结果。 在完整的右心实验中，压力-流量关系 在肺血管床排出的短暂时间内 被动型将被特别考察。左心房对心脏功能的影响 整个肺血管床的搏动性也将是 调查过了。 本项目将研究的病理生理条件包括 肺膨胀、低氧、对5-羟色胺、异丙肾上腺素和 去甲肾上腺素输注、血液稀释、肺栓塞、急性肺 损伤合并通透性水肿、静水性水肿、内毒素休克、 失血性休克以及IPPB通气和呼气末正压的影响。

I propose a combined experimental-theoretical approach to (1) study pulsatile pulmonary hemodynamics on-line under a variety of physiological and pathological conditions and (2) to improve and correlate two existing methods of investigation in hemodynamics. The long-term objective of this project is two-fold: (1) scientifically, to understand the behavior of the pulmonary vasculature under pulsatile flow conditions and to limit the body of information which has been obtained with steady flow to the results from the pulsatile flow experiments; (2) practically, to establish distinct patterns of the impedance spectra under different conditions and use such information as a means of online evaluation of the state of pulmonary hemodynamics. Experiments will be performed in dogs with two basic preparations: (1) intact right heart and cannulated left lung, either open chest or closed chest; (2) isolated left lower lobe, either in situ or in vitro, perfused by a pulsatile pump. In the first preparation instantaneous pressure-flow relationships will be recorded accurately and pulmonary vascular input impedance will be computed on-line. In the second preparation, arterial and venous occlusion (AVO) will be applied with precision and input impedance measurements will also be made. These data will be analyzed both on-line and off-line. Since the AVO technique elicits the impulse responses of the vascular system in the time-domain and input impedance characterizes the vascular system in the frequency-domain, an attempt will be made to correlate the results obtained from these two methods. In the intact right heart experiments, the pressure-flow relationship during the brief period when the pulmonary vascular bed discharges passively will be examined in particular. The effect of the left atrium on the pulsatility in the entire pulmonary vascular bed will also be investigated. The pathophysiological conditions to be studied in this project include lung inflation, hypoxia, effects on serotonin, isoproterenol and norepinephrine infusion, hemodilution, pulmonary embolism, acute lung injury with permeability edema, hydrostatic edema, endotoxic shock, hemorrhagic shock, and effects of IPPB ventilation and PEEP.