Indirect continuous blood pressure method

• US 5,111,826 A
• Filed: 03/16/1987
• Issued: 05/12/1992
• Est. Priority Date: 12/07/1984
• Status: Expired due to Fees

• Current Assignee: Roger E. Nasiff
• Original Assignee: Roger E. Nasiff
• Inventors: Nasiff, Roger E.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): SHAY, DAVID M
• Application Number:
  US07/026,434
• Time in Patent Office: 1,884 Days
• Field of Search: 128/672, 128/677, 128/679-691
• US Class Current: 600/485
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/025 within occluders, e.g. responsive to Korotkoff sounds electric stethoscopes A61B7/04

Abstract

A piezoelectric transducer clamped onto the fingertip with a fixed pressure yields an indirect continuous blood pressure waveform that can be used to monitor a patient'"'"'s blood pressure characteristics over extended periods of time and during most normal daily activities. There are two modes that this invention can operate in: absolute and relative pressure modes. In the absolute mode, a patient-calibrated clamping pressure is applied to hold the transducer in place and to cancel artifact. The systolic and diastolic blood pressure are taken directly from the measured waveforms. The systolic pressure equals the maximum peak pressure minus the clamping pressure. The diastolic pressure equals the minimum pressure minus the clamping pressure. In the relative mode, if patient motion artifact is not expected to be a problem, a patient-calibrated clamping pressure is not needed, because only a clamping pressure high enough to hold the transducer in place and low enough so as not to cause waveform distortion is needed. Since only relative pressures are measured with this mode the initially known systolic and diastolic pressures are used to calibrate the apparatus for subsequent pressure readings. The measured waveform systolic pressure and the measured diastolic waveform pressure corresponds to the initially known diastolic pressure.

Claims

1. The method of determining the absolute blood pressure comprising the steps of:

applying a piezoelectric pressure transducer having an output signal indicating a total pressure onto a palmar side of the 3rd finger segment of a hand,

clamping said transducer onto said finger with a fluid-filled cuff,

attaching an ultrasonic hand position/height sensor which produces a pressure signal to the hand and heart levels,

converting the output signal from said transducer to a voltage signal for use as a direct indicator of blood pressure,

measuring said voltage signal that indicates the total pressure on said piezoelectric transducer,

measuring pressure in the cuff in terms of a voltage that indicates the said cuff pressure, and

defining the blood pressure, in terms of a voltage, as said piezoelectric pressure indicating voltage minus said cuff pressure indicating voltage minus said ultrasonic hand position/height sensor pressure signal.

2. The method determining the relative blood pressure comprising the steps of:

applying a piezoelectric pressure transducer having an output signal indicating a total pressure onto a palmar side of the 3rd finger segment of a hand,

clamping said transducer onto said finger with a fluid filled cuff,

attaching an ultrasonic hand position/height sensor which produces a pressure signal to the hand and heart levels,

converting the output signal from said transducer to a voltage signal for use as a direct indicator of blood pressure,

measuring said voltage signal (Vo) that indicates total pressure on said piezoelectric transducer, noting that the total pressure is the a of blood pressure, clamping pressure and artifact pressure,

measuring the cuff pressure in terms of a voltage that indicates said cuff pressure, noting that the cuff pressure is a sum of the clamping pressure and the artifact pressure,

defining blood pressure indicating voltage as said piezoelectric indicating voltage minus said cuff pressure indicating voltage,

defining measured systolic voltage (msv) as a maximum voltage point on said voltage signal,

defining measured diastolic voltage (mdv) as a minimum voltage point on said voltage signal,

measuring a patient'"'"'s systolic (sysp) and diastolic (diasp) pressures using an industry standard method, and

defining blood pressure from a relationship of measured data, such as;

##EQU1##

3. The method of determining the absolute blood pressure comprising the steps of:

applying a piezoelectric pressure transducer having an output signal indicating a total pressure onto a palmar side of the 3rd finger segment of a hand,

clamping said transducer onto said finger with a fluid filled cuff,

attaching a joint position sensor which produce a pressure signal to elbow and shoulder joints,

converting the output signal from said transducer to a voltage signal for use as a direct indicator of blood pressure,

measuring said voltage signal that indicates the total pressure on said piezoelectric transducer,

measuring pressure in the cuff in terms of a voltage that indicates the said cuff pressure, and

defining the blood pressure, in terms of a voltage, as said piezoelectric pressure indicating voltage minus said cuff pressure indicating voltage minus said joint position sensors pressure signal.

4. The method of claim 3,

wherein the step of attaching includes the steps of attaching a joint sensor to a wrist.

5. The method determining the relative blood pressure comprising the steps of:

applying a piezoelectric pressure transducer having an output signal indicating a total pressure onto a palmar side of the 3rd finger segment of a hand,

clamping said transducer onto said finger with a fluid filled cuff,

attaching a joint position sensor which produces a pressure signal to elbow and shoulder joints,

converting the output signal from said transducer to a voltage signal for use as a direct indicator of blood pressure,

measuring said voltage signal (Vo) that indicates total pressure on said piezoelectric transducer, noting that the total pressure is a sum of blood pressure, clamping pressure and artifact pressure,

measuring the cuff pressure in terms of a voltage that indicates said cuff pressure, noting that the cuff pressure is a sum of the clamping pressure and the artifact pressure,

defining blood pressure indicating voltage as said piezoelectric indicating voltage minus said cuff pressure indicating voltage,

defining measured systolic voltage (msv) as a maximum voltage point on said voltage signal,

defining measured diastolic voltage (mdv) as a minimum voltage point on said voltage signal,

measuring a patient'"'"'s systolic (sysp) and diastolic (diasp) pressures using an industry standard method, and

defining blood pressure from a relationship of measured data, such as;

##EQU2##

6. The method of claim 5,

wherein the step of attaching includes the step of attaching a joint sensor to a wrist.