Development And Application Of Ventilator

- May 21, 2020-

1. The degree of computerization of the ventilator

The degree of computerization of the ventilator determines the grade of the ventilator, which is expressed in:

(1) There is a self-checking function after starting up.

(2) There is a screen prompt when a fault occurs to facilitate maintenance.

(3) Perfect alarm functions, such as oxygen supply, gas supply, minute ventilation, upper pressure limit, lower pressure limit, respiratory rate, tidal volume, suffocation ventilation, background ventilation setting, machine disconnection, air leakage and air leakage volume, flow rate Sensors, working conditions, oxygen flow and many other links ensure the safety of the mechanical ventilation process. Clinicians can adjust the alarm range set by the parameters according to the state of the patient.

(4) Other special functions, including sputum suction function, atomization function, breath holding function (including inhalation and exhalation breath holding, to meet the needs of chest radiographs), lock function (to prevent the ventilation parameters from being changed arbitrarily)

2. The monitoring function of the ventilator

The monitoring function of the ventilator is one of the key links that determine the grade of the ventilator. The perfect ventilator monitoring function is an important prerequisite for the ventilator to adapt to the pathological and physiological changes of the lungs of patients. k, P, Pn one, VA, V Leak, I: E and can further display:

(1) Pressure-time, volume-time, flow-rate-time curves can be displayed on a single screen or simultaneously.

(2) spo2, ETCO2 and calculate VD / VTe, co2 output.

(3) Monitor the traces of Paw-V, V-Flow, Flow-Paw, V-co2, Ptrach-V, Flow-Ptrach and other curve loops.

(4) Trend review (24-48 hours).

(5) The logbook is the review of the settings of ventilator application events.

(6) Calibration function, including the calibration of co2, Flow, o2.

(7) Ventilation and setting of various functions: the size of the volume, different combinations of screen displays, any choice of ventilation mode (more than 10 commonly used methods), multiple voice settings, etc.

(8) The ventilator allows the user to trace the P-V curve [1,2,3 J with a low flow rate method to further understand the patient's lung static compliance (c), resistance (R), and endogenous PEEP (PEEPi). Furthermore, it provides a basis for better adjustment of ventilation parameters. Through curve tracing, the upper and lower inflection points can be calculated, and the re-tensor volume can be printed online with the computer.

(9) The integration of other devices in the ventilator (“bi-core” of the respiratory mechanics monitor) enhances the resolution of problems that cannot be understood by using breathing parameters alone during ventilation, such as respiratory mechanics monitoring, placement of esophageal pressure, and intragastric pressure monitoring to understand Transpulmonary pressure, transdiaphragm pressure and dynamic auto-PEEP can further clarify the respiratory mechanics and provide scientific research space for clinical professionals.

(10) After years of clinical practice, foreign ventilator manufacturers promptly integrated some useful parameters such as RVR, MIP, Po. 1. PlP and au P are put into the monitoring system to _4J to provide a basis for the adjustment and offline setting of clinicians. The offline mode of automation has risen quietly in recent years_5. 5. The ventilator integrates the patient's important parameters, weight, ideal ventilation parameters, and BGA, which improves the level of mechanical ventilation and shortens the time of taking the machine. In short, the computerization and networking of the ventilator provide a scientific research platform for mechanical ventilation and promote the development of the application level of mechanical ventilation_6J.

3. The development of the ventilator mode is an important manifestation of the level of the ventilator. Whether the ventilator is volume control or pressure control, it leads to ventilator-related lung injury (Ventilator-induced Lung Inj ~ y VILI) E3] In the past, foreign countries have done a lot of basic and clinical research in this area, and made major reforms on the basis of the original IPPV, IMV, SIMV, PSV, etc. Many studies have shown that the autonomous model of stress can achieve a non-protection strategy and maximize To reduce the occurrence of VILI and further expand the role of ventilator as a clinical treatment. (1) Today's ventilator applications range from newborn to adult, and only need to replace the humidifier and pipeline; mechanical ventilation from non-invasive to invasive, non-invasive ventilation has strong leakage compensation.

(2) Increasing Autoflow or flow-by in volume-controlled ventilation mode increases patient autonomy, reduces airway pressure, increases patient comfort, and overcomes the shortcomings of volume ventilation mode.

(3) Response time (30-40ms) for ventilator breathing, waveform of breathing (square wave-constant flow, deceleration wave), trigger sensitivity is adjustable for flow rate trigger, pressure trigger for abandonment, expiration sensitivity for PSV mode (Es. end) adjustable. Under the monitoring of the ventilator, clinicians can easily adjust the patient's Esem, thus solving the human-computer interaction method can minimize the interference of cardiopulmonary function and the occurrence of VILI.

(4) International clinical practice further confirms that pressure ventilation is superior to volume control in maintaining positive airway pressure, reducing cardiopulmonary interference, improving oxygenation, and minimizing the occurrence of VILI. On the basis of PCV, BiPAP / PS and APRV have been launched in recent years. In particular, BiPAP ventilation mode is used by many ventilator manufacturers because of its pressure control, good coordination between human and machine, and the universal ventilation mode is named: Bilevel, duoPAP and other different names.

(5) Autonomous ventilation and closed-loop ventilation modes: Experimental and clinical applications show that the time for controlling ventilation is minimized to minimize the occurrence of VILI, and the time to take the machine is shortened. Many studies have shown that spontaneous breathing has many advantages, which is conducive to the recovery of patients' physiological changes. For spontaneous breathing, it is no longer the simple Spon mode in the past, but a servo mode (servo) and closed-loop ventilation mode. The biggest advantage lies in the system. The internal output information can be accurately controlled. It can quickly reach a steady state under the premise of zero error, and can eliminate all kinds of external interference. The mechanical ventilation technology using the closed-loop control principle can be made quite simple or complex. The simplest closed-loop control is to control an output variable, such as PSV, based on inputting a piece of information. Relatively complex closed-loop control can continuously regulate multiple output variables based on multiple input information. Dual control is to control the output pressure and volume synchronously in one ventilation or every ventilation. Ventilation technology that uses the principle of dual control within one ventilation has capacity to guarantee pressure support ventilation (Ⅵ) and pressure amplification (PA). The goal of ventilation is to reduce the patient's inspiratory work on the premise of ensuring the minimum inhaled tidal volume and minute ventilation. Others include: PRVC, autoflow, VTPC (volume calibration pressure control), and its technical principle is that the ventilator follows the patient's respiratory mechanics Characteristic changes automatically adjust the inspiratory pressure and inspiratory flow rate to ensure that vT tends to be constant during each ventilation. The ventilator performs negative feedback control for each ventilation. According to the principle of closed-loop ventilation control, closed-loop ventilation is divided into: positive feedback ventilation (PAV), negative feedback ventilation (APV, ASV, PRvC), inter-respiratory closed-loop ventilation (MMV, APV, ASV) and intra-respiratory closed-loop ventilation (nw).

In the past 20 years, PSVE7,8,9J have been welcomed by clinicians, and the success rate of ventilator-dependent patients has improved offline. Given that PSV is a constant pressure inspiratory support, at low levels of Ps, its VT must be over-supported. , Support is equivalent, support is less than three stages, there are inhalation delay and exhalation delay in this mode, when this mode is applied, it is prone to human-machine synchronization. In recent years, many manufacturers have increased the exhalation sensitivity adjustment (Esens) to the exhalation phase, which greatly reduces the occurrence of man-machine synchronization and improves the clinical application effect. However, clinicians still have many difficulties in identifying and adjusting, and cannot observe the waveform. Very easy to identify. In the past 10 years, PAV or PPS mode ventilation has become the focus of contemporary critical illness research [10,11,12]. This mode provides pressure support in proportion to the patient ’s respiratory effort to solve the human-machine coordination in PSV ventilation. By understanding the patient ’s resistance 3. Changes in compliance, or use target adjustment methods to adjust the settings of the ventilator (VA and FA), the ventilator set pressure is too high, the volume is too high, and the suffocation ventilation alarm ensures the safety of the mode and reduces the ventilator dependence Significantly shorten the process of taking the machine. There are currently DIs internationally. ea company, PB company, Wellcome company has this mode, PB840 has also adopted the automatic setting method is more convenient to use this mode. This closed-loop model is being recognized by clinicians. (6) Automatic Catheter Compensation (AT ℃) Automatic Catheter Compensation is an instantaneous compensation for the resistance pressure generated by different caliber flow rates of artificial airway catheters. Different calibers and different flow rates have different compensation resistance pressures, and the compensation range is from 0-100% different. The ventilator can be reflected on the curve and waveform. The setting of ATC is convenient for clinicians to observe and evaluate spontaneous breathing ability, and it is easy to achieve offline when implementing low-assisted ventilation.

4. Adjustment of ventilator

Modern ventilators have changed the single function of multiple knobs in the past, using a single knob adjustment method, which is convenient for clinical use. Using digital adjustment increases the accuracy of parameter setting. At the same time, the clinician must have rich theoretical and practical experience to make the parameter setting more in line with the patient's condition. The ventilator also stipulates the safe range of conventional parameters. If it exceeds the range, it needs to be confirmed, which increases the safety of mechanical ventilation. Due to the enhanced monitoring and display function of the ventilator, the set parameters are clearly displayed, which is beneficial to the clinician to evaluate the patient's condition, and can be transmitted through the network and is also convenient for the management and guidance of mechanical ventilation.

5. Principles for purchasing ventilator

Ventilator is a useful tool for respiratory support, and is a commonly used treatment method for critically ill patients today. Respiratory support is directly related to the rescue level of critical patients. The following principles should be followed when purchasing a ventilator:

(1) Understand the development and application status of ventilator, monitoring and ventilation mode determine the level of ventilator.

(2) According to the scale of the hospital, whether it is a comprehensive ICU or a specialist ICU, it is estimated that the type of disease to be treated is an application-oriented unit or a large hospital for medical, teaching and research.

(3) According to the experience of using ventilator, ICU doctor level, do not buy high-end machines one-sidedly. The development of ventilator is the same as that of other medical devices. It is updated quickly, which not only solves clinical problems but also avoids waste of resources. In summary, the treatment of intubated patients with ventilator is a complicated system engineering, that is, the grade of the ventilator is related to the level of the doctor who uses the ventilator, the respiratory management of the nurse, and the overall strength of the hospital (each auxiliary department). One-sided pursuit of high-end machines may not necessarily improve the success rate of respiratory failure rescue.

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