[Inhalation therapy for asthma in children. Questions about effectiveness]

A better understanding of childhood asthma, a disease affecting 6 to 10% of the paediatric population, has led to the development inhalation systems which can provide undeniably effective therapy but also raise a certain number of questions as to the quantity of drug actually reaching the pulmonary airways. When aerosols, the reference system, are used with a good inhalation technique, as much as 80% of the active product goes no further than the oral cavity, only 10% reaching the intrapulmonary airways. In addition, the system requires a co-ordination between hand movements and inspiration which is beyond the capacity of children under 7 or 8 years of age. Doses and granulometric flow also vary greatly depending on the propulsion gas. Inhalation chambers mounted on face masks avoid the problem of co-ordinated movements, increasing pulmonary deposition, but real drug delivery in infants who breathe through the nose remains to be determined. Systems which deliver the drug in the form of a powder have also been developed. With these devices, the product is held in a chamber together with carrier particles and is inhaled as inspiration creates air turbulence in the chamber. Minimal inhalation peak is the limiting factor. Nebulizers offer another possibility since no voluntary control of respiration is required, the child breathes at his own rhythm. The drug is nebulized either by a forced air or ultrasound system. Such systems may be very useful for infants but are usually not adapted for toddlers or older children. Despite the lack of precision as to the quantity of drug actually delivered to the pulmonary airways, the use of inhalations has completely changed the quality of life of children with chronic asthma. Further progress will be made through a better understanding of the two most important factors: the child and corticosteroids. Indeed, the child's co-operation (or non-co-operation) is one of the major sources of (un)successful treatment: even the best inhalation system can have little impact on the disease if it is not accepted and used correctly by the child.