Temperature Optimization in Afebrile Septic PatienTs

The goal of this interventional study is to learn if external warming works to treat patients with a serious systemic infection (i.e. sepsis) that do not have fever. These patients have a higher risk of dying than patients with fever. It is possible that these patients might benefit from artificial external warming with the means to increase body temperature. It is unknown what the mechanism is, but it might be related to the immune system and how the body manages blood pressure and perfusion. The main questions to answer are: * Does external warming of the body influence certain inflammatory proteins in the blood? * Does external warming of the body influence prognosis and/or clinical condition? Researchers will compare external warming to standard clinical practice to see if external warming works to treat sepsis without fever. Participants will: \- receive treatment with external warming or treatment according to clinical practice