Firstly, when it comes to atomiser types, there are three main categories of common atomisers:

• Ultrasonic nebulizer, this nebuliser produces a relatively large amount of nebulisation, but due to the production of liquid particles are not fine enough, sensitive patients are prone to hypoxia inhalation, and the ultrasonic nebuliser will make the liquid knotted into beads of water hanging on the wall of the inner cavity, the effect on the lower respiratory tract diseases is worse, and therefore suitable for upper respiratory tract treatment;
• Mesh nebulizer, this nebuliser produces finer atomised particles, generally within 3μm, for better deposition in the lower respiratory tract, terminal bronchioles and alveoli, whereas infants and young children have narrower respiratory tracts, and in order to deliver the medication into the bronchioles, the use of micro-mesh nebulisers is recommended;
• Compression nebulizer, this is the most common one, its principle is through the high-speed movement of the compressed gas to impinge on the cracking drug into tiny air-soluble particles, its nebulisation output is large and fast, while the output of the drug particles fine, and the use of the liquid residue after the use of a lower amount.

Secondly, in terms of the size of nebulised particles, different sizes of nebulised particles are suitable for different types of diseases and act on different airways, which are usually divided into 4 zones:

• 10-15μm: The vast majority of drug particles will remain in the oropharynx and eventually enter the body through swallowing;
• 5-10μm: mainly acts on the upper airway, suitable for pharyngeal diseases.
• 1-5μm: It can reach below the middle airway and bronchial tubes, and is better for asthma, cough-related respiratory diseases, and nebulised absorption treatment of pneumonia diseases.
• ＜5μm: Although drug particles reach the lower respiratory tract, 90 per cent of them are eliminated from the body with the respiratory tract;

The finer the nebulised particles the higher the rate of deposition of the drug in the lungs and the more effective the treatment will be, but as far as possible not less than 0.5 microns, otherwise it may be eliminated without absorption.

Again, in the atomisation rate, can only indicate the speed of the drug being atomised, but does not represent the size of the atomised particles and the absorption of the human body, so it is necessary to combine with other parameters for selection.

In general, a nebulisation rate of 0.2-0.4 ml/min is appropriate;

Too low a rate of nebulisation can lead to prolonged treatment time and the drug is not easily deposited in lower respiratory tract disease;

Too fast a rate of nebulisation can lead to choking and wastage of the drug;

Finally, in terms of power, duration of continuous operation, and noise level are also factors in choosing an atomiser.