[The usefulness and limits of the ambulatory monitoring of arterial pressure].

The interpretation of blood pressure values, measured by the physician in the medical environment, has some limitations. Blood pressure fluctuates considerably due to circadian rhythm and various environmental stimuli and thus casual readings may not be representative of the true blood pressure status of the patient. Non-invasive ambulatory blood pressure monitoring has greatly increased our knowledge regarding the diagnosis, treatment efficacy, natural history and even prognosis of hypertension. This technique allows the evaluation of repeated blood pressure measurements at given times (daytime, nighttime, early-morning) and in different conditions (awake, asleep, at rest, during physical or mental activity etc.). Many studies have shown that the whole-day values obtained with such devices correlate better with the morbidity and mortality associated with hypertension than does casual office blood pressure. The 24-hour blood pressure recording is useful in the diagnosis of hypertension, particularly to discriminate so called white coat hypertension (for which the term isolated clinic hypertension has recently been proposed). Ambulatory blood pressure monitoring provides reliable and detailed information on the efficacy of pharmacological treatment and its ability to cover the whole day. These considerations notwithstanding, the application of this technique is still far from routine in the clinical management of arterial hypertension. Its major limit is that the normalcy of ambulatory blood pressure values still remains to be calculated, and only hypothetical normal reference values, derived from studies of selected normotensive populations, are presently available.