Early High-flow Oxygen Therapy With nebuLized Beta-2-agonist Using a Vibrating Mesh for the Management of Moderate to Severe Asthma Exacerbation in the Emergency Department

Acute exacerbation of asthma represents an acute or sub-acute worsening in symptoms and lung function in patients with asthma. It is characterized by a progressive increase in symptoms of shortness of breath, cough, wheezing, or chest tightness. It is a common diagnosis in patients admitted in an Emergency Department for dyspnoea. Near 10 to 15% of respiratory symptoms in an ED are related to acute exacerbation of asthma.

Treatment of acute exacerbation of asthma associates nebulized beta-2 agonist adrenergic with or without ipratropium bromide, oral corticosteroids and controlled oxygen therapy to maintain SpO2 between 93 and 95%. Treatment in the ED did not vary during last years, including for patients with a lack of efficacy after first line treatment, and exacerbation are always associated with a hospitalisation in 40% of adult patients and with mortality in 1% of hospitalized patients.

Vibrating mesh nebulizers are devices using vibration to push drug through the mesh, resulting in the drug nebulization. Vibrating mesh nebulizers have been associated with better pulmonary drug delivery than jet-nebulizers, provide faster improvement in peak expiratory flow and have been associated in retrospective studies with patient prognosis, particularly in terms of throughput time and need for hospitalisation. However, no studies have prospectively compared nebulisation with a vibrating membrane device with standard nebulisation in patients with asthma exacerbation on clinically relevant criteria. Nebulisation with a vibrating membrane device may potentiate the clinical efficacy of short-acting bronchodilators, result in faster and more effective clinical improvement, and be associated with improved short- and medium-term patient outcomes.

High-flow nasal cannula heated, and humidified oxygen (HNFO) is a ventilatory support which is commonly used for the management of acute respiratory failure for acute respiratory failure in intensive care units and in emergency departments. HFNO delivers high fraction of inspired oxygen (FiO2), generates a low level of positive pressure and provides washout of dead space in the upper airways, thereby improving mechanical pulmonary properties and unloading inspiratory muscles during ARF. Consequently, HFNO is associated with a decrease in the work of breathing. During asthma exacerbation, HFNO was associated with an improvement in the dyspnea level and in the respiratory rate compared with conventional oxygen therapy. However, HFNO has never been assessed in association with nebulized beta-2 adrenergic agonist.

To resume, beta-2 adrenergic agonist nebulization with a vibrating mesh nebulizer seems effective, especially compared to standard jet nebulization. In addition, HFNO is a technique that appears to be suitable for the pathophysiological conditions of chronic reversible respiratory failure, and can be used during exacerbations of asthmatic disease. The high flow rate of gas makes it possible to control the FiO2 in order to avoid hyperoxia, to generate a PEEP effect, to reduce the patient's work of breathing and the respiratory resistance, and to avoid the re-inhalation of CO2 by a dead space wash-out.

In the EOLE study, the investigators propose to compare three therapeutic management strategies. One standard strategy (nebulisation with a jet-nebulizer), and two experimental strategies (nebulisation with a vibrating mesh device, and nebulisation with a vibrating mesh device in association with HFNO).

The investigators hypothesise that bronchodilator nebulization with a vibrating mesh nebulizer is more effective than jet-nebulizers for the management of patients admitted for asthma exacerbation and non-responders or with lack to efficacy to initial treatment. Furthermore, the investigators also hypothesise that the addition of the physiological effects of HFNO may enhance the efficacy of the treatment.

The therapeutic effects of nebulisation with a vibrating membrane device alone or with the addition of the physiological effects of HFNO could constitute a new approach to the management of asthma patients, particularly in patients who are insufficiently responsive or non-respondent to initial treatment.