Nebulizer
Encyclopedia
In medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, a nebulizer (spelled nebuliser in British English
British English
British English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...

) is a device used to administer medication in the form of a mist inhaled into the lungs.
Nebulizers are commonly used for treatment of cystic fibrosis
Cystic fibrosis
Cystic fibrosis is a recessive genetic disease affecting most critically the lungs, and also the pancreas, liver, and intestine...

, asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

, COPD and other respiratory disease
Respiratory disease
Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange possible in higher organisms, and includes conditions of the upper respiratory tract, trachea, bronchi, bronchioles, alveoli, pleura and pleural cavity, and the...

s.

Nebulizers use oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

, compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....

 or ultrasonic
Ultrasonics
Ultrasonics is a term meaning the application of ultrasound. It is often used in industry as a shorthand term for any equipment employing ultrasonic principles....

 power to break up medical solutions/suspensions into small aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

 droplets that can be direclty inhaled from the mouthpiece of the device. The definition of an aerosol is a "mixture of gas and liquid particles," and the best example of a natural occurring aerosol is "mist" (being formed when small vaporized water particles mixed with hot ambient air are cooled down and condense into a fine cloud of visible airborne water droplets). When using a nebulizer for inhalation therapy with medicine to be administered directly to the lungs, it is important to note that inhaled aerosol droplets can only penetrate into the narrow branches of the lower airways if they have a small diameter of 1–5 micrometers. Otherwise they are only absorbed by the mouth cavity, where the effect is low.

History

The first "powered" or pressurized inhaler was invented in France by Sales-Girons in 1858. This device used pressure to atomize the liquid medication. The pump handle is operated like a bicycle pump. When the pump is pulled up it draws liquid from the reservoir, and upon the force of the users hand the liquid is pressured through an atomizer, to be sprayed out for inhalation near the users mouth.

In 1864 the first steam driven nebulizer was invented in Germany. This inhaler, known as: “Siegle’s steam spray inhaler”, used the Venturi principle to atomize liquid medication, and this was the very beginning of nebulizer therapy. The importance of droplet size was not yet understood, so the efficacy of this first device was unfortunately mediocre for many of the medical compounds. The Siegle steam spray inhaler consisted of a spirit burner, which boils water in the reservoir into steam, that flow across the top and into a tube suspended in the pharmaceutical solution. The passage of steam draws the medicine into the vapor, and the patient inhales this out-sprayed vapor through a mouthpiece made of glass.

The first electrical nebulizer was invented in the 1930s and called a Pneumostat. With this device a medical liquid (typically being Adrenalin Chloride, used as a bronchial muscle relaxant to reverse restriction) was made aerosol by the power from an electrical compressor. As an alternative to the expensive electrical nebulizer, many people in the 1930s however continued to use the much more simple and cheap hand driven nebulizer, known as the Park-Davis Glaseptic.

In 1956 a competing technology against the nebulizers was launched by Riker Laboratories (3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....

), in the form of pressurized metered-dose inhaler, with Medihaler-iso (isoprenaline) and Medihaler-epi (adrenaline
Epinephrine
Epinephrine is a hormone and a neurotransmitter. It increases heart rate, constricts blood vessels, dilates air passages and participates in the fight-or-flight response of the sympathetic nervous system. In chemical terms, adrenaline is one of a group of monoamines called the catecholamines...

) as the two first products. In these devices the drug is cold-fill and delivered in exact doses through some special metering valves, driven by a gas propellant technology (i.e. Freon or a less environmental-damaging HFA).

In 1964 new type of electronic nebulizers were introduced in the form of "Ultrasonic wave nebulizers". Today the nebulizing technology is not only used for medical purpose. Ultrasonic wave nebulizers are for instance also used in humidifier
Humidifier
A humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...

 apparatus, with the purpose to spray out water aerosols to moisten dry air in buildings.

Some of the first models of electronic cigarettes featured an ultrasonic wave nebulizer (having a piezoelectric element vibrating at high-frequency ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...

 waves, to cause vibration and atomization of nicotine
Nicotine
Nicotine is an alkaloid found in the nightshade family of plants that constitutes approximately 0.6–3.0% of the dry weight of tobacco, with biosynthesis taking place in the roots and accumulation occurring in the leaves...

 liquid) in combination with a vapouriser
Humidifier
A humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...

 (build as a spray nozzle
Spray nozzle
A spray nozzle is a precision device that facilitates dispersion of liquid into a spray. Nozzles are used for three purposes: to distribute a liquid over an area, to increase liquid surface area, and create impact force on a solid surface...

 with an electric heating element
Heating element
A heating element converts electricity into heat through the process of Joule heating. Electric current through the element encounters resistance, resulting in heating of the element....

). The most common type of electronic cigarettes currently sold, however chose to omit the ultrasonic wave nebulizer, as it was not found to be efficient enough for this kind of device. Instead the electronic cigarettes now use an electric vaporizer, either in direct contact with the absorbent material in the "impregnated atomizer," or in combination with the nebulization technology related to a "spraying jet atomizer" (in the form of liquid droplets being out-sprayed by a high speed air stream, that passes through some small venturi injection channels, drilled in a material absorbed with nicotine liquid).

Types of nebulizers

The most commonly used nebulizers are Jet nebulizers, which are also called "atomizers". Jet nebulizers are connected by tubing to a compressor
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...

, that causes compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....

 or oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 to flow at high velocity through a liquid medicine to turn it into an aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

, which is then inhaled by the patient. Currently there seems to be a tendency among physicians to prefer prescription of a pressurized Metered Dose Inhaler (pMDI) for their patients, instead of a Jet nebulizer that generates a lot more noise (often 60dB during use) and is less portable due to a heavier weight. However Jet nebulizers are commonly used for patients in hospitals who have difficulty using inhalers, such as in serious cases of respiratory disease, or severe asthma attacks. The main advantage of the Jet nebulizer is related to its low operational cost. If the patient needs to inhale medicine on a daily basis the use of a pMDI can be rather expensive. Today several manufacturers have also managed to lower the weight of the Jet nebulizer down to 635 grams (22.4 oz), and thereby started to label it as a portable device. Compared to all the competing inhalers and nebulizers, the noise and heavy weight is however still the biggest draw back of the Jet nebulizer.

Ultrasonic wave nebulizers were invented in 1964 as a new more portable nebulizer. The technology inside an ultrasonic wave nebulizer is to have an electronic oscillator
Electronic oscillator
An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. They are widely used in innumerable electronic devices...

 generate a high frequency ultrasonic wave, which causes the mechanical vibration of a piezoelectric element. This vibrating element is in contact with a liquid reservoir and its high frequency vibration is sufficient to produce a vapor mist. As they create aerosols from ultrasonic vibration instead of using a heavy air compressor, they only have a weight around 170 grams (6 oz). Another advantage is that the ultrasonic vibration is almost silent. Examples of these more modern type of nebulizers are: Omron
OMRON
is a Japanese electronics company based in Kyoto.Omron was established by Kazuma Tateishi in 1933 and incorporated in 1948. Omron's primary business is the manufacture and sale of automation components, equipment and systems, but it is generally known for medical equipment such as digital...

 NE-U17 and Beurer Nebulizer IH30.

A new significant innovation was made in the nebulizer market around 2005, with creation of the ultrasonic Vibrating Mesh Technology (VMT). With this technology a mesh/membrane with 1000-7000 laser drilled holes vibrates at the top of the liquid reservoir, and thereby pressures out a mist of very fine droplets through the holes. This technology is more efficient than having a vibrating piezoelectric element at the bottom of the liquid reservoir, and thereby shorter treatment times are also achieved. The old problems found with the ultrasonic wave nebulizer, having too much liquid waste and undesired heating of the medical liquid, have also been solved by the new Vibrating Mesh nebulizers. A partial list of available VMT nebulizers includes: Pari eFlow, Respironics i-Neb, Omron
OMRON
is a Japanese electronics company based in Kyoto.Omron was established by Kazuma Tateishi in 1933 and incorporated in 1948. Omron's primary business is the manufacture and sale of automation components, equipment and systems, but it is generally known for medical equipment such as digital...

 MicroAir, Beurer Nebulizer IH50, and Aerogen Aeroneb. As the price of the ultrasonic VMT nebulizers carry a higher price compared to the previous models, most of the manufacturers continue also to sell the more "old fashioned" Jet nebulizer. The most recent innovation in nebulizer technology is the human-powered nebulizer being developed by Dr. Lars E. Olson of Marquette University.

The medical company Boehringer Ingelheim also invented a new device named Respimat Soft Mist Inhaler in 1997. This new technology provides a metered dose to the user, as the liquid bottom of the inhaler is rotated clockwise 180 degrees by hand, adding a build up tension into a spring around the flexible liquid container. When the user activates the bottom of the inhaler, the energy from the spring is released and imposes pressure on the flexible liquid container, causing liquid to spray out of 2 nozzles, thus forming a soft mist to be inhaled. The device features no gas propellant and no need for battery/power to operate. The average droplet size in the mist was measured to a somewhat disappointing 5.8 micrometers, which could indicate some potential efficiency problems for the inhaled medicine to reach the lungs. Subsequent trials have proven this was not the case. Due to the very low velocity of the mist, the Soft Mist Inhaler in fact has a higher efficiency compared to a conventional pMDI. In 2000, arguments were launched towards the European Respiratory Society (ERS) to clarify/expand their definition of a nebulizer, as the new Soft Mist Inhaler in technical terms both could be classified as a "hand driven nebulizer" and a "hand driven pMDI".

Use and attachments

Nebulizers accept their medicine in the form of a liquid solution, which is often loaded into the device upon use. Corticosteroids and Bronchodilator
Bronchodilator
A bronchodilator is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be endogenous , or they may be medications administered for the treatment of breathing difficulties...

s such as salbutamol
Salbutamol
Salbutamol or albuterol is a short-acting β2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease. It is marketed as Ventolin among other brand names....

 (albuterol USAN
United States Adopted Name
United States Adopted Names are unique nonproprietary names assigned to pharmaceuticals marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association , the United States Pharmacopeial Convention , and the American Pharmacists...

) are often used, and sometimes in combination with ipratropium
Ipratropium
Ipratropium bromide is an anticholinergic drug used for the treatment of chronic obstructive pulmonary disease and acute asthma. It blocks the muscarinic acetylcholine receptors in the smooth muscles of the bronchi in the lungs, opening the bronchi...

. The reason these pharmaceuticals are inhaled instead of ingested is in order to target their effect to the respiratory tract
Respiratory tract
In humans the respiratory tract is the part of the anatomy involved with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...

, which speeds onset of action of the medicine and reduces side effects, compared to other alternative intake routes.

Usually, the aerosolized medicine is inhaled through a tube-like mouthpiece, similar to that of an inhaler
Inhaler
An inhaler or puffer is a medical device used for delivering medication into the body via the lungs. It is mainly used in the treatment of asthma and Chronic Obstructive Pulmonary Disease . Zanamivir , used to treat influenza, must be administered via inhaler...

. The mouthpiece, however, is sometimes replaced with a face mask, similar to that used for inhaled anesthesia
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...

, for ease of use with young children or the elderly, although mouthpieces are preferable if patients are able to use them since face-masks result in reduced lung delivery because of aerosol losses in the nose.

After use with corticosteroid, it is theoretically possible for patients to develop a yeast infection in the mouth (thrush
Oral candidiasis
Oral candidiasis is an infection of yeast fungi of the genus Candida on the mucous membranes of the mouth. It is frequently caused by Candida albicans, or less commonly by Candida glabrata or Candida tropicalis...

) or hoarseness of voice (dysphonia
Dysphonia
Dysphonia is the medical term for disorders of the voice: an impairment in the ability to produce voice sounds using the vocal organs . Thus, dysphonia is a phonation disorder...

), although these conditions are clinically very rare. To avoid these adverse effects, some clinicians suggest that the person who used the nebulizer should rinse his or her mouth. This is not true for bronchodilators; however, patients may still wish to rinse their mouths due to the unpleasant taste of some bronchodilating drugs.

Guidelines

Various asthma guidelines, such as the Global Initiative for Asthma Guidelines [GINA], the British Guidelines on the management of Asthma, The Canadian Pediatric Asthma Consensus Guidelines, and United States Guidelines for Diagnosis and Treatment of Asthma each recommend metered dose inhalers in place of nebulizer-delivered therapies.
The European Respiratory Society acknowledge that although nebulizers are used in hospitals and at home they suggest much of this use may not be evidence-based.

Effectiveness

Recent evidence show that nebulizers are no more effective than metered-dose inhalers (MDIs) with spacers and that MDIs may offer advantages in children with acute asthma.

European Respiratory Society highlighted a risk relating to dosage reproducibility caused by selling nebulizer devices separately from nebulized solution. They found this practice could vary dosages 10-fold or more by changing from an inefficient nebulizer system to a highly efficient one.
Two advantages attributed to nebulizers, compared to MDIs with spacers(inhalers), were their ability to deliver larger dosages at a faster rate, especially in acute asthma; however, recent data suggests actual lung deposition rates are the same. In addition, another trial found that a MDI (with spacer) — had a lower required dose for clinical result — compared to a nebulizer (see Clark, et al. other references).

See also

Instead of using nebulizers to deliver a medical liquid to the lungs in the form of aerosol droplets, its also possible to use inhalers or vaporizers for the same purpose.
  • Inhaler
    Inhaler
    An inhaler or puffer is a medical device used for delivering medication into the body via the lungs. It is mainly used in the treatment of asthma and Chronic Obstructive Pulmonary Disease . Zanamivir , used to treat influenza, must be administered via inhaler...

  • Vaporizer
    Humidifier
    A humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...

  • List of medical inhalants
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