A new double cuff sphygmotonometer for accurate blood pressure measurement

Accurate measurement of blood pressure (BP) is essential in the diagnosis a nd treatment of hypertension, but neither auscultatory nor oscillometric me thods measure intra-arterial BP accurately in all circumstances. Algorithms for automatic BP-measuring devices differ from manufacturer to manufacture r, and no clear authorized algorithm criteria have yet been established. We have devised a double-cuff sphygmotonometer to measure BP on the basis of clear algorithms, and investigated the accuracy of this new method by compa ring it with the photo-oscillometric method, which is the most accurate met hod for non-invasive measurement of intra-arterial BP. In the new method, a small cuff (3x6 cm) replaces the photo-sensor in the brachial cuff (13x24 cm) of the photo-oscillometric device, and BP is determined by means of the oscillation within the small cuff. The comparison based on procedures of A AMI-protocol was performed in 136 hypertensive patients and 54 normotensive subjects. The difference in systolic BP between the photo-oscillometric an d double-cuff methods was -2.26+/-2.31 mmHg (89% under 5 mmHg), and the cor responding difference in diastolic BP was 1.9+/-2.50 mmHg (94% under 5 mmHg ). In conclusion, we have devised a new double-cuff method which improves o n the photo-oscillometric method, and although it seems to be less accurate than the photo-oscillometric method, the clarity of its algorithm makes it superior to the conventional oscillometric and auscultatory methods employ ing only one cuff.