Monitoring k-valve Latching Performance using High-Speed X-Ray Imaging

A.P. McKiernan


It is well known that drug delivery into the lungs is highly dependent on a patient’s inhaler technique. Failure to co-ordinate actuation with dose inhalation from pressurised Metered Dose Inhalers (pMDIs) is often a barrier to correct dose administration. Dry Powder Inhalers (DPI’s) do not need such coordination of actuation and inhalation but require forceful inhalation which many patients fail to achieve [1].

Breath triggered inhalers (BTI) have been developed to help these problems. The k-haler® is a breath triggered inhaler with a unique mechanism of dose delivery based on a kinked valve design, dosing being initiated by patient breath inhalation. The device is easy to use, activated with a low inspiratory force and emits a gentle plume making it suitable for patients who have difficulty with producing high inspiratory force needed for DPIs [2, 3].

The k-haler has evolved since the initial concept design and now incorporates a dose counter and bespoke mechanism to accommodate canister height variability resulting from the canister crimping process. The k-valve® mechanism is a kinked tube acting as a holding chamber.  Latching of the kinked k-valve component occurs as the mouthpiece is opened and is important for placing the holding chamber into a closed state so that the dose is retained. The mechanism unlatches the k-valve under a low inspiratory flow rate, the tube unkinks, and the dose is delivered into the lungs.

A high-speed phase-contrast X-Ray imaging technique was employed at a synchrotron facility to monitor, diagnose and resolve latching performance and the results have enabled comparison of real internal device motion to theoretical expectation. The technique is significantly faster and more sensitive than industrial CT scanning. This work has led to design enhancement to increase latching margin and further improve overall performance.

Key Message

High-speed phase contrast X-Ray imaging enables quantification of dynamic angles and displacements and has been used as part of k-haler development programme to optimise latching performance and to enable comparison of real internal device motion to theoretical calculation

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