24-hour blood pressure measurements: methodological and clinical problems

Awareness that sphygmomanometry is encompassed with serious limitations has led to the development of techniques that allow blood pressure (BP) to be monitored intraarterially or noninvasively during the day or over a 24-hour period. Although intraarterial BP monitoring allows an accurate evaluation of 24-hour BP mean and variability, its invasiveness prevents routine use in the clinical practice. This use can be more easily foreseen for noninvasive ambulatory BP monitoring, provided that the questions posed by this approach are answered. In the present study we show that the intermittent cuff inflations which allow BP to be measured noninvasively do not induce an alerting reaction and a BP rise in the patients, which means that this approach does not disrupt the daily BP profile. We also show that noninvasive BP monitoring does not alter the nocturnal hypotension, thus, preserving the day and night BP rhythm. Finally, we present evidence from a cross-sectional study that 24-hour BP monitoring reflects more closely the hypertension-related target organ damage than sphygmomanometric BP measurement and that target organ damage is related not only to average BP regimens but also to the degree of BP variability. Although support from prospective studies is necessary, this suggests that the diagnosis of hypertension and the prediction of its risk may be improved by ambulatory BP monitoring.