Comparative in-vitro Study of the Trachospray, a New Device for Topical Anaesthesia of the Upper Airway

Abstract

Background: Obtaining complete topical anaesthesia of the airway remains a clinical challenge. Particle size is one of the most important variables for the dose deposited and the distribution of aerosols in the airways. The mass median aerodynamic diameter of the particles should be in the range of 5-20 µm. We developed the "Trachospray" as a soft mist spray device for local anaesthetics. This in-vitro comparative test was designed to compare the performance of the new Trachospray device with two existing medical devices. The performance was determined by comparing the spray deposition patterns in the mouth, throat, trachea and lungs. Methods: The human airway was simulated with an artificial idealized mouth and throat model, connected to a Next Generation Impactor. Four measurements were taken for each device (Trachospray, jet nebulizer and a spray pump) with 5.85% NaCl. A fifth measurement was carried out with 0.5% fluorescein solution for a visual inspection of the deposition patterns. The mass median aerodynamic diameter and geometric standard deviation of the droplets were measured. Results: The Trachospray produced an even coverage in the mouth, hypopharynx and vocal cords, with only a small lung fraction. The jet nebulizer produced a much thinner layer coverage of the tongue and surface around the vocal chords with a high lung deposition. The spray pump produced big droplets which deposited mainly at the hypopharynx. Conclusion:The Trachospray device deposits local anaesthetics in the targeted areas for topical anaesthesia of the airway and has promising characteristics for providing effective airway anaesthesia.

Topical Anaesthesia Using a Soft Mist Spray Device Allows Comfortable Awake Visualisation of the Airway via Self-Videolaryngoscopy in Volunteers

“…In our study, participants performed videolaryngoscopy after topical anaesthesia of the airway without additional medication. Previous in vitro investigations using an airway model, specifically the Alberta Idealised Throat connected to a Next-Generation Impactor, demonstrated that the Trachospray soft mist spray device achieved the uniform distribution of local anaesthetics in the mouth, hypopharynx, and vocal cords region [3]. In contrast, currently available topical anaesthesia applicators generate droplets that are either too small, too big or provide inadequate flow patterns [3].…”

“…Previous in vitro investigations using an airway model, specifically the Alberta Idealised Throat connected to a Next-Generation Impactor, demonstrated that the Trachospray soft mist spray device achieved the uniform distribution of local anaesthetics in the mouth, hypopharynx, and vocal cords region [3]. In contrast, currently available topical anaesthesia applicators generate droplets that are either too small, too big or provide inadequate flow patterns [3]. These small droplets result in thin airway coverage but high lung deposition, while larger droplets primarily settle in the hypopharynx.…”

“…Previous studies have demonstrated that the Trachospray soft mist spray device ensures even coverage of local anaesthetics in the mouth, hypopharynx, and vocal cords, and hence, more effective topical anaesthesia [3]. This adequate level of anaesthesia of the upper airway enables a comfortable awake passage through the vocal cords via a flexible bronchoscopy [4].…”

A scintigraphy study of budesonide/glycopyrrolate/formoterol fumarate metered dose inhaler in patients with moderate-to-very severe chronic obstructive pulmonary disease

“…In vitro tests were conducted to demonstrate that the aerodynamic particle size distribution of the radiolabel was the same as that for the micronized drug particles, as determined by in vitro Next Generation Impactor (NGI) tests (model 170, Copley Scientific Ltd., United Kingdom). The NGI is a cascade impactor that measures particle size (range of median diameters for model 170: 0.54 to 11.72 µm at 30 L per minute) by moving particles via an air stream that is forced through a series of 7 nozzles with progressively smaller diameters to produce successively higher velocities [ 18 ]. Radiolabeled MDIs showed no difference in performance relative to that of the non-radiolabeled control MDIs.…”