Automated blood pressure monitoring for the assessment of antihypertensive treatment.

Whole-day automated monitoring with small portable devices allows the circadian pattern of blood pressure to be assessed conveniently in individual patients. Measurements provided by this technique appear to be more reproducible and physiologically relevant than conventional office readings. Ambulatory monitoring can enhance the evaluation of antihypertensive therapy, especially in clinical trials, in 3 ways. First, it can facilitate the diagnosis of hypertension and avoid potentially inappropriate treatment in patients whose hypertension is erroneously diagnosed by office measurements. Moreover, the monitoring technique appears to prevent placebo responses in therapeutic studies. Second, whole-day monitoring allows clear quantification of treatment effects. Because the standard deviations of treatment-induced blood pressure differences are lower with this method than with conventional readings, valid statistical evaluation of antihypertensive effects can be performed with far fewer patients. Finally, duration of action of drugs can be measured. By dividing the day into sequential periods (typically 12 two-hour periods), it is possible to determine statistical differences between baseline and treatment blood pressure values throughout the dosing intervals of the drugs being tested. This method may be more sensitive than the traditional "peak and trough" approach for assessing duration of action; it is not influenced by unsuspected discrepancies between the pharmacokinetic and pharmacodynamic properties of drugs, and can also provide information on nighttime effects. Thus, automated whole-day blood pressure monitoring appears to be a powerful tool for the evaluation of antihypertensive therapy.