From the authors:
- 1Royal Brompton Hospital and Imperial College, London, and 2Royal Alexandria Hospital, Brighton, UK.
- A. Bush, Dept of Paediatric Pulmonology, Royal Brompton Hospital and Imperial College, London, SW3 6NP, UK. E-mail: a.bush{at}rbh.thames.nhs.uk
We thank S.I. Fuchs and M. Gappa for their interest in our review 1. The points they make are of general importance. As with all lung function measurements, lung clearance index (LCI) must be measured with equipment that has adequate frequency responses, precision and stability, and has been suitably calibrated. Their work with an ultrasonic flow meter is welcome, because it has been compared with a gold standard, and may make measurement of LCI more accessible. The use of equipment which has not been so carefully validated must be firmly discouraged.
Statement of interest
None declared.
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