FEM simulation and experimental evaluation of the `squeezing´ phenomenon in Riva-Rocci blood pressure measurement

The authors measured arterial pressure repeatedly in some patients by means of an automatic procedure based on the Riva-Rocci method, under the control of a personal computer. These measurements demonstrated that frequently repeated cuff inflation manoeuvres can cause a significant decrease in the estimated diastolic and systolic pressure values, which, in certain patients, are as great as 10 mmHg. This phenomenon may be ascribed to alterations in arm tissue elastic parameters. In order to test this hypothesis, the authors developed a finite element model of pressure transmission across the soft tissue of the arm. Computer simulations show that pressure distribution across the arm is significantly affected by the values of elastic parameters, especially by a decrease in Poisson ratio. Alterations in elastic parameters may be relevant not only when performing repeated squeezing manoeuvres, but also when arterial pressure is estimated in particular pathological subjects (such as obese or old-aged patients)