Background: For patients with severe chronic obstructive pulmonary disease under invasive mechanical ventilation, medication for aerosol therapy is delivered through tracheostomy or endotracheal airways. Typically, these medications (such as bronchodilators) are long-acting formulations that are delivered through Soft Mist™ Inhalers (SMI), or Pressurized Metered-Dose Inhalers. The Respimat® SMI has been shown to have increased efficiency because of its slow and prolonged aerosol mist and has gained popularity in clinical settings. However, the Respimat was not designed for drug delivery through artificial airways. Therefore, there is a need for SMI adapters in intensive care for use in mechanical ventilator circuits. The purpose of this study was to evaluate the performance of a new Respimat adapter (ODAPT™ for mechanical ventilator [ODAPT MV]) for use in mechanical ventilator circuits which, in combination with a Pulmodyne T-piece adapter, allows use without interruption of the circuit in case of medication replacement. Methods: Tiotropium delivery to the lungs, using Respimat, was assessed using the ODAPT MV adapter within an in vitro setup, including a three-dimensional printed trachea model and a mechanical ventilator. Medication deposition and losses were investigated using two commonly used tracheostomy tube (TT) sizes (6 and 8 mm inner canula) for two flow rates (45 and 60 L/min) under different conditions (30%-50%. and 100% relative humidity [RH]). Medication delivery using the ODAPT MV adapter was compared with the RTC-26C in-line adapter under similar conditions (8 mm TT size, 100% RH at 45 L/min). Results: It was found that 7.1%-13.4% of the nominal dose (ND) was lost in the ODAPT MV adapter for different TT size, RH, and flow rates used. Higher losses were found in the inhaler's mouthpiece ranging from 15.7% to 29.1% ND. The percentage of the delivered medication reaching the lungs was determined to be 13.7%-18.5% ND delivered without significant differences between the experimental conditions tested. The ODAPT MV performed well compared with the RTC-26C under similar conditions (17.9% and 16.6% ND, respectively). Conclusion: The medication delivered through mechanical ventilation using the ODAPT MV adapter represents about one third the dose delivered directly through the Respimat SMI in vivo.
Keywords: ODAPT MV adapter; Spiriva Respimat; mechanical ventilation; soft mist inhaler; tracheostomy tube.