Effect of Sphygmomanometric Inflatable Cuff Properties on Blood Pressure Measurement

  • Shenela Naqvi

Student thesis: Phd

Abstract

The principal component of any non-invasive blood pressure (BP) measurement system is the inflatable cuff. A wide range of cuffs with different geometrical and mechanical properties are used all over the world every day. Variation in the cuff types may result in non-standard pressure distribution on the arm and on to the artery. To investigate pressure distribution under different types of BP cuffs, a simple model of arm using foam was developed. Pressure measured at the interfaces was found to be non-uniform, and the pressure distribution was different for different cuff type. Numerical simulation of experimental cuff assemblies were carried out using ABAQUS, and both sets of results were compared. The simple arm model was modified by replacing foam with vulcanized silicion rubber which possesses mechanical properties closer to human arm. This model also included a rubber tube simulating the brachial artery. Thirty-seven cuffs were used in the experiment. Both inside-cuff pressure and interface pressures were measured. The pressure over the artery was estimated from numerical simulation. Variations in the arterial pressure under different BP cuffs were found to be 28 mmHg and 15 mmHg for systolic and diastolic blood pressure respectively. Pressure transmission ratio from BP cuff to arterial wall was less than 80%. The effect of different types of inflatable cuffs on the arterial pressure in the human upper limb was investigated in detail by creating another numerical model using Dicom data obtained from MRI scan of a human upper arm. The model arm was loaded with experimentally obtained interface pressure for eight different types of cuffs. Variations in systolic and diastolic blood pressures were in a range of 27 mmHg and 17 mmHg respectively. Pressure transmission from the arm to the arterial surface was less than 90% under all the BP cuffs except the one with rubber bladder which showed 95% transmission ratio.Wide variations in the inside-cuff pressure, interface pressure and arterial pressure values were found within the cuffs of same type, among the cuffs of different types and among similar cuffs supplied by one manufacturer. The variations found in the pressure distribution could lead to inaccurate representations of subject's true blood pressure. The current research clearly indicates the need for development of a new type of BP cuff. The designing of the cuff would benefit from the knowledge generated within this research. It is crucial that a BP cuff applies a recognized pattern of pressure around the arm. The pressure on arterial wall should be either the same or a known fraction of the pressure inside the cuff.
Date of Award1 Aug 2013
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorVenkata Potluri (Supervisor)

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