The clinical course of cystic fibrosis is characterised by pulmonary involvement with mucus retention, chronic pulmonary infection and parenchymal inflammation. Recurrent infectious exacerbations are usually accompanied by a fall in lung volumes. This pilot study investigated whether exacerbations can be detected early by daily spirometry. Ten patients with cystic fibrosis (5 female; 5 male; mean age 24.9 years) performed daily spirometry using a portable transtelephonic spirometer (Spirophone). Infectious exacerbations were diagnosed on clinical grounds and treated without knowledge of the spirometry results. Data of 9 patients recorded over a period of 5-11 months were analysed. One patient was excluded due to non-compliance. A total of 20 infectious exacerbations occurred during the observation period. A fall of at least 20% in one or more of the following parameters was observed in 90% (18/20) of exacerbations: FVC, FEV1, PEF, and FEF25/75. A daily drop in lung volumes of 0.7% to 1.2% was recorded beginning at a median of 33 (20 to 120) days before infectious exacerbations were diagnosed. There was a 2-3% daily improvement in spirometric data under treatment with antibiotics.
Conclusion: Daily spirometry allows early recognition of pulmonary infectious exacerbations in patients with cystic fibrosis. Daily spirometry may be used as an indicator for early antibiotic treatment.