Is Combihaler usable for aerosol delivery in single limb non-invasive mechanical ventilation?

Combihaler could connect both pressurized-metered-dose-inhaler (pMDI) and nebulizers to non-invasive-ventilation-circuit (NIV). This can be used to give the patient preliminary-bronchodilator-dose in an attempt to increase forced-expiratory-volume-in-one-second (FEV1) before nebulization. It was proven effective in dual-limb-ventilation.The aim of this study was to compare aerosol-delivery by Aerogen-Solo-vibrating-mesh-nebulizer (SOLO) using its standard-T-piece and Combihaler with and without pMDI in single-limb-NIV.Each device was placed in single-limb-NIV proximal to breathing-simulator set at 15breaths.min−1, Tidal-volume = 500 mL and 1:3 inspiratory-expiratory-ratio. 2 ml respirable-solution containing 10000 μg-salbutamol was nebulized using SOLO with three connection-setting; I:T-piece, II:Combihaler and III:Combihaler-with-pMDI. Only with connection-III, two pMDI-doses, containing 100 μg-salbutamol each, were actuated before nebulization of 2 ml of salbutamol-solution. Fate of nebulized-dose and aerodynamic-characteristics were determined.Percentages of nominal-dose of total-inhalable-dose (TID) of both Combihaler-connections (II&III) were slightly greater than those of T-piece. Combihaler with pMDI (connection-III) had significantly-greater fine-particle-dose (FPD) and mass-median-aerodynamic-diameter (MMAD) than both T-piece and Combihaler with p-value = 0.008 and 0.010, respectively for FPD and p-values = 0.004 and 0.025, respectively for MMAD.Similar to dual-limb-ventilation, Combihaler work efficiently for aerosol-delivery in single-limb-NIV. The relatively higher FPD of Combihaler suggests that having large-volume-spacer in single-limb-NIV could save some aerosol from condensation. Also, combining nebulizer-with-pMDI on the same connection may provide great clinical-benefits through pre-bronchodilation.

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