Healthy volunteers part:  Inclusion Criteria:  healthy volunteer without upper limb arterial disease absence of opposition affiliated to social insurance  Exclusion Criteria:  under 18 yrs old under law protection pregnancy  Retrospective patients part:  Inclusion Criteria:  patients with a TCPO2 measurement available for the upper limb patients with a follow-up of at least 3 months available absence of opposition affiliated to social insurance  Exclusion Criteria:  under 18 yrs old under law protection pregnancy