The aim of hemodynamic monitoring in intensive care is to recognize derangements in physiologic variables, which herald the progression toward organ failure. Traditionally the term "vital signs" refers to heart rate, arterial pressure, respiratory rate and body temperature monitoring. Continuous monitoring of vital signs, is advocated, since trends are more significant than single measurements, and is still a cornerstone, in the hemodynamic evaluation of a critically ill patient. Nevertheless, the spectrum of hemodynamic derangements that can arise during intensive care unit stay is very large and often additional information, beside the vital signs, are needed to evaluate correctly the individual patient.