[Teaching the inhalation manoeuvre to asthmatic children by means of visual feedback].

Background: For inhalation as a mainstay of asthma therapy, the correct inhalation technique is of utmost importance. This comprises not only the correct handling of the device but also specific device-dependent requirements concerning the inhalation manoeuvre itself.

Methods: We examined whether totally different inhalation manoeuvres can be educated in parallel in asthmatic children. As target manoeuvres we defined: 1) an inhalation as fast as possible (peak inspiratory flow >or= 60 l/min) with high acceleration in the starting phase as it is normally required for dry powder inhalers. 2) A constant inhalation at a flow between 40 and 90 l/min with a long duration as it is regarded to be optimal for propellant driven systems. As models for dry powder inhalers the Diskus (Accuhaler, a medium resistance device) and the Turbuhaler (high resistance) were chosen. As an example of a propellant-driven we used the Autohaler (breath-actuated MDI). A total of 52 outpatients (age 4 to 14 years) with asthma were educated two times. We measured peak inspiratory flow (PIF), duration of inspiration with inspiratory flow >or= 30 l/min (Ti30), inspiratory volume (Vol) and acceleration of inspiratory flow (mPIF) through the devices in random order before and after each training session. Measurements were performed using the inhalation manager, a computer based spirometry system, which allows recording of inspiratory manoeuvres through Placebo inhalers by means of a pneumotachometer. Results are immediately visualized (optical feedback) and evaluated.

Results: Training children simultaneously with different inhalation systems appeared to be difficult. Only for the DPIs a significant increase of children inhaling in the pre-given target area could be reached. With Diskus, the rate of correct manoeuvres increased from initially 57.7 % to 88.5 % after training and with Turbohaler from 32.7 % to 65.4 %, respectively. With MDI, this rate increased only from 32.7 % to 42.3 %. This indicates that a high inspiratory flow may be easier to be learned than a constant slow inhalation, at least when training is done simultaneously in children.

Conclusions: Thus, training of the different inhalation manoeuvres for DPI and MDI should be performed separately. When prescribing inhaled drugs for reliever treatment and maintenance therapy for any individual patient, prescribers should select inhalation devices, which can be used in a similar way without clinical disadvantage.