With Covid period, inclusions can't be efficient.

Cardiac output (CO) is an essential physiological parameter of healthy person or illness.

In clinical practices, all methods of measuring the CO(Fick method, thoracic impedance, esophageal echodoppler etc) contain limit. Each method are dangerous or hard to implement.

CO is probably determining element of blood transit time and thus the availability of oxygen between the central organs (heart, lung) and the peripheral organs (leg, arms).

Our hypothesis is transcutaneous oxymetry mesurement with oxygen inhalation, to cause a transient hyperoxia, can be used to determinate blood transit time between central organs and peripheral organs. This simple method will be non invasive technique.

At admission eligible patients are proposed to participate. Written consent is signed after complete oral and written explanation of the protocol is signed.

The time of onset hyperoxia will be compare to usual CO method by cross correlation.

The duration of participation for subject is equal to 1 hour.

Inclusion Criteria:

• Adults over 18
• Cardiac output measurement considered at least 2 hours prior to the study
• Affiliation to a French National healthcare system
• Written informed consent must be obtained prior to protocol-specific

Exclusion Criteria:

• Acute or decompensated cardiac or respiratory failure
• Allergy to medical adhesives
• Patients under reinforced protection, pregnancy, deprived of liberty by judicial or administrative decision, hospitalized without consent or admitted to a health or social establishment for purposes other than research
• Inability to understand the instructions or objectives of the study