Does Increasing Oxygen Nurture Your Symptomatic Ischemic Ulcer Sufficiently?

Inclusion Criteria: 1. Type I or II diabetes 2. One or more deep and clinically infected lower extremity ulcers, classified as Meggitt-Wagner class 3 or 4, Texas class 2C, 3C, 2D or 3D, or WIfI class W\>1, I\>1 and fI\>0), present for at least 4 weeks or after a minor amputation because of a previously existing ischaemic DFU on a toe or forefoot. In case more than one ulcer is present, the largest will be observed as target ulcer 3. Leg ischaemia, characterized by a highest ankle systolic blood pressure \< 70 mmHg, or a toe systolic pressure \< 50 mmHg or a TcpO2 \< 40 mmHg 4. Complete assessment of peripheral arterial lesions from the aorta to the pedal arteries with duplex ultrasonography, magnetic resonance angiography, computed tomography angiography and/or intraarterial digital subtraction angiography of the ipsilateral leg 5. Patients have to be discussed in, and included after a multidisciplinary consultation. 6. Adults 7. Written informed consent Exclusion Criteria: 1. Chronic Obstructive Pulmonary Disease (COPD) GOLD IV 2. Treatment with chemotherapy, immunosuppressive drugs or systemic corticosteroids within last 3 months, as this interferes with normal wound healing 3. End-stage renal disease requiring dialysis 4. Metastasized malignancy 5. Left ventricular failure with ejection fraction (EF) \<20% or external pacemaker 6. Recent thoracic surgery or middle ear surgery 7. Severe epilepsy 8. Uncontrollable high fever 9. Pregnancy 10. Insufficient proficiency of local language/English, or inability to complete the questionnaires