[Ambulatory 24-hour blood pressure monitoring. A comparative study of oscillometric and auscultatory blood pressure measurement].

The purpose of this study was to investigate the compatibility between oscillometric and auscultatory methods, and to determine whether one is preferable to the other for ambulatory 24 h blood pressure monitoring. We used an A & D TM 2421 blood pressure monitoring device. Our investigation included 281 patients with suspected hypertension or undergoing treatment for hypertension. We were able to compare 18,790 paired measurements. The difference (auscultatoric--oscillometric) in paired single readings between the two methods was 1.4 +/- 19 mmHg (mean +/- SD) for systolic and -2.4 +/- 18 mmHg for diastolic readings. The difference for 24 h monitoring amounted to 0.7 +/- 4 mmHg for systolic and -2.2 +/- 6 mmHg for diastolic measurements. The auscultatory method showed a uniformed distribution of errors throughout the 24 h, whereas the oscillometric method had fewer errors in the evenings, but more during working hours. A weak correlation between the difference and systolic blood pressure levels, age and pulse pressure was found. Difference in diastolic blood pressure correlated only weakly with the level of pulse pressure. Although we found a considerable SD on single readings, there was a good agreement between the mean values for the 24 h monitoring for the two methods. The findings suggest that, for this equipment, the oscillometric method is preferable for 24 h ambulatory blood pressure monitoring because it provides a much higher rate of successful readings.