Assessment of the effects of vibrating mesh nebulisation versus jet nebulisation on the electrical activity of the muscles involved in breathing (neural respiratory drive), breathing mechanics (respiratory impedance measured by forced oscillation technique), respiratory flow, heart rate and rhythm, spirometry and breathlessness symptoms in patients with chronic obstructive pulmonary disease who require non-invasive ventilation.

Background Chronic obstructive pulmonary disease (COPD) remains a leading cause of morbidity and mortality in the United Kingdom. Acute exacerbations of COPD (AECOPD) frequently necessitate hospitalisation, with standard treatment comprising nebulised bronchodilators, antibiotics, and systemic corticosteroids. Approximately 20% of patients hospitalised with AECOPD require non-invasive ventilation (NIV) to manage decompensated hypercapnic respiratory failure, often necessitating concurrent administration of nebulised therapy.

Home NIV use is increasing among COPD patients to improve respiratory symptoms, quality of life, reduce hospitalisation frequency, and enhance survival. These patients may also require nebulised bronchodilator therapy during NIV, particularly when managing acute exacerbations not severe enough to warrant hospitalisation.

Currently, two nebulisation modalities are used as standard of care for patients on NIV:

Jet nebulisation (JN) - the conventional delivery method Vibrating mesh nebulisation (VMN) - a newer technology that utilises a mesh membrane oscillating at high frequency to produce drug-carrying droplets of predetermined size

VMN has been developed to optimise drug delivery in various patient populations, including those who are spontaneously breathing, receiving invasive mechanical ventilation, or on NIV. This technology is designed to enhance pulmonary drug deposition while minimising residual drug volume post-nebulisation.

Previous research has demonstrated that VMN achieves superior pulmonary drug deposition during NIV compared to JN in both healthy subjects and stable COPD patients. VMN has also been shown to produce greater improvements in forced expiratory volume in one second (FEV₁) among hospitalised patients. However, the comparative effects of these nebulisation methods on physiological parameters such as neural respiratory drive and respiratory system impedance during NIV in COPD patients with chronic respiratory failure remain unexplored.

Study Objective This pilot randomised crossover trial aims to compare the physiological effects of vibrating mesh versus jet nebulisation of salbutamol during NIV in patients with chronic respiratory failure due to COPD.

Methods Study Design A randomised crossover trial with participants receiving both interventions with a 48-hour washout period between treatments.

Participants We will recruit 12 patients with COPD currently receiving NIV under the care of the Lane Fox Unit. All participants will provide written informed consent prior to study procedures.

Procedures

Following consent, we will record baseline data including:

NIV settings Anthropometric measurements Arterial blood gas analysis Clinical observations

Participants will be randomised to receive salbutamol via either VMN or JN during NIV. We will measure the following parameters at multiple time points within one hour after nebulisation:

Neural respiratory drive via parasternal electromyography Spirometry Respiratory impedance (mechanics of breathing)

Participants will self-report breathlessness using both a numerical scale and a validated scale.

After a minimum of 48-hour washout period, participants will return to repeat the protocol with the alternative nebuliser type.

Inclusion Criteria:

• Patients with COPD receiving home non-invasive ventilation for chronic respiratory failure under the Lane Fox Respiratory Service at Guy's and St Thomas' NHS Foundation Trust
• Tolerating home non-invasive ventilation for at least 4 hours/24 hours
• Aged 18-80 years old
• Able to communicate symptom burden to the research team
• Able to give informed consent for participation in the study
• Clinical stability, with no acute exacerbations of COPD for 2 weeks prior to enrolment

Exclusion Criteria:

• Severe, non-respiratory organ dysfunction including, but not limited to:

  • Congestive cardiac failure
  • Significant cardiovascular disease
  • End-stage malignancy
  • End-stage renal failure

• Acute pulmonary pathology requiring emergency treatment including, but not limited to:

  • Pneumonia
  • Pneumothorax
  • Pulmonary embolism

• Severe cognitive impairment

• Psychosocial factors that would preclude completion of the study protocol

VMN and JN are easily distinguishable due to both their visible and audible signatures. It is therefore not feasible to blind the patient to the delivered intervention. The mode of nebulisation will be known to both the investigator and participant, and the absence of masking is acknowledged to be a potential source of bias. Analysis of NRD and spirometry will be masked as an offline analysis.