Respiratory diseases (asthma, cystic fibrosis, COPD…) need for the diagnosis and the follow-up the use of pulmonary function tests. These technics which are used since the nineteenth century and their discovery by Hutchinson, are now currently performed in pediatrics hospitals but they require trained personnel. Spirometry can be a difficult technic, especially for children. The accuracy and repeatability depend on many factors: equipment, patient effort, supervision and encouragement of a technician. A longitudinal follow up of measures can be good especially in pediatric populations, where children have generally more difficulties recognising their symptoms.

Cystic fibrosis is a severe genetic chronic disease, that affects 1/4500 birth in France.

It's a multi system disease that affects the respiratory system, with a decline in lung function over the time and consecutive to pulmonary exacerbations, the digestive system (malabsorption of fat and vitamins) and the endocrine system (diabetes).

Pulmonary function is an important clinical indicator of the health of individuals with cystic fibrosis.

Close monitoring of patient health with daily recording of physical measurements and symptoms didn't have a negative impact, home spirometry function test could help detect earlier a decline of the lung function and pulmonary exacerbations.

Frequent exacerbations are associated with morbidity, mortality, accelerated decline in lung function and a decreased quality of life. They are also a major driver of health costs.Their early detection is a goal.

Children with cystic fibrosis have more difficulties recognizing symptoms of exacerbations.

Few studies in pediatric showed a good observance in realizing home spirometry, especially in young patients and those living far from the hospital and with a good satisfaction.

Daily monitoring of lung function is probably too tedious for children who already have lots of medication.

Medical adhesion of adolescent's patients is often suboptimal, compared with younger patients. But it's during this period that the decline of the respiratory function is the most important, with its principal cause: pulmonary exacerbations. Frequent home pulmonary function test is possible and can improve medication adherence without adding too much time, but there was no change in the decline of the FEV1 and the number of pulmonary exacerbations.

The association of home monitoring of lung function and a symptom questionary (cough, sputum and dyspnea) can predict exacerbation with a good specificity and sensibility.

The Mir Spirobank Smart is a bluetooth connected device, permitting patients to realize spirometry at home with a smartphone.

The accuracy of the Spirobank Smart compared with a spirometry in a hospital showed a good correlation (asthma and COPD population), if it's used by trained personnel.

The aim of this study is to determine the feasibility of a home respiratory monitoring in a pediatric cohort of patients with cystic fibrosis and the satisfaction of the kids, the parents and the team of the CRCM.

Inclusion Criteria:

• Patients with a cystic fibrosis diagnosis confirmed by a sweat chloride measurement ≥ 60 mmol/L
• Age between 10 and 20 years at enrolment
• Able to perform spirometry
• Having a smartphone
• Written consent adapted to the age
• Affiliated with a social insurance

Exclusion Criteria:

• Antibiotic therapy for a pulmonary exacerbation in the 2 weeks before enrollment
• Lung transplantation (past or future)
• Colonization with Bulkholderia cepacia in the last 2 years
• Absence of contentment
• Inability to access technology required to transmit home spirometry data
• Inability to speak and read French well enough to understand the use of the home spirometry and to complete the questionaries