A popular validated home monitor uses the maximum oscillogram amplitude to compute blood pressure

Oscillometric cuff devices are believed to use fixed ratio algorithms to compute blood pressure (BP) from the oscillogram (cuff pressure oscillation height versus applied cuff pressure function). However, variations in the cuff transducer that occur each time the cuff is wrapped on a given arm and variations in pulse pressure can alter the oscillogram shape and the ratios for computing BP. A popular validated home BP monitor was studied to determine whether and how it considers these effects. The monitor, with its Universal cuff placed on four different mandrels, was analyzed using a non-invasive BP simulator at various settings and an external pressure sensor to construct the oscillograms. Several algorithms were tested to estimate the home monitor BP values. A fixed ratio algorithm estimated the home monitor systolic and diastolic BP with errors of 5.8 and 1.5 mmHg. A variable ratio algorithm in which the ratios go inversely with the maximum oscillogram amplitude estimated the home monitor values with errors of just 1.5 and 0.8 mmHg. Using the maximum oscillogram amplitude may be particularly helpful for mitigating the variable pulse pressure effect. This study shows how oscillometric cuff devices likely work, which is important for understanding and improving their accuracy.