High-humidity nasal cannula (HFNC) has been shown to be effective in improving oxygenation and avoiding intubation in multiple randomized control trials, it is also suitable and feasible for long term use. Aerosol delivery via HFNC will minimize interruptions and improve patient compliance, bench study and radionuclide imaging study done in healthy volunteers demonstrated that aerosol can be effectively delivered using HFNC. This study aims to evaluate the efficacy of bronchodilator delivered via HFNC in chronic pulmonary obstructive disease or asthma patients.

Chronic obstructive pulmonary disease or asthma patients who have positive response in bronchodilator test will be consented and enrolled, patients come back for the second bronchodilator assessment within one to three days after the initial bronchodilator test. Albuterol with different concentration will be provided to the patients via HFNC, patients will be assessed by spirometry after each concentration until bronchodilator response is positive and does not improve after the next dose.

Inclusion Criteria:

• Diagnose with COPD or asthma
• Bronchodilator test is positive (According to ATS guidelines, FEV1 change from initial more than 12% and FEV1 absolute change more than 200 mL);
• Age > 18yrs and < 90yrs

Exclusion Criteria:

• Recent pulmonary exacerbation

• Mental disease

• Uncooperative

• Reluctant to participate

• Patients who are unable to come back to get the second spirometry within three days

• Contraindicated to Albuterol (Ventolin, GSK)

  • Rest HR > 100 beats/min
  • Serum K+ < 2.8 mmol/L