The Airsonett temperature-controlled laminar airflow device for persistent allergic asthma

CE marking

The Airsonett device is a class I medical device for which the manufacturer, Airsonett AB, received a CE mark in June 2010.

Description

The Airsonett device is a temperature‑controlled laminar airflow device intended to be used as an add‑on to standard treatment for people whose asthma is affected by exposure to airborne allergens, particularly those with severe persistent allergic asthma. It was previously marketed under the name Protexo, and may also be referred to as Airsonett Airshower. All of these names refer to the same model of the device.

The device consists of a base unit containing an air intake, filter and cooler, neck pipes, and an air supply nozzle. The base unit stands next to the patient's bed and the air supply nozzle is positioned above their head.

The device is principally designed to operate by the bedside while the patient sleeps. The device draws air from the room through a filter that captures allergens and other particles. This filtered air is then cooled to 0.5–0.8ºC below the ambient room temperature, before being slowly expelled from the air supply nozzle. This cooler air is more dense than the ambient room air and so it descends into the patient's breathing zone. The device provides cooled, filtered air around the patient's face through the night, breaking the natural body convection without creating draught or dehydration. The manufacturer describes this as the key feature that differentiates the Airsonett device from other devices designed to supply filtered air to the breathing zone.

Intended use

The device is designed to reduce the level of allergens inhaled during the night. It does this by providing a temperature‑controlled laminar flow of filtered air, thereby alleviating the symptoms of allergy‑induced diseases.

Setting and intended user

The Airsonett is primarily intended for home use by people with poorly controlled persistent allergic asthma despite high‑intensity treatment. Such patients are typically described as having reached Step 4 of the Global Initiative for Asthma (GINA) and the British Thoracic Society/Scottish Intercollegiate Guidelines Network (BTS/SIGN) guidelines. This is defined as having poor control of asthma symptoms despite treatment with moderate doses of inhaled steroid and add‑on therapies. These patients can be further defined as having an Asthma Control Test (ACT) score of less than 18. The ACT provides an indication of how well a person's asthma has been controlled over the previous 4 weeks; scores range from 1 to 25, with any score below 20 indicating poor symptom control. Such patients are likely to be under the care of a hospital‑based respiratory physician as well as receiving regular primary care management. The device may also be considered for people with less severe conditions such as rhinitis and eczema, although these uses are outside the scope of this briefing.

Current NHS options

The Airsonett device is intended to be used for people who are at Step 4 or above of the BTS/SIGN stepwise treatment approach. The 2012 BTS/SIGN guidelines recommend that add‑on therapies can be considered for people who have reached Step 5, which means that continuous or frequent use of oral steroids is often necessary to control asthma symptoms.

Current add‑on treatment options for severe allergic asthma as recommended in the NHS are daily corticosteroid tablets and omalizumab. Other available options include bronchial themoplasty and immunosuppressants such as methotrexate and ciclosporin.

Omalizumab for treating severe persistent allergic asthma (NICE technology appraisal guidance 278) recommends omalizumab as an optional add‑on to standard therapy in people aged 6 years and older who need continuous or frequent treatment with oral corticosteroids.

Bronchial thermoplasty uses short pulses of radiofrequency energy to reduce the amount muscle in the airway. Bronchial thermoplasty for severe asthma (NICE interventional procedure guidance 419) states that the procedure shows some improvement in symptoms of severe asthma, including expiratory flow rate, beta‑2 antagonist use, and number of exacerbations and hospital admissions. There is also evidence of improvement in quality of life. The guidance goes on to state that although the evidence on short- and medium‑term safety are adequate, more evidence is needed on longer‑term safety. Therefore, bronchial thermoplasty should be used only with special arrangements for clinical governance, consent and audit or research, and patients should be chosen by a respiratory team with special expertise in managing severe asthma.

Treatment with immunosupressants can decrease long‑term steroid tablet requirements, but these drugs have significant adverse effects. As most immunosuppressants act non‑selectively, a common treatment effect is immunodeficiency, which results in increased susceptibility to infections.

NICE is aware of the following devices that appear to fulfil a similar function to the Airsonett:

NICE has not investigated the regulatory status of these devices; it is the responsibility of healthcare professionals to check this status for any intended use.