To describe the expected spectrum of microcirculatory impairment during different stages of sepsis, septic shock and comparable critical disease, firstly US registrations are needed from persons with known normal microcirculation. Then, registrations of normal microcirculation are needed in persons exposed to increasing amounts of circulatory stress. Finally, microcirculatory conditions will be observed in patients with critical septic shock. Thus, firstly healthy volunteers are included, then stabile patients undergoing major planned surgery, and finally patients in critical septic shock demanding advanced intensive care treatment and monitoring.