1, small volume atomizer (SVN) is also called jet atomizer, manual atomizer, medical atomizer or wet atomizer. At present, it is the most commonly used aerosol generator in clinic. Working principle: compressed air (gas compressed air compressed atomizer) or oxygen (driving force) passes through a narrow nozzle at high speed. According to the Venturi effect, negative pressure is generated around the nozzle, and the liquid medicine in the storage tank is brought into the high-speed airflow and crushed into droplets with different sizes, of which more than 99% are composed of large particles. The remaining fine particles fall back to the storage tank through the interception and collision of the nozzle and are ejected at a certain speed, and the crashed particles are re-atomized. Clinical application of jet atomizer can treat bronchodilators, hormones, antiallergic drugs and antibiotics by atomizing inhalation. Generally, the driving gas flow rate of the spray atomizer is 6L/min-8L/min, and the liquid medicine in the liquid storage tank is 4ml-6ml. For the solution with high atomization viscosity, the driving gas flow rate can be increased, but the maximum gas flow rate does not exceed 12L/min.
How to use:
① Put the medicine to be inhaled into the liquid storage tank;
② Dilute the medicine in the liquid storage tank to 4 ml-6 ml;
③ Adjust the gas flow (generally 8 l/min);
(4) connecting the nozzle and the mask with the patient;
⑤ Patients are required to breathe slowly (normal tidal volume) and take deep breaths at regular intervals until the total lung volume reaches 4 s-10s;
⑥ The continuous atomization time is about 65438±05min；;
⑦ Observe the effect and side effects of patients after atomizing inhalation.
2. The working principle of ultrasonic atomizer is to convert electric energy into high-frequency vibration of ultrasonic thin plate, and high-frequency vibration converts liquid medicine into aerosol particles. The size of fog particles produced by ultrasonic atomizer is inversely proportional to the ultrasonic vibration frequency: the higher the vibration frequency, the smaller the aerosol particles; On the contrary, the intensity of ultrasonic vibration is directly proportional to the number of aerosol particles: that is, the stronger the vibration, the more aerosol particles are produced and the greater the density. The particle size of aerosol produced by ultrasonic atomizer is 3.7um-10.5um. It should be noted that patients with hypoxia or hypoxemia should use it with caution or not for a long time, because the aerosol produced by ultrasonic atomizer has a high density and the oxygen partial pressure in the airway is relatively high after inhalation.
3. The mesh atomizer belongs to a new type atomizer.
(1) metered-dose inhaler
MDIs is the most widely used aerosol generator at present. It has the advantages of quantification, simple operation, portability, convenient use, no need for regular disinfection and no cross infection in hospital, so it is widely welcomed.
1. working principle: the sealed medicine storage tank is filled with medicine and booster (usually freon). The medicine is dissolved or suspended in the liquid booster, and the liquid medicine can be communicated with the quantitative chamber through the quantitative valve and then sprayed out through the nozzle. After encountering atmospheric pressure, the propellant is rapidly ejected due to sudden evaporation, and the liquid medicine is taken out and atomized into aerosol particles. The diameter of aerosol particles produced by MDIs is about 3 μ m-6 μ m.
2. Correct usage: shake the liquid medicine evenly before each use. The patient exhaled deeply to the level of residual gas, opened his mouth, placed the MDIs nozzle 4cm in front of his mouth, and slowly inhaled (0.5L/s) to almost the whole lung volume level. At the beginning of inhalation, press your fingers to spray medicine, hold your breath for 5s- 10s at the end of inhalation, and then exhale slowly to the level of functional residual gas. You can use it again after a rest of about 3 minutes. This method is suitable for all patients who inhale any medicine except infants.
3. The dedicated MDIs MDIs can improve the inhalation effect of aerosol atomization with the help of fog storage device, because the application of fog storage device can reduce the initial velocity of aerosol sprayed by MDIs, increase the distance between MDIs nozzle and oral cavity, and reduce the sedimentation of aerosol particles in oral cavity; The biggest advantage of connecting MDIs with fog storage device is that patients don't need the coordinated action of spraying medicine and inhaling. It can be used for patients who are difficult to master the routine use of MDIs or children and infants who cannot cooperate. But it is bulky and inconvenient to carry.
(2) Dry powder inhaler
1. Single-dose inhalers are usually rotary or rotary inhalers, with a sharp needle on the rotary disk and dry powder inhaled into capsules. When in use, the drug capsule is first put into the adsorber, and then gently rotated to make the turntable and the needle on the turntable smash the capsule; The patient can inhale deeply through the catheter in the mouth, thus driving the spiral blade in the absorber to rotate and stirring the dry powder of medicine to make it into aerosol particles for inhalation. The sedimentation rate of atomized particles in the lungs of single-dose inhalers is about 5%-6%, which is rarely used. It is often used to inhale sodium crotonate dry powder to prevent allergic asthma in children.
2. Multi-dose disc inhalers usually include Dubao and disc inhalers. Inhaled dry powder is packed in capsules. Multiple doses can be filled into the inhaler at one time. When in use, the shell is rotated or the sliding disk is pushed and pulled to transfer one dose at a time, and the patient pulls up the cover shell which is connected with it in a tit-for-tat manner, and pierces the capsule containing the powder, that is, the suction nozzle with the inhaler in its mouth deeply sucks out the powder, inhales for 5s- 10s, and then exhales slowly. The multi-dose inhaler can be reused, and the inhaled aerosol particles are pure powder, which does not contain flux and surfactant. The operation method is simple and easy to carry, so it is welcomed by patients and meets the requirements of environmental protection. The biggest advantage of multi-dose inhaler is that the inhalation of powder is driven by the patient's breathing, and there is no need for coordinated action of deliberate breathing and hand pressure. The disadvantage is that it may be restricted for patients with chronic obstructive pulmonary disease with decreased respiratory muscle strength, patients with severe asthma attack, infants with weak respiratory muscle strength and younger children.