The Role of Gas Flow in Transnasal Pulmonary Aerosol Delivery: A Double-blinded, Randomized Controlled Trial
Condition: COPD Asthma
Study type: Interventional

Summary: 
      Aerosol delivery via nasal cannula has gained increasing popularity, due to its combined
      benefits from aerosolized medication and heated warm oxygen therapy. In our previous in vitro
      study, we investigated the effects of the ratio of nasal cannula gas flow to subject's peak
      inspiratory flow (GF: IF) on the aerosol lung deposition, and we found that aerosol
      deposition in lung increased as the GF: IF decreased with an optimal GF: IF between 0.1 to
      0.5 producing a stable "lung" deposition in both quiet and distress breathing. Thus we aimed
      to further validate such an optimal GF: IF in patients with reversible airflow limitations by
      the delivery of bronchodilators. Adult COPD or asthma patients who met ATS/ERS criteria for
      bronchodilator response in pulmonary function lab will be recruited and consented. After a
      washout period (1-3 days), patients will receive an escalating doubling dosage (0.5, 1, 2,
      and 4mg) of albuterol in total volume of 2mL, delivered by mesh nebulizer via nasal cannula.
      Patients will be randomly assigned to inhale bronchodilator into 3 group using different
      flows: 50 L/min,GF: IF = 1.0, and GF: IF = 0.5.
    

Detailed description: 
      Introduction Both in vitro and in vivo radiolabeled studies on nebulization via high flow
      nasal cannula (HFNC) showed that aerosol lung deposition decreased with the increasing nasal
      cannula gas flow, which, however, was not observed in patients with distressed breathing. In
      our previous in vitro study, we investigated the effects of the ratio of nasal cannula gas
      flow to subject's peak inspiratory flow (GF: IF) on the aerosol lung deposition, and we found
      that aerosol deposition in lung increased as the GF: IF decreased with an optimal GF: IF
      between 0.1 to 0.5 producing a stable "lung" deposition in both quiet and distress breathing.
      Thus we aimed to further validate such an optimal GF: IF in patients with reversible airflow
      limitations by the delivery of bronchodilators.

      Methods and analysis COPD and asthma patients with positive response to four actuations of
      albuterol via metered dose inhaler (MDI) and valved holding chamber (VHC) will be enrolled
      and consented in the study. After a washout period (1-3 days), patients will be randomly
      assigned to three groups with different nasal cannula gas flow: 50L/min, GF: IF = 1.0, and
      GF: IF = 0.5. In each treatment arm, patients will firstly receive saline, then followed by
      an escalating doubling dosages (0.5, 1, 2, and 4mg) of albuterol in a total volume of 2mL,
      delivered by mesh nebulizer (VMN, Aerogen, Ireland) via heated nasal cannula at 37℃. An
      interval of 30 min will be maintained between two doses of albuterol, and pulmonary
      spirometry will be measured at baseline and after each dose. Titration will be terminated
      when an additional FEV1 improvement was < 5%.
    

Intervention name(s): nasal cannula gas flow
Intervention type(s): Other
Intervention description(s): High flow nasal cannula (HFNC) is a relatively new oxygen device, which provides warmed and humidified oxygen for patients. When patients need to inhale aerosolized medication during HFNC, the nebulizer will be placed in-line in order to provide both treatments. This study will investigate the influence of three flow settings (50 L/min, GF:IF=1, GF:IF=0.5) on the clinical effects of nebulization.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Care Provider)
Primary purpose: Treatment
Keywords: Nasal cannula; Aerosol therapy; Gas flow