Temperature is one of the vital signs usually monitored in patients of ICUs. Indeed, fever occurs frequently in ICU especially in brain injured patients and may require targeted temperature management (TTM) in special case as intracranial hypertension or post cardiac arrest. In ICU, non invasive device to monitor temperature are not recommended and only invasive ones are accurate enough for TTM. Arterial pulmonary temperature is still the gold standard, but esophageal device is currently used in ICU patients.