Method and apparatus for compensating for transducer position in blood pressure monitoring system
First Claim
1. In a blood pressure monitoring system, an apparatus for compensating for the position of a pressure transducer relative to the position of a patient'"'"'s heart, comprising:
- means for sensing blood pressure in a blood vessel, said blood pressure comprising a first pressure component corresponding to the blood pressure in said patient'"'"'s heart and a second pressure component corresponding to the hydrostatic pressure of the blood contained in said blood vessel;
a pressure transducer having first and second pressure sensing ports, said transducer having means for comparing the relative magnitude of pressures sensed at said first and second ports and means for producing an output signal corresponding to the difference between the pressure sensed at said first and second ports;
means for creating an offsetting pressure equal to said second pressure component;
means for communicating said blood pressure sensed in said blood vessel to said first port of said pressure transducer; and
means for communicating said offsetting pressure to said second port of said pressure transducer.
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Accused Products
Abstract
A method and apparatus for ensuring accurate measurement of blood pressure regardless of the position of the sensing transducer relative to the position of the patient'"'"'s heart. The method and apparatus provides a hydrostatic balancing system in which a column of fluid is used to offset the hydrostatic pressure created by the corresponding column of blood contained in the blood vessel in the limb upon which the measurement is being taken. A flexible tube is routed along the patient'"'"'s limb with one end being positioned at heart level and the other end terminating at the occlusion cuff which supports the pressure sensing transducer. The tube is filled with fluid and is connected to a fluid reservoir chamber located at approximately the same level as the patient'"'"'s heart. The hydrostatic pressure created by the fluid in the tube effectively balances the corresponding hydrostatic pressure created by the blood in the blood vessel. At the cuff end of the tube, a differential pressure transducer senses the difference between the cuff pressure and that generated by the fluid column of the pressure compensation system. This signal, after appropriate scaling, can be used in conjunction with oscillometric signal processing software to provide an accurate representation of the patient'"'"'s actual blood pressure.
82 Citations
20 Claims
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1. In a blood pressure monitoring system, an apparatus for compensating for the position of a pressure transducer relative to the position of a patient'"'"'s heart, comprising:
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means for sensing blood pressure in a blood vessel, said blood pressure comprising a first pressure component corresponding to the blood pressure in said patient'"'"'s heart and a second pressure component corresponding to the hydrostatic pressure of the blood contained in said blood vessel; a pressure transducer having first and second pressure sensing ports, said transducer having means for comparing the relative magnitude of pressures sensed at said first and second ports and means for producing an output signal corresponding to the difference between the pressure sensed at said first and second ports; means for creating an offsetting pressure equal to said second pressure component; means for communicating said blood pressure sensed in said blood vessel to said first port of said pressure transducer; and means for communicating said offsetting pressure to said second port of said pressure transducer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for compensating for the position of a pressure transducer relative to the position of a patient'"'"'s heart, comprising:
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means for sensing blood pressure in a blood vessel, said blood pressure comprising a first pressure component corresponding to the pressure in said patient'"'"'s heart and a second pressure component corresponding to the hydrostatic pressure of the blood contained in said blood vessel; a differential pressure transducer having flrst and second pressure sensing ports, said transducer including means for comparing the relative magnitude of pressure sensed at said flrst and second ports and means for producing an output signal corresponding to the difference between the pressure sensed at said first and second ports; a flexible tube containing a column of fluid for creating an offsetting pressure equal to said second pressure component, said fluid having a density approximately equal to the density of blood; means for communicating said blood pressure sensed in said blood vessel to said flrst port of said differential pressure transducer; means for communicating said offsetting pressure to said second port of said differential pressure transducer; means for filtering transient pressure components from said offsetting pressure created by said fluid contained in said fluid-fllled tubbe; and means for absorbing pressure variations caused by temperature variations of said fluid contained in said fluid filled tube. - View Dependent Claims (14, 15, 16)
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17. In a blood pressure monitoring system, a method for compensating for the position of a pressure sensor relative to the position of a patient'"'"'s heart, comprising the steps of:
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measuring the blood pressure in a blood vessel, said blood pressure comprising a first pressure component corresponding to the pressure in said patient'"'"'s heart and a second pressure component corresponding to the hydrostatic pressure of the blood contained in the blood vessel; creating an offsetting pressure corresponding to said second pressure component subtracting said offsetting pressure component from said blood pressure measured in said blood vessel; and providing an output signal corresponding to the pressure in said patient'"'"'s heart. - View Dependent Claims (18, 19, 20)
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Specification