A new portable device for recording 24-h indirect blood pressure in hypertensive outpatients

To simplify 24-h blood pressure (BP) recording in hypertensive outpatients, we devised a new portable, automatic BP recorder and studied its accuracy and usefulness. The fully automatic recorder, measuring 5 x 16 x 18 cm with a cuff of usual size, weighs approximately 1 kg and is driven by a rechargeable battery. The cuff is inflated by a compact CO2 cartridge and two microphones are used to detect differentially the Korotkoff sounds in the upper arm. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) are automatically measured, displayed with the time of measurement, and recorded on a memory card at intervals of 15 min for 24 h. This equipment has high noise immunity and works very quietly. It predicts approximate BP during the period of increasing cuff pressure, and measures BP more quickly than the conventional method (the time required for each measurement was reduced by about half). Afterwards, mean values with standard deviations, trendgrams and histograms of BP and HR over a certain period of time can be displayed and recorded with an accessory analyser. The accuracy of the BP values recorded by this device were compared with those measured by the auscultatory method. The average differences were -0.6 +/- 2.1 (s.d.) mmHg for SBP and 0.2 +/- 3.0 mmHg for DBP (n = 152). The BP values by this method were also compared with those obtained directly from the brachial artery, the differences being -5.8 +/- 5.9/0.3 +/- 6.0 mmHg (n = 85). In 30 ambulatory hypertensive patients, 24-h BP was recorded using this recorder.(ABSTRACT TRUNCATED AT 250 WORDS)