The aim of the study is to determine the clinical value of using a powered alternating pressure air overlay mattress (P-APAM) in the prevention of pressure injury (PI) in patients at medium to high risk.

This study is noncomparative, observational study.

Patients older than 18 years of age, with a medium to high risk of PI, without PI, up during the day, and lying between 15 and 20 hours per day on a specific P-APAM will be included. The study will be conducted in nursing homes, and in long-stay geriatrics department.

Patients will be followed up for 35 days. The use of the P-APAM is associated with the usual PI prevention measures. The primary outcome is the percentage of patients who will develop at least one PI of at least stage 2 on the sacrum, spine, or heel between day 0 and day 35 . Secondary endpoints are patient assessments of comfort, caregiver satisfaction, mattress noise level, and mattress safety.

Inclusion Criteria:

• Patient over 18 years old
• Patient with a medium to high risk of developing pressure ulcers (clinical judgment and a score of [10 to 14] on the Braden scale (6 (maximum risk) to 23 (no risk))
• Patient without pressure injury on the day of inclusion
• Patient up during the day and lying down for more than 15 hours and less than 20 hours per day on an R'GO SOINS overlay mattress for less than 48 hours or since the day of inclusion
• Patient with a weight < 150kg
• Patient (or a trusted third party/legal representative) having been informed of the study and signing informed consent

Exclusion Criteria:

• Patient at end of life (estimated life expectancy less than 6 months)
• Patient discharge from the establishment expected within two months
• Patient already installed on an R'GO SOINS mattress topper for more than 48 hours before inclusion
• Patient with unstable spinal injury or other spinal disorder
• Patient with cervical or skeletal traction
• Patient with unstable spinal cord injury
• Patient with acute multiple trauma
• Patient with unstable posttraumatic bone fracture
• Participants will be excluded from the study if they meet the following combination of criteria indicative of malnutrition according to the 2021 French National Authority for Health guidelines (Participants must meet at least one phenotypic criterion and one etiological criterion to be considered malnourished and therefore ineligible for inclusion in the study) :

A) One or more of the following phenotypic criteria:

Significant unintentional weight loss: A weight loss of ≥ 5% within 1 month or ≥ 10% within 6 months Low Body Mass Index (BMI): BMI < 18.5 kg/m² for individuals under 70 years old, BMI < 21 kg/m² for individuals aged 70 years and older Reduced Muscle Mass Evident reduction in muscle mass AND

B) One of the following etiological criteria:

Inadequate nutritional intake:

Nutritional intake less than 50% of the energy requirements for more than one week Reduced food intake for more than two weeks Presence of Disease or Stress Metabolism Acute or chronic illness, or any condition causing metabolic stress that increases energy requirements

Patients in nursing homes or long-stay geriatrics department