Blood pressure difference between the measurements taken during cuff inflation and deflation

There is little quantitative clinical data available to support blood pressure measurement accuracy during cuff inflation. This study aimed to provide these data. Manual auscultatory systolic and diastolic blood pressures (SBP and DBP) were obtained from 15 subjects during cuff inflation and deflation. During the measurement, the oscillometric cuff pressure was inflated and deflated linearly at the same rate of 2-3 mmHg/s, and was recorded digitally for off-line analysis. Automated mean arterial pressures (MAPs) were then determined from both cuff inflation and deflation, corresponding to the cuff pressures at the peak of the 6th order polynomial model envelope fitted to the sequence of oscillometric pulse amplitudes. The manual SBP, manual DBP and automated MAP measured during cuff inflation and deflation were finally compared. The manual SBP measured during cuff inflation was significantly lower by 4.3 mmHg (mean±SD: 110.6±9.7 vs 114.9±9.0) than that measured during cuff deflation (P<;0.001). However, the manual DBP from cuff inflation was significantly higher by 3.0 mmHg (76.7±7.8 vs 73.6±7.2) than that from cuff deflation (P<;0.01), and the automated MAP from cuff inflation was also significantly higher by 4.5 mmHg (88.3±7.4 vs 83.9±8.7) (P<;0.01). In conclusion, this study quantitatively showed that blood pressures measured during cuff inflation and deflation were different.