Aerogen Nebuliser Versus Standard Nebulised Therapy in Acute Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease presents a significant burden on Emergency Departments and acute medical services, accounting for approximately 90,000 hospital admissions a year, with an average stay lasting 11 days. COPD accounts for 10% of acute hospital admissions, therefore any method of improving health outcomes and reducing the burden on acute services will benefit patients twofold.

Severity of acute COPD is based on clinical indicators such as patient perceived breathlessness, arterial blood gas analysis and respiratory rate. Although breathlessness is a subjective marker, multiple scoring systems have been devised in an attempt to standardise this in order to see an objective improvement in the patient. One of the most commonly used and repeatedly validated scoring systems is the BORG score, which has been shown to effectively demonstrate improvement in breathlessness in the emergency setting .

Nebulised bronchodilator therapy is the mainstay of treatment, as described in the National Institute of Clinical Excellence guidelines. Delivery of bronchodilators (salbutamol and ipratropium) is through a standard facemask - in this Trust it is a Phillips Respironic© mask. Drugs delivery is variable through a nebuliser mask and it is difficult to measure exactly how much of the drug is being delivered to the more distal bronchial tree. Furthermore, this can be highly variable between patients depending on how well the mask fits and patient tolerance, amongst other factors.

Various attempts have been made to improve drug delivery in acute setting such as a spacer and a hood (within paediatric asthmatic patients) , . However, they have all showed that the clinical outcomes are the same regardless of the method of delivery.

Clinical assessment is based on a combination of objective and subjective parameters. Within the Emergency Department, these include both patient and clinician perception of improvement in symptoms (primarily shortness of breath). Assessment also includes more objective measurements such as oxygen saturation, arterial blood gas measurements and end tidal CO2 measurements when available.

There are many challenges that we face specifically within the Emergency Department with patients with COPD. As we are seeing patients as soon as they enter the hospital, initial therapy may have already been administered by the ambulance service so any assessment will be slightly biased and the patient may initially appear better than they actually are. Furthermore, there are often burdens on Emergency Departments during busy periods during the winter, meaning it is not always possible to give patients instant treatment or to be seen immediately by a doctor, particularly if there are more unwell patients based on the triage system.

In addition, some of the more objective measures used in previous trials such as bedside spirometry are not practical in the Emergency Department for several reasons. Firstly, when a patient is acutely short of breath they will not be able to perform spirometry properly. Secondly, as this is not something done routinely in the Emergency Department, both doctors and nurses may not be properly trained to carry this out and we may obtain falsely high or low results.

The Aerogen Aeroneb Solo© is a new nebuliser which is hypothesised to increase drug delivery to peripheral bronchi. Previous studies have showed that it delivers up to 4 times more drug than jet nebulisers and up to 3 times as much as metered dose inhalers. However, this will be its first study with the adapter in human subjects and its first study specifically for COPD.