Delirium is a common complication following hip fracture surgery (HFS) in older people. Postoperative hypoxia has also been associated with delirium, but not specifically in geriatric patients. The aim of the study is to demonstrate that post-operative hypoxia is associated with in-hospital complications in patients with HFS.

Patients hospitalized in orthogeriatric unit after HFS will be monitored for nocturnal SpO2 with a pulse oximeter continuously during 3 nights. In-hospital complications will be recorded prospectively in all patients, especially the occurrence of delirium with the CAM scale. The hypoxia vs non-hypoxia (more than 20% of the time spent with SpO2<90%) groups will be analyzed for clinical characteristics, comorbidities and medication use.

The statistical association between severe post-operative nocturnal hypoxemia and occurrence of delirium will be assessed. The dependance between this association and daytime SpO2 will also be assessed. The potential confirmation of an association between post-operative nocturnal hypoxemia in patients with HFS and the occurrence of delirium will lead the reflection on a clinical trial testing the benefit of oxygen therapy in the prevention of post-operative delirium, to improve the medical care of orthogeriatric patients.

Inclusion Criteria:

• age over 70 years old,
• hospitalized in orthogeriatrics for hip fracture surgery
• information about the study and expression of non opposition
• Expected hospital stay of 5 nights or more

Exclusion Criteria:

• patient under guardianship,
• any other type of fracture associated,
• oxymetry recording not possible (behavioral disorders, night stirring,...)