Development of an Active Mechanical Lung for Simulating Human Pulmonary Ventilation / 中国医疗器械杂志

At present, the passive simulated lung including the splint lung is an important device for hospitals and manufacturers in testing the functions of a respirator. However, the human respiration simulated by this passive simulated lung is quite different from the actual respiration. And it is not able to simulate the spontaneous breathing. Therefore, including" the device simulating respiratory muscle work "," the simulated thorax" and" the simulated airway", an active mechanical lung to simulate human pulmonary ventilation was designed:3D printed human respiratory tract was developed and connected the left and right air bags at the end of the respiratory tract to simulate the left and right lungs of the human body. By controlling a motor running to drive the crank and rod to move a piston back and forth, and to deliver an alternating pressure in the simulated pleural, and so as to generate an active respiratory airflow in airway. The experimental respiratory airflow and pressure from the active mechanical lung developed in this study are consistent with the target airflow and pressure which collected from the normal adult. The developed active mechanical lung function will be conducive to improve the quality of the respirator.

Modeling the noninvasive bi-level positive airway pressure ventilation therapy system and simulated application / 生物医学工程学杂志

Without artificial airway though oral, nasal or airway incision, the bi-level positive airway pressure (Bi-PAP) has been widely employed for respiratory patients. In an effort to investigate the therapeutic effects and measures for the respiratory patients under the noninvasive Bi-PAP ventilation, a therapy system model was designed for virtual ventilation experiments. In this system model, it includes a sub-model of noninvasive Bi-PAP respirator, a sub-model of respiratory patient, and a sub-model of the breath circuit and mask. And based on the Matlab Simulink, a simulation platform for the noninvasive Bi-PAP therapy system was developed to conduct the virtual experiments in simulated respiratory patient with no spontaneous breathing (NSB), chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). The simulated outputs such as the respiratory flows, pressures, volumes, etc, were collected and compared to the outputs which were obtained in the physical experiments with the active servo lung. By statistically analyzed with SPSS, the results demonstrated that there was no significant difference ( P > 0.1) and was in high similarity ( R > 0.7) between the data collected in simulations and physical experiments. The therapy system model of noninvasive Bi-PAP is probably applied for simulating the practical clinical experiment, and maybe conveniently applied to study the technology of noninvasive Bi-PAP for clinicians.

Experimental Study on Respiratory Mechanical Parameters of the Patient with Aute Respiratory Distress Syndrome under High Flow Nasal Cannula / 医用生物力学

Objective T o analyze the influence of high flow nasal cannula (HFNC) on trespiratory mechanical parameters of the patient with acute respiratory distress syndrome (ARDS) based on ventilation experiment, and investigate the therapeutic and side effects of the HFNC. Methods The HFNC ventilation system model based on MATLAB and the physical experiment platform based on active simulated lung ASL5000 were developed to simulate the respiratory movement of ARDS patients with different lung compliance, and a series of the HFNC ventilation experiments were carried out. Both experimental results in MATLAB and physical platform were compared and analyzed. Results The results from the Matlab model-based simulation experiment and physical platform based-physical experiment uniformly showed that increasing the output flow of HFNC would decrease the relevant respiratory mechanical parameters of respiratory flow and tidal volume, but increase the intrapulmonary pressure and the functional residual capacity (FRC). Under the condition of small flow, the output flow from HFNC might be smaller than the inspiratory flow required by the patient, and an inspiratory compensation flow was necessary to make up for the inspiratory flow. Conclusions The necessary reliable compensation flow in inspiration will promote the security of HFNC. Understanding the changes in respiratory mechanical parameters of ARDS patient will be beneficial to pre-evaluate the HFNC, improve the ventilation effect and reduce the ventilation risks.

Matlab-Based Study on Online Monitoring of Respiratory Resistance and Compliance under Noninvasive Positive Airway Pressure Ventilation / 医用生物力学

Objective Under noninvasive positive pressure ventilation, in view of inconvenient operations in human airway, and avoiding the interference of spontaneous breathing and the necessary leakage flow, the method for dynamic online monitoring of the respiratory resistance (R) and compliance (C) was studied.Methods At the end of expiration, when the exhaled flow was 0, relative to the expiration positive airway pressure (EPAP), a step-dropped pressure was produced with the amplitude Δp and hold time Δt. Under this dropped pressure, a short-time discharged flow was generated from the lung, and the discharged flow was applied to calculate the R and C. In addition, a respiratory model was developed in MATLAB to simulate the breaths of normal adult, acute respiratory distress syndrome (ARDS) patient and chronic obstructive pulmonary disease (COPD) patient. A serial of simulation experiments were carried out for obtaining data and verification.Results The calculated R and C from simulation for normal adult, ARDS patient, COPD patient, deviated from the actual value by 1.60% and -1.60%, 1.21% and -1.19%, -12.53% and 14.32%, respectively.Conclusions The proposed algorithm is practicable and feasible for calculating the R and C. The simulation results are beneficial for studying and realizing the intelligent ventilation and proportional assist ventilation in respirator.

Circuit Designed for Driving Blower in Non-invasive Positive Airway Pressure Respirator / 中国医疗器械杂志

One of critical technologies in a non-invasive positive airway pressure respirator is to output the airflow for meeting the requirement of respiratory patient in breath. In order to develop a safe and reliable blower driving system, a circuit based on the special chips MC33035 and MC33039 was designed. The linear relationship between the input control voltage and the output air flow was achieved. This designed circuit will be embedded in the non-invasive ventilator system as a module. And based on this circuit, the secure and controllable ventilation flow can be performed.

Prospects and developments in the technologies of high frequency oscillatory ventilation / 生物医学工程学杂志

The high frequency oscillatory ventilation (HFOV) is characterized with low tidal volume and low mean airway pressure, and can well support the breathing of the patients with respiratory diseases. Since the HFOV was proposed, it has been widely concerned by medical and scientific researchers. About the HFOV, this paper discussed its current research status and prospected its future development in technologies. The research status of ventilation model, mechanisms and ventilation mode were introduced in detail. In the next years, the technologies in developing HFOV will be focused on: to develop the branched high-order nonlinear or volume-depended resistance-inertance-compliance (RIC) ventilation model, to fully understand the mechanisms of HFOV and to achieve the noninvasive HFOV. The development in technologies of HFOV will be beneficial to the patients with respiratory diseases who failed with conventional mechanical ventilation as one of considerable ventilation methods.

Investigating the mechanism of the high frequency ventilation for the oscillation airflow between left and right lungs / 生物医学工程学杂志

Traditionally, adequate tidal volume is considered to be a necessary condition to support respiratory patient breathing. But the high frequency ventilation (HFV) with a small tidal volume can still support the respiratory patient breathing well. In order to further explore the mechanisms of HFV, the pendelluft ventilation between left and right lungs was proposed in this paper. And a test platform by using two fresh sheep lungs was developed for investigating the pendelluft ventilation between the left and right lungs. Furthermore, considering the viscous resistance ( ), inertance ( ) and lung compliance ( ) in the lung, a second-order lung ventilation model was designed to inspect and evaluate the pendelluft ventilation between left lung and right lungs. On referring to both results of experiments in practice and simulation in MATLAB Simulink, between the left and right lungs, the phase difference in their airflow happens during HFV at some frequencies. And the pendelluft ventilation between the left and right lungs is resulted by the phase difference, even if the total airflow entering a whole lung is 0. Under HFV, the pendelluft ventilation between left and right lungs will benefit the lungs being more adequately ventilated, and will be improve the utilization rate of oxygen in the lungs.