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US 5,140,990 AGranted
Method of measuring blood pressure with a photoplethysmograph
AssigneeSpaceLabs, Inc.
InventorsPaul H. Jones, Wei-Min Wang
Life of this patent
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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 pressure.
Claims11
A method of determining arterial blood pressures, comprising:
- attaching a photoplethysmograph sensor to a patient so that light from said sensor passes through an artery of said patient;
- connecting said sensor to a photoplethysmograph, said photoplethysmograph generating an electrical output signal having a predetermined relationship to the volume of blood in said artery;
- calibrating said photoplethysmograph during a calibration period by determining the patient's actual arterial blood pressure by means other than said photoplethysmograph, 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 photoplethysmograph output signal, a conversion constant corresponding to arterial blood volume at infinite pressure, and said actual arterial blood pressure during said calibration period;
- and
- analyzing said photoplethysmograph output signal during a measurement period to determine an arterial blood pressure corresponding to said output signal in accordance with said predetermined relationship.
2 more elements
Dependencies are inferred from the claim text.