System and method of determining whether to recalibrate a blood pressure monitor

Abstract

A monitor for determining a patient's physiological parameter includes a calibration device that provides a calibration signal indicative of an accurate measurement of the patient's physiological parameter. The monitor also includes a processor, which receives a noninvasive signal from a noninvasive sensor positioned over a blood vessel. The processor uses the calibration signal to calibrate a relationship between the noninvasive signal and a property of the physiological parameter. The processor also determines when to recalibrate the relationship.

Description

RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application No. 10 / 052,977, filed on Jan. 17, 2002, which is a continuation of U.S. patent application No. 09 / 430,928, filed on Nov. 1, 1999 (the “Parent Application”), which is a continuation-in-part of U.S. patent application Ser. No. 09 / 026,048 filed Feb. 19, 1998, now U.S. Pat. No. 6,045,509, which is a continuation of U.S. patent application Ser. No. 08 / 556,547, filed No. 22, 1995, now U.S. Pat. No. 5,810,734, which claims priority benefit to U.S. Provisional Application No. 60 / 005,519, filed October 1995, wherein U.S. Pat. No. 5,810,734 is also a continuation-in-part of U.S. patent application Ser. No. 08 / 228,213, filed Apr. 15, 1994, now U.S. Pat. No. 5,590,649. The Parent Application and U.S. Pat. Nos. 6,045,509, 5,833,618, 5,830,131, and 5,590,649 are incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to an apparatus and method for noninvasively providing ...

AI Technical Summary

Benefits of technology

"The present invention describes an apparatus and method for measuring the induced perturbation of a patient's body tissue to determine the patient's blood pressure and other clinically important parameters. The invention allows for noninvasive and continuous measurement of blood pressure through a sensor attached to the patient. The sensor filters the noninvasive sensor signal to determine the induced component, which is related to the patient's blood pressure. The invention can also be used to analyze and track other physiological parameters such as vascular wall compliance, strength of ventricular contractions, vascular resistance, fluid volume, cardiac output, myocardial contractility and other related parameters."

Problems solved by technology

Prolonged reduction or loss of pressure severely limits the amount of tissue perfusion and could therefore result in damage to or even death of the tissue.

Often, these physiological factors and the given medications can result in a situation of rapidly changing blood pressure requiring immediate blood pressure measurement, and corrective action.

However, this technique is slow, subjective in nature, requires the intervention of a skilled clinician and does not provide timely readings frequently required in critical situations.

This is an inordinately long amount of time to wait for an updated pressure reading when fast acting medications are administered.

Also, too frequent cuff inflations over extended periods may result in ecchymosis and / or nerve damage in the area underlying the cuff.

The invasive method has inherent disadvantages including risk of embolization, infection, bleeding and vessel wall damage.

However, while these studies discuss the relationship between velocity and pressure they do not propose a practical method of measuring induced perturbations to determine blood pressure.

The phase difference of the sensor signals is displayed giving a signal that is capable of detecting changes in blood pressure, but which does not provide a calibrated blood pressure output.

Since it has been shown, for example by Landowne, that the relationship between pressure and signal propagation varies considerably from patient to patient, Salisbury's technique, based on a single formula, is not generally applicable.

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