Method of measuring blood pressure with a plethysmograph
First Claim
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1. A method of determining arterial blood pressures, comprising:
- attaching a plethysmograph to a patient so that said plethysmograph interacts with an artery of said patient, said plethysmograph generating an output signal having a predetermined relationship to a characteristic of blood in said artery;
calibrating said plethysmograph during a calibration period by determining the patient'"'"'s actual arterial blood pressure by means other than said plethysmograph, and then determining the value of a first arterial characteristic in a predetermined relationship between said first arterial characteristic, arterial blood volume as indicated by said plethysmograph output signal, a conversion value corresponding to arterial blood volume at infinite pressure, and said actual arterial blood pressure during said calibration period; and
analyzing said plethysmograph output signal during a measurement period to determine an arterial blood pressure corresponding to said output signal in accordance with said predetermined relationship.
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Abstract
A method and apparatus for determining arterial blood pressures using a photoplethysmograph is provided. In the inventive method the photoplethysmograph output is calibrated to the patient using an auxiliary blood pressure determining instrument, a constant k particular to the patient'"'"'s arterial blood pressure-volume relationship is determined and is stored for later use; at the time of measurement information is obtained from the photoplethysmograph output; and a computer determines the patient'"'"'s systolic and diastolic blood pressures.
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Citations
13 Claims
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1. A method of determining arterial blood pressures, comprising:
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attaching a plethysmograph to a patient so that said plethysmograph interacts with an artery of said patient, said plethysmograph generating an output signal having a predetermined relationship to a characteristic of blood in said artery; calibrating said plethysmograph during a calibration period by determining the patient'"'"'s actual arterial blood pressure by means other than said plethysmograph, and then determining the value of a first arterial characteristic in a predetermined relationship between said first arterial characteristic, arterial blood volume as indicated by said plethysmograph output signal, a conversion value corresponding to arterial blood volume at infinite pressure, and said actual arterial blood pressure during said calibration period; and analyzing said plethysmograph output signal during a measurement period to determine an arterial blood pressure corresponding to said output signal in accordance with said predetermined relationship. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification