Peripheral blood pressure measurement is as good as applanation tonometry at predicting ascending aortic blood pressure

Abstract

The transfer function in the Sphygmocor system significantly underestimated invasively measured systolic blood pressure [mean -7.23 +/- 10.07 mmHg; 95% confidence interval (CI) -3.3 to -11.14 mmHg, P = 0.001] and significantly overestimated invasively measured diastolic blood pressure (mean 12.20 +/- 7.14 mmHg; 95% CI 9.43 to 14.97 mmHg, P <0.001). Oscillometrically measured brachial systolic blood pressure was not significantly different from that measured invasively in the ascending aorta (mean 3.36 +/- 10.47 mmHg; 95% CI -0.69 to 7.43 mmHg, P = 0.1), but oscillometric measurement of brachial diastolic blood pressure gave a significant overestimation of that measured invasively (mean 11.70 +/- 7.18 mmHg; 95% CI 8.91 to 14.49 mmHg, P <0.001). CONCLUSIONS The transfer function in the Sphygmocor system is no better at estimating ascending aortic blood pressure than are standard peripheral blood pressure measurements. It may be necessary to derive a new transfer system that is based on data that are acquired entirely non-invasively.