VARIABILITY: THE HALLMARK OF BLOOD PRESSURE MEASUREMENT - TYPES, ASSESSMENT AND PROGNOSTIC SIGNIFICANCE

Systemic blood pressure, recorded by various parameters, always shows variation. This is known as ' variability ', an entity not assessed routinely. Research has shown greater prognostic importance of it than routine parameters. Various intrinsic and extrinsic factors modulate it. Depending on the interval of successive readings, blood pressure variability is of five types, with different non-invasive methods utilized for recording. It is calculated by various statistical parameters, the most common being standard deviation, but average real variability is the most accurate and easily applied. Clinical evidence is increasing rapidly, indicating variability as a prognostic marker for stroke, ischemic heart disease, renal failure, cognitive dysfunction, heart failure, and mortality. Therapeutic measures for the control of variability have also been forwarded. The paucity of clinical application of blood pressure variability is the stimulus to narrate this review, especially for physicians managing hypertensive patients.