New mechanical aid to physiotherapy in cystic fibrosis.

The force of impact and frequency of percussion by physiotherapists and parents 
of children with cystic fibrosis were analysed on a special test 
rig and incorporated in a prototype percussor. In adult volunteers and 
cadavers a maximum intrathoracic pressure could be achieved by a critical 
frequency of mechanical percussion which was higher than that reached by 
physiotherapists and parents. Consequently the percussor was redesigned to operate at 
this optimum frequency. It was then discovered that if the percussor 
was pressed firmly enough against the chest, this maximum intrathoracic pressure 
could be indicated by quivering of the voice. In a continuing 
study of intrathoracic pressures obtained mechanically and manually the Salford percussor's 
produced higher pressures than the physiotherapists' and maintained them constantly, while 
the physiotherapists' efforts and results varied from one to another. Hospital 
and domiciliary use of the percussor have shown it to help 
in the first stage of the physiotherapy routine for patients with 
cystic fibrosis. The percussor should enable adolescents and adults to treat 
themselves and encourage twice-daily and more effective chest treatments. It is 
easy to apply and its speed and efficiency should enable parents 
to improve the quality of their chest therapy for younger children 
at home. Its long-term benefits are difficult to assess because of 
the nature of the disease. 