Methods and apparatus for determining cuff blood pressure

• US 10,136,823 B2
• Filed: 08/28/2013
• Issued: 11/27/2018
• Est. Priority Date: 08/28/2012
• Status: Active Grant

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Mukkamala, Ramakrishna, Liu, Jiankun, Hahn, Jin-Oh
• Primary Examiner(s): Agahi, Puya
• Application Number:
  US14/012,124
• Publication Number:
  US 20140066793A1
• Time in Patent Office: 1,917 Days
• CPC Class Codes: A61B 5/02 Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
• CPC Class Codes: A61B 5/02208 using the Korotkoff method
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence

Abstract

A method is provided for determining blood pressure for a subject using a sphygmomanometer. The method includes: measuring an oscillometric cuff pressure waveform of the subject using the sphygmomanometer; representing the measured waveform with a physical model accounting for mechanics of the cuff, an artery and coupling between the cuff and the artery; determining the model unknowns from the measured waveform; and determining blood pressure for the subject using the determined model.

Claims

1. A method for determining blood pressure for a subject using a sphygmomanometer having a cuff and a pressure sensor integrated therein, comprising:

measuring an oscillometric cuff pressure waveform of the subject using the sphygmomanometer, where the oscillometric cuff pressure waveform indicates the time evolution of the pressure inside the cuff during inflation and deflation of the cuff;

measuring volume of air pumped into and out of the cuff during inflation and deflation of the cuff;

determining the cross-sectional area waveform of the artery underneath the cuff using the volume of air pumped into and out of the cuff and the measured oscillometric cuff pressure waveform;

determining an envelope of the cross-sectional area waveform as a function of the measured oscillometric cuff pressure waveform; and

determining, by the computer processor, blood pressure for the subject using the envelope.

3. The method of claim 1 wherein determining the cross-sectional area waveform of the artery further comprises determining an absolute cross-sectional area waveform using known parameters for the cuff of the sphygmomanometer, the volume of air pumped into and out of the cuff physical model and the measured oscillometric cuff pressure waveform.

4. The method of claim 1 wherein determining blood pressure for the subject using the envelope further comprises representing the envelope with a physical model with unknown parameters and fitting the physical model to the envelope to estimate the parameters, where blood pressure is one of the estimated parameters of the physical model.

5. The method of claim 1 wherein determining blood pressure for the subject using the envelope further comprises horizontally shifting the envelope to yield an arterial area-pressure relationship, applying the cross-sectional area waveform to the arterial area-pressure relationship to yield transmural pressure, and then adding cuff pressure to the transmural pressure to yield blood pressure.

2. A method for determining blood pressure for a subject using an oscillometric cuff device, comprising:

measuring cuff pressure using an oscillometric cuff device by inflating and deflating a cuff placed over an artery of the subject;

deriving an oscillogram from the measured cuff pressure, where the oscillogram is an amplitude of oscillations in the measured cuff pressure as a function of the measured cuff pressure;

determining an envelope difference between an upper envelope of the oscillogram and a lower envelope of the oscillogram;

representing the envelope difference as a difference in a parametric model, where the parametric model is defined in terms of parameters with unknown values and specifies a nonlinear area-pressure relationship of the artery underneath a cuff of the oscillometric cuff device at systole and diastole;

estimating values for all of the parameters of the parametric model simultaneously by fitting the parametric model to the envelope difference including amplitude of the envelope difference; and

determining blood pressure from the subject from the values of the parameters of the parametric model.

6. A method for determining blood pressure for a subject using an oscillometric cuff device, comprising:

measuring cuff pressure using an oscillometric cuff device by inflating and deflating a cuff placed over an artery of the subject;

deriving an oscillogram from the measured cuff pressure, where the oscillogram is an amplitude of oscillations in the measured cuff pressure as a function of the measured cuff pressure;

determining an envelope difference between an upper envelope of the oscillogram and a lower envelope of the oscillogram;

representing the envelope difference as a difference in a parametric model, where the parametric model is defined in terms of parameters with unknown values and specifies a nonlinear area-pressure relationship of the artery underneath a cuff of the oscillometric cuff device at systole and diastole;

estimating values for the parameters of the parametric model by fitting the parametric model to a portion of the envelope difference; and

determining blood pressure from the subject from the values of the parameters of the parametric model.