Development of an Intelligent Spacer Data Logger System

Although delivery of drugs from pressurized metered dose inhalers (pMDIs) via spacer devices is widespread it cannot be assumed that patients take their medication as prescribed or use their spacer appropriately. We developed a Spacer Data Logger device to record patient adherence and whether patients had shaken the pMDI, actuated it soon after shaking, and inhaled a sufficient volume from it.

We report an assessment of the Spacer Data Logger to measure and record that the pMDI was adequately shaken, the time to actuation, and the volume "inhaled" from the spacer up to 26 seconds after actuation. The effect of a delay in actuation following shaking on the dose available for inhalation from the spacer and the effect of a delay in extraction of aerosol from the spacer were assessed using different strengths of beclomethasone dipropionate (50 and 100 μg) and fluticasone propionate (50, 125 and 250 μg).

The volumes measured by the Spacer Data Logger were in close agreement with the reference volumes of four simulated breathing patterns. A delay between shaking and actuating the pMDI resulted in a significant increase in the dose available for inhalation after only 4 seconds for the 50 and 250 μg strengths of fluticasone propionate pMDIs (p = 0.004 and p < 0.001, respectively). A delay between actuation of the drug into the spacer and "inhalation" of aerosol from the spacer also resulted in a steady decline in the dose available from the spacer (p < 0.0001).

These results confirmed the importance of using the pMDI spacer correctly by actuating directly after shaking and inhaling the aerosol from the spacer as soon after actuation as possible to optimize the dose available for inhalation. The Spacer Data Logger should be a useful tool to determine adherence to and "optimum" use of pMDI spacers in patients with asthma and chronic obstructive pulmonary disease (COPD).