Abstract
Description The term "vital sign" has been attached to at least 83 conditions, symptoms, or phenomena in the literature to highlight their role and importance in overall health and well-being. This has created considerable confusion and overlapping terms in the medical literature. The 4 time-honored vital signs include temperature, pulse, blood pressure, and respiration. Two other measurements, blood oxygen saturation, and capnography (end-tidal CO2) are considered the fifth and sixth vital signs, respectively. The authors argue that exercise should be named a vital sign, and several authors have designated it as the fifth vital sign. However, not all symptoms or phenomena, such as exercise, are essential for life. This article traces the origins of the term "vital sign," reports on the various conditions named the fifth through eighth vital signs, and proposes an objective definition that describes the requirements for designating something as a vital sign.