The present invention pertains to a non-invasive way of assessing tissue perfusion in a patient, especially for treatment follow-up and prognosis of septic shock. More specifically, tissue perfusion is assessed by measuring the cutaneous partial pressure of carbon dioxide of said patient, for example at ear lobe with a PCO2 sensor which is not heated at a temperature superior to 37.5° C., and by calculating the difference between said cutaneous PCO2 and either the arterial or the end-tidal partial pressure of CO2. A device for performing a continuous non-invasive perfusion follow-up is also part of the invention.
