【作者】 易韦韦；

【导师】 王跃科；

【作者基本信息】 国防科学技术大学 ， 仪器科学与技术， 2009， 博士

【摘要】 呼吸机是抢救和治疗各种急慢性呼吸衰减或呼吸功能不全病人的重要工具。通气模式是指导呼吸机通气的规则,直接决定了呼吸机对病人的治疗效果,因此具有重要的研究价值。为提高各通气模式工作的人机协调性以及避免真人试验的危险,论文基于主动模拟肺对通气模式进行了研究,涉及到的关键技术有:通气系统建模、试验平台的建立、系统模型参数的在线估计方法和基于人机协调的通气控制技术等。主要研究内容和结论包括:(1)建立了由顺应性、气阻和呼吸肌产生压力三元素组成的非线性时变呼吸系统模型,并通过对不同病人的临床通气数据分析和与现有各种模型的比较验证了模型的适用性;建立了呼吸机气路各组成部分的气体力学模型。利用上述模型组建了呼吸机/呼吸系统集总参数模型,为通气模式研究提供了理论基础。(2)为避免真人试验的危险,同时针对现有通气模式研究试验平台的呼吸系统模拟能力和在线调试能力差、控制精度低和不能开展辅助通气模式研究等问题,设计了基于主动模拟肺的通气模式研究试验平台。(3)提出了一种管道顺应性的预通气测量方法,为量化分析管道对呼吸机输出气流的分流影响提供了条件;提出了一种基于比例辅助通气的最小二乘生理估计法,理论分析和试验结果表明,该估计法较M.Younes方法而言,将呼吸系统气阻估计的有效率由48.9%提高到了73.7%,消除了单点测量误差,提高了呼吸系统气阻和顺应性的估计精度。(4)为提高通气过程中的人机协调性能,针对保证通气水平、确保通气安全和减少人机不同步这三个问题,提出了相应的改善方法,具体包括:①提出了一种潮气量比例补偿方法和一种有创通气时气道压的补偿方法。理论分析和试验结果表明,潮气量从未补偿前的EC /( EC + E rs )×Vset提高到了设定值Vs et,气道压从未补偿前的Pr ef ?λRT V提高到了设定值Pr ef,确保了病人通气水平。( Er s是呼吸系统弹性系数, EC是呼吸机管道弹性系数, Rr s是呼吸系统气阻, RT是气管插管气阻,λ是自动补偿因子)②实现了PI参数模糊自整定通气控制方法。试验结果表明,方法较传统PI控制方法而言,有效地减小了压力过冲和振荡,减少了两者对病人安全的危害,提高了通气安全。③提出了一阶自适应通气控制方法。理论分析和试验结果表明,方法消除了压力过冲和振荡,实现了压力上升时间的准确可控,还能让呼吸机在保证病人潮气量的前提下采用最小的气道压力进行通气,从而减少高气道压对病人的危害,进一步提高了通气安全。④引入基础流实现了流量和压力双反馈型控制通气。理论分析和仿真结果表明,这种控制方法更能够及时有效地跟踪病人呼吸肌运动,提高了人机同步性能,同时方法有效地降低了呼吸机有效输出阻抗,减少了呼吸机对病人的做功,有利于病人自主呼吸能力的恢复。⑤依据专家经验知识,采用模糊逻辑和推理技术,实现了压力支持水平的在线自动调节。仿真结果与实际调整结果的对比表明,方法实现了指定周期的压力支持水平的最佳选择,确保了生理参数指标处于安全水平,减小了压力支持水平不合适引发的通气安全和人机不同步问题出现的几率。(5)成功地实现了容量控制和压力控制通气模式,并将其应用于麻醉机AS3000上,临床数据表明了它们工作的有效性;在Shangrila590呼吸机上实现了压力支持通气模式。试验表明了模式在压力上升时间的可控性、气道压的稳定性这两个性能上接近甚至优于国外品牌呼吸机上的压力支持模式;首次在国产呼吸机Shangrila590上实现了容量保障压力支持通气、压力调节容量控制通气和适应性支持通气这三种双重控制通气模式。试验结果表明,这三种模式工作输出的流量、气道压和容量曲线完全符合要求,可以进一步开展动物和人体实验;采用PI参数模糊自整定法在呼吸机Shangrila590上实现了比例辅助通气模式,并给出了PI控制的PAV系统稳定条件,为开展比例辅助通气模式研究迈出了探索步伐。上述研究工作对进一步开展通气模式研究、改善呼吸机通气性能和提高产品市场竞争力具有一定的参考价值和现实意义。更多还原

【Abstract】 The ventilator is an important tool in treating patients with acute/chronic respiratory failure or insufficiency. The ventilation modes are the ventilation rlues and determine the efficacy of clinical treatment and therefore possess significant research value. In order to improve the man-machine harmony and avoid the risks that exist in live tests, this paper made a profound research based on an active servo lung. And the key technologies included building the model of the ventilation system, establishing the testing platform, estimation of the model’s parameters and control methods of ventilation based on man-machine harmony. The content and final conclusions are as follows:(1) A non-linear time-varying system model is built with compliance, resistance and pressure produced by the respiratory muscles. Its suitability was verified by analyzing the clinical ventilation data from different patients and comparing it with available typical mechanical modes. And the pneumatics models of the blocks of the ventilator gas way were built. By combining the models mentioned above, the lumped parameter model was built, providing basic theories for ventilation mode research.(2) Based on active servo lung, the testing platform for ventilation mode research is established to avoid risks that exist in live tests. This platform aims at eliminating problems caused by the current platform for its poor simulation and debug capacity, low controlling accuracy and inability to conduct the assist ventilation mode.(3) A pre-ventilation measurement method for the circuit compliance is proposed to analyze of the circuit diffluence quantitatively. A least square physiological method based on the proportional assist ventilation(PAV) is presented to estimate the resistence and the compliance of the respiratory system. Compared with M.Younes’method, this method improves the resistance estimation availability from 48.9% to 73.7% and eliminates the single shot measurement error and improves the estimation accuracy.(4) In order to improve the man-machine harmony during ventilation, and concerning the ventilation level, the ventilation safety and the man-machine synchrony, the corresponding improvement methods are put forward. They are as follows:①A volume proportional compensation method and an pressure compensation method under invasive ventilation are presented to eliminate the impacts caused by the circuit on tidal volume and by the endotracheal tube on the airway pressure, respectively. As proved by the theoretical analysis and the test results, the tidal volume is improved from EC /( EC + Er s )×Vset to the set value Vs et and the airway pressure is improved from Pr ef ?λRT V to the set value Pr ef.( Er s, EC , Rr s, RT andλare the elasticity coefficient of the respiratory system and the circuit, the resistance of the respiratory system and the endotracheal tube, the auto penalty coefficient, respectively.) ②The PI parameter fuzzy self-modified control method has been used. The test results have proved that this method, compared with taditional PI, efficiently reduces pressure overshoot and oscillation, and improves the ventilation safety.③A first order adaptive ventilation control method has been presented. The theoretical analysis and the test results have proved that, by using this method, the pressure overshoot and oscillation are eliminated, that the pressure rise time is accurately controlled, and that under the guarantee for the tidal volume, the smallest airway pressure can be calculated and reduce the hurt of high airway pressure and improve the ventilation safety.④The basis flow has been adopted to gain the flow and pressure double close-up ventilation control method. The theoretical analysis and the simulation results indicate that this method traces the movement of the patient’s respiratory muscles timely and efficiently, improves the man-machine harmony, lowers the effective output resistance of the ventilator, reduces the work that the ventilator does to the patiet and is good for the recovery of the patient’s spontaneous respiration ability.⑤The on-line automatic regulation of the pressure support(PS) level has been realized according to the expertise, the fuzzy logic and reasoning method. Compard the simulation results with actual adjustment results, this method has reached the optimal choice of the PS level, that ensured the safety level of the physiological parameters, and decreased the occurrence probability of the ventilation safety problems and the man-machine asynchrony problems caused by improper PS level.(5) The volume control and pressure control ventilation mode have been successfully realized and applied to the anesthesia machine AS3000, and their validity has been testified by clinical data. The pressure support ventilation mode has been realized on the ventilator Shangrila590, the control ability of the pressure rise time and the stability of the airway pressure is close to or even better than those of the foreign ventilator brands. Three dual control ventilation modes, the volume assured pressure support, the pressure regulted volume control and the adaptive support ventilation mode, have been realized on the Shangrila590, as indicated by the test results, the output flow, the airway pressure and the volume curve of the three modes meet the standard, and we can carry out further animal and human experimentation. By using the PI parameter fuzzy self-modified control method, the PAV mode has been realized on the Shangrila590, and the stability conditions of th PAV system has been obtained, which is a firm step in the quest of the PAV mode research.The above-mentioned investigations have definite referential values and practical meanings for further research on ventilation modes and for improving the ventilator functions and the marketability of the product.更多还原