Non-invasive ambulatory blood pressure monitoring: technical possibilities and problems

Non-invasive automatic 24-h indirect ambulatory monitoring of blood pressure and the heart rate was performed in 2010 subjects at the Department of Internal Medicine, Klinikum Steglitz, Free University of Berlin, Germany, from 1983 to 1990. Blood pressure profiles were obtained using seven different monitors, Pressurometer III (Del Mar Avionics), Physioport (Natic), Accutracker (Oxford), Blutdrucksystem (Medizintechnik), SL 5200, SL 90202 and SL 90207 (SpaceLabs). The monitors were equipped with auscultatory and/or oscillometric devices, provided accurate readings and were repeatedly used up to eight times in some patients. Up to 100 data points per 24 h provided diurnal blood pressure profiles for over 91% of the patients in clinical and non-clinical situations. Early identification of borderline hypertensives at risk of cardiovascular disease and detailed information on the efficacy of different antihypertensive regimens may in part justify the high costs of the monitors. Although disturbance to sleep remained a problem in more than 20% of the patients investigated, the new, lighter, quieter monitors (e.g. SpaceLabs 90207 at 380 g) were well received by patients and nurses. In the future, simultaneous registration with 24-h ECG may help in identifying the effects of different antihypertensive therapies on blood pressure variability and the periodicity of the heart rate.