[Tests and criteria in diagnosis of chronic hypotension--a systematic review]

The diagnosis of hypotensive circulatory disorders is based on a variety of criteria and classifications. This paper aims to provide a systematic review of published definitions and diagnostic criteria for hypotensive disorders. Searches for relevant papers were undertaken in Medline, Winspirs version (January 1966 to December 1999) and in textbooks of internal medicine. References of all identified articles were also searched. Publications in English, French, German and Italian were included. In 47 articles, 56 different reference were made to definitions and diagnostic criteria for hypotension. At present there is no uniform definition of hypotension and there are no clear, standardized criteria on which to base a diagnosis. Basically, one distinguishes between two schools of thought. The Anglo-American literature describes hypotensive disorders in terms of orthostatic dysregulation in the presence of an underlying primary condition, whereas the German-speaking countries use mixed approaches. On the one hand, the questionable pathological value of essential/primary hypotension is discussed; on the other hand, tests for orthostatic circulatory function, like the Schellong test, appear to have become established. Neither resting blood pressure limits nor a drop in blood pressure during orthostatic challenge can be used to diagnose hypotension. The orthostatic test is a better diagnostic tool than resting blood pressure. Hypotension is probably difficult to classify in simple terms because it is usually a symptom of numerous disorders hallmarked by a variety of pathophysiological mechanisms. Hypotension should indeed be understood as a secondary symptom of a primary disease. Accordingly, the primary aim of diagnostic efforts should be to uncover the underlying condition. The studies included were of insufficient methodological quality. Moreover, the heterogeneity among the individual studies made pooled analysis impossible. This systematic review revealed a marked lack of studies with valid results.