The application of flow sensors in ventilator has its own advantages and disadvantages, and various manufacturers are constantly improving. How to solve the shortcomings of various types of sensors in terms of durability, accuracy, cost, and easy cleaning and disinfection, adapting to various disinfection methods for patients with infectious diseases after use .
In the medical industry, ventilator applications are very common.
The basic composition of the ventilator
The common ventilator is mainly composed of two parts: â‘ air circuit unit: inhalation valve (including oxygen valve and air valve), oxygen concentration sensor, safety release valve, pressure sensor, humidification and heating device, breathing circuit, exhalation Valve and PEEP valve, exhalation flow sensor; â‘¡ Host: control main board (the control core of the work of each component), display screen (setting ventilation parameters and monitoring respiratory mechanics parameters);
Daily maintenance of flow sensor on ventilator
At present, the main types of flow sensors are: differential pressure type (Hamilton, BEAR series, etc.), pressure induction type, hot wire type, crystal hot film type (PB840), ultrasonic flow sensor.
1 The use of a differential pressure flow sensor requires that the pressure measurement hole be at the top to prevent condensate from the breathing tube from entering the sensor and affecting the monitoring of the sensor. The temperature set by the humidifier should be appropriate. Excessive humidification of the condensate on the restrictor will affect the measurement accuracy, especially the near-end differential pressure flow sensor. Durable sensors can be cleaned and disinfected in many ways, such as immersion, gas or high temperature. Note that when the liquid is cleaned, do not rinse the inside with too much water to avoid deformation of the restrictor. When using it, pay attention to the patient's secretions and water blocking the sampling tube to avoid seriously affecting the monitoring accuracy. If it is found that the sampling tube is blocked, inhale oxygen at low pressure to flush out. If the use time is long, the current limiter will gradually age and affect the accuracy, so it should be replaced in time.
2 The pressure-sensing flow sensor is easy to be affected by respiratory secretion or impurities due to the small measurement channel. Use a filter as much as possible, and periodically soak with alcohol for cleaning and disinfection, and use it naturally after drying.
3 When the hot wire flow sensor is used, it is best to use a bacterial filter installed at the far end, which can ensure the detection accuracy and extend the service life of the hot wire. However, if the bacterial filter is used for a long time, the airway exhalation resistance will increase, and it needs to be replaced. Durable design can be disinfected with alcohol. Disinfection precautions: 1: Can't be disinfected in alcohol immediately after use, at least let it cool down for at least 30 minutes, otherwise the hot wire (up to 400 ° C) will burn out immediately . 2: Cleaning and disinfection should be soaked gently, do not shake vigorously in the liquid, so as not to break the hot wire. 3: The sensor is immersed in 70% alcohol for 1 hour. After taking it out, it is allowed to dry naturally.
4 The crystal hot film type flow sensor is installed inside the machine, which is not convenient for disassembly and disinfection. Therefore, a bacterial filter must be used to ensure the detection accuracy and extend the life of the hot film. After the infectious patient has ventilated, the bacterial filter must be replaced or disinfected.
5 Ultrasonic flow sensor cleaning is relatively simple, can be sterilized with gas or liquid, and individual can be sterilized at high temperature. When cleaning, be careful not to hit hard, so as not to affect the crystal. After disinfection, pay attention to the need to dry the electrical signal interface, and there must be no water to avoid short circuit. Ultrasonic membranes will age with time and accuracy will be affected.
The application of flow sensors in ventilator has its own advantages and disadvantages, and various manufacturers are constantly improving. How to solve the shortcomings of various types of sensors in terms of durability, accuracy, cost, and easy cleaning and disinfection, adapting to various disinfection methods after infectious disease .
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