Effects of Heat and Humidification on Aerosol Delivery during Auto-CPAP noninvasive Ventilation

Objective: Although, the use of humidification during non-invasive ventilation (NIV) is an important factor in decreasing nasal airway resistance and assuring patient's comfort and adherence; many in-vitro studies recommend switching off the humidifier while delivering aerosol to NIV patients. The aim of the study was to in-vivo determine the effect of humidification on salbutamol delivered via different inhalation devices to chronic obstructive pulmonary disease (COPD) patients using automatic continuous positive airway pressure (Auto-CPAP). Method: Aerosol delivery to NIV COPD patients by Aerogen Solo vibrating mesh nebuliser (VMN), Jet nebuliser (JET) and a metered dose inhaler (MDI) with AeroChamber MV spacer (AC) were compared with and without humidification. Auto-CPAP was adjusted at non-invasive ventilation mode with the integrated heated humidifier (IHH), as a source of humidity. The heater was set to the default setting 3, equivalent to 50ºC. Urine samples, 30 minutes and 24 hours post inhalation, as an index of the relative pulmonary and systemic bioavailability respectively, were provided by subjects and aliquots were retained for salbutamol analysis using solid phase extraction and high performance liquid chromatography (HPLC).