Circulatory shock is defined as an imbalance between oxygen supply and/or impaired oxygen use to maintain organ function. With growing evidence of lack of correlation between macro- and micro-circulation, use of "Whole Body" markers such as blood pressure (BP) or Lactates are often insufficient to assess the severity of the oxygen debt and/or tissue hypoperfusion. Thus, an approach incorporating tissue-perfusion based endpoints would represent a significant step up to guide optimal resuscitation of critically-ill patients and to reduce complications in high-risk surgery.

Current monitoring techniques, that complement systemic hemodynamics by focusing on regional perfusion, still lack the required user-friendliness and/or clinical relevance to be routinely used at bedside. Therefore, assessment of the adequacy of tissue perfusion and oxygenation is suboptimal, and implementation of the above-mentioned approaches of resuscitation is still a challenge.

Urethral perfusion is likely to be early and significantly impaired during low-flow states and thus represents a good "candidate" as a surrogate site to assess the perfusion of visceral organs. Besides, urethral mucosa can be investigated in a less invasive and simpler manner than "deeper" organs. Nowadays, no practical methods or devices are available to monitor perfusion in the pelvic area. Thus, recent development of a new monitoring device of urethral perfusion could fill this need and enable enhanced management of patients in Intensive Care Units (ICU) and Operating Rooms (OR).

The device consists of a modified Foley catheter equipped with a photoplethysmographic sensor: the IKORUS UP probe.

The probe will be used by intensivists or anesthesiologists on high-risk surgical patients, i.e. patients with comorbidities undergoing major vascular, thoracic and/or abdominal surgery.

Inclusion criteria:

1. 18 years of age or more,
2. Male or female,
3. High-Risk surgical patient,
4. Life expectancy expected to exceed 72 hours,
5. Willing to participate and signed informed consent,
6. Affiliation to the French social security system.

Non inclusion criteria:

1. Pregnant or lactating woman,
2. History of recent urological surgery (bladder surgery, prostate surgery…),
3. Known stricture or "impossible insertion" last hospitalization,
4. Traumatic injury to the lower urinary tract,
5. History of radiotherapy of pelvic or genital area,
6. Genital malformation (Hypospadias…).