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Editor,—The study by Iles et al 1 may, once and for all, help dispel the myth that aerosol delivery to the lungs of crying children is enhanced as a result of them taking a deep inspiratory breath.
Compelling evidence that delivery of drug to the lungs of distressed infants is greatly reduced compared with that to the lungs of a relaxed tidal breathing infant has been available for many years. Murakamiet al 2 illustrated this point extremely effectively in a radiolabelled deposition study using a jet nebuliser, while Tal et al 3also observed a tenfold reduction in dose in crying infants using a pMDI and Aerochamber. More recently we have also reported significantly reduced drug delivery and increased treatment times in the small minority of young children who were upset when using the dosimetric Halolite nebuliser.4
There are two principal reasons for poor delivery in distressed children. Failure to achieve a good seal between mask and face when using a face mask results in air entrainment with little or no drug being inhaled.5 Even if a face mask can be clamped on to the face of a distressed child, the dose inhaled is reduced and the majority of the inhaled dose deposits in the upper airways, to be swallowed as illustrated so elegantly in the paper by Murakamiet al. This is due to the abnormal breathing patterns adopted by upset toddlers and infants.6
As asthma nurses have known for many years, factors relating to the use of devices by patients are of greater importance in determining drug delivery to the lungs than are technical factors such as static in holding chambers which is only one of many sources of variability.7 To date, pharmaceutical companies and nebuliser manufacturers have conspicuously failed to develop devices that are intrinsically acceptable to young children. It is to be hoped that consideration of factors that would positively encourage young children to cooperate will be incorporated into the next generation of delivery systems.