A comparison between the oscillometric and the auscultatory method for ambulatory 24 h blood pressure monitoring.
OBJECTIVES: To investigate the compatibility between oscillometric and auscultatory methods, and to determine whether one is preferable over the other for ambulatory 24 h blood pressure monitoring. METHODS: For the blood pressure monitoring system we used an A&D TM 2421 device (Takeda), which enabled us to measure the blood pressure simultaneously with the two methods on the same arm. Our investigation included 281 patients (122 women and 159 men, aged 18-85 years) with suspected hypertension or undergoing treatment for hypertension. RESULTS: We obtained 23 531 measurements by the oscillometric method, which was 98% of the maximal possible number, and 81% of the maximal possible number were obtained by the auscultatory methjod. We were able to compare 98% of the paired measurements. The auscultatory method showed a uniform distribution of errors throughout the 24 h. Compared to the auscultatory method, the oscillometry method had fewer errors in the evenings, but more when the subjects were at work. There was a difference in paired single readings between the two methods amounting to 1.4+/-19 mmHg (mean+/-SD) for systolic and -2.4+/-18 mmHg for diastolic readings (auscultatory - oscillometric). The differences in mean values for the 281 cases of 24 h monitoring amounted to 0.7+/- 4 mmHg for systolic and -2.2+/-6 mmHg for diastolic measurements. For the mean systolic blood pressure, we found a difference of 0.3+/-4 mmHg in the daytime and 0.3+/-8 mmHg during the night. The mean diastolic pressures differed by -2.0+/-6 mmHg in the daytime and -1.6+/-8 mmHg during the night. We found only a weak correlation between the differences in the readings by the two methods and systolic blood pressure levels, age, pulse pressure and body mass index, and no correlations between these differences and the diastolic blood pressure levels. CONCLUSION: Although we found a considerable SD on single readings by the two methods, there was a good agreement between the mean values of the 24 h monitoring for the two methods. We obtained a significantly higher success rate by the oscillometric method. 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.
Wiinberg
N
Frederiksberg Hospital, Department of Clinical Physiology, Frederiksberg, Denmark.
Raymond
IE
Bang
LE
Malmqvist
BB
Svendsen
TL
Petersen
LJ