In this prospective observational study among sickle cell children aged 7 to 17 years, who face many experience of pain, pain will be assessed during incentive spirometry sessions. Then a relation between, inspiratory volume, pain and the length of hospital stay will be identified .

Currently, there is no scientific data regarding the correlation between acute pain during vaso-occlusive crisis, incentive spirometry and the impact on length of hospital stay. In fact, physiotherapist experience's in the pediatric department suggests that the pain expressed by the child is not always correlated with inspiratory capacity.

The absence of pain is one of the reasons for hospital discharge after decompensation in patients with sickle cell disease. However, no scientific study has linked incentive spirometry, pain and length of hospital stay.

Investigator assume that these children underestimate the real pain and its impact on breathing pattern, and presume that the maximal inspiratory volume during spirometry sessions will be a better reflect of pain than standard pain scale.

The aim of this study is to show that inspiratory volume would be a better indicator of discharge from hospitalization than actual pain scales.

Inclusion Criteria:

• Sickle cell children aged 7 to 17 admitted to the pediatric ward
• Children receiving respiratory physiotherapy sessions under medical prescription
• Children hospitalized for more than 24 hours at the CHRO and benefiting from more than one physiotherapy session.
• Absence of opposition of one of the parents to the participation of their child in the study
• Absence of opposition of children able to understand the study

Non inclusion Criteria:

• Sickle cell children under the age of 7 or over 17
• Children with mental deficits
• Non-French-speaking parents
• Children receiving only one physiotherapy session and being hospitalized within 24 hours

sickle cell children admitted to the paediatric department at the CHR of Orléans