JPH06285048A - Oxygen analyzer with perfusion enhancing means - Google Patents

Abstract

PURPOSE: To attempt easy and low-cost hematic perfusion in a detected location by applying substances which strengthen hematic perfusion to a specified location over a patient's skin, without use of iontophoresis, placing pulse oximeter- sensor in the specified location and measuring the oxygen saturation rate of the blood. CONSTITUTION: A small quantity of a surface stimulant 12 consisting of a mixture of methyl salicylate which is a known cream-base and menthol is applied to a specified detection location 10 of a patient's forehead. Next, an oximeter- sensor 14 is placed in the detection location 10 and pulse-oximeter measurement is performed it a normal way. Accordingly, the calculation of an oxygen level is performed by the pulse-oximeter monitor without correcting the baseline with a blood loss. Thus, a hematic perfusion at a detection location is performed easily and at a low cost.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to non-invasive measurement of blood characteristics of a patient, and more particularly to the use of a pulse oximeter to measure heart rate and oxygen saturation of the patient.

[0002]

2. Description of the Related Art The heart rate of a patient and the oxygen saturation of arterial blood are determined to be non-invasive.
It is well known to use a pulse oximeter to measure aswise). Generally, non-invasively measuring the oxygen saturation of arterial blood typically involves transcutaneous (partially transcutaneous).
Changes in the arterial blood volume in the tissue between blood pressure pulsations give rise to changes in the amount and characteristics of light detected by the sensor photoelectric detector. The pulse oximeter identifies arterial blood (rather than venous blood) from the pulsating components of the optical signal detected by the pulse oximeter sensor. The amount of light sent through the tissue at each wavelength may be compared to calculate how saturated the arterial blood flowing through the tissue is with oxygen. For details of the principles of the pulse oximeter, see US Pat.
498.

The quality of the pulse oximeter measurements is pulsatile in the concentration of arterial blood (relative to other tissue structures) in part of the tissue illuminated by the sensor and in part in the amount of blood in the tissue. Depends on the size of. For example, the finger is a preferred sensing location because relatively many blood vessels collect, but a highly perfused location, such as a finger, is not always available. In addition, blood flowing through the sensing location may be limited by ambient temperature, vasoconstricting drugs that act deliberately within the patient's bloodstream, or patient hypotension.

There is a recognized need in the prior art to increase the volume of arterial blood. A device called "Cyclops" is a medical reflection photometer, p. 50-77 (W. G. Gillestra, G.A. Mook) (Royal Vangorcum Ltd. Ass
en, 1962). The cyclops detects blood by measuring the amount of light reflected from the skin, and is preferably placed in the center of the forehead. From now on, it is named Cyclops. The skin is first treated with histamine phosphate. It is a counterirritant that has the effect of dilating blood vessels. As the blood vessels dilate, more blood flows, providing a larger signal to the sensor.

Histamine ion permeation method (iontophoresis)
A voltage is applied to the skin in order to put histamine phosphate in the tissue by the treatment referred to as. Subsequently, a pressure plate is applied to the skin so that the blood can be cleared and the baseline light reflection value can be measured. Blood can then flow into the dilated blood vessels and a blood oxygen level measurement is made.

The pulse oximeter device which has been developed in recent years is
Utilizes multiple light wavelengths and sophisticated waveform analysis. This waveform analysis eliminated the need to analyze blood at peaks and valleys of the waveform, thus eliminating blood and measuring the baseline. These devices have attempted to provide a simple, compact sensor that eliminates the multiple steps of conventional cyclops and applies the sensor once to do all the necessary preparation and analysis. For example, US Pat. No. 4,926,867 discloses a pulse oximeter sensor incorporating a heater and temperature control. This patent states that heating the sensing location on the patient's skin increases blood through the capillaries under the sensor and increases the pulse-to-pulse variation in the optical signal induced by the sensor. ing.

US Pat. No. 4,852,879 discloses another prior art approach to the blood perfusion problem. In this patent, the inventor acknowledges that adding a heater to the sensor complicates the construction and increases cost. Therefore, the inventor has added a thermally reflective metal layer to the pulse oximeter sensor to keep the body at the sensing location heated.

[0008]

SUMMARY OF THE INVENTION The present invention employs a surface stimulant that enriches the body parts with microvessels and uses a modern oximeter probe to apply simple pulse oxygen. Provided are a method and a device for performing total measurement. The surface stimulant is either applied to the skin just prior to placement of the probe, or is preferably included in an adhesive pad for bonding the probe to the skin.

The present invention is characterized in that a surface stimulant that enriches blood can be used without the necessity of the ion permeation method. Furthermore, the use of a unique adhesive pad allows the surface stimulant to be applied with the placement of the probe in a single step.

The present invention improves upon recent prior art systems. Since much of the heat in the tissue under the patient's skin is provided by the blood flowing through that tissue, primarily passive thermal sensor bandages may be useful when the ambient temperature is low. Such heat reflectors rarely improve the performance of the sensor when there is insufficient perfusion of blood due to other causes than the cold air surrounding the sensing location.

On the other hand, mechanical heaters are very complicated and costly. Furthermore, unregulated sensor heaters present a risk of burns. Therefore, there is a need for an easy and inexpensive way to enhance blood perfusion at the sensing location.

The method of the present invention meets this need. The invention is described in detail below with reference to the drawings.

[0013]

An example of the method of the present invention is shown in FIG.
As shown in FIG. 1 (a) and FIG. 1 (b), cream-based methyl salicilate
A small amount of a surface stimulant 12, such as a mixture of menthol and menthol (12% methyl salicylate, 9% menthol) is applied to a predetermined sensing location 10 on the patient's skin. This type of cream is sold in retail pharmacies under the trademark ICY HOT.

After application of the cream, an oximeter sensor 14 is placed at the sensing location and pulse oximeter measurements are made in the usual manner. In this example, the predetermined location 10 is the patient's forehead and the sensor 14 is a surface or transflectance pulse oximeter sensor such as a NELLCOR RS-10 sensor. Oxygen level calculations are made by the pulse oximeter monitor without the need to lose blood and correct the baseline. This is disclosed in US Pat. No. 4,521,643, which is incorporated herein by reference. Studies conducted have shown that application of a small amount of methyl salicylate cream to the sensing location of the patient's skin increases the magnitude of the optical pulses detected by the sensor.

Other locally acting blood perfusion enhancers (topical skin irritants and vasodilators), other methods of application,
It should be understood that other sensing locations, other sensor geometries can be used without departing from the scope of the invention. For example, a methyl salicylate cream may be applied to the patient's finger prior to placement of the transmissible finger pulse oximeter sensor.

As another example, the perfusion enhancer is ALZA
It can be applied to the sensing location via an adhesive patch, such as the motion sickness patch sold by the company. The use of an adhesive patch, such as a mass transfer device, results in a continuous application of the material over the detection period, which can extend the perfusion enhancing effect of the material. General guidelines for the construction and use of adhesive patches applied to the skin are described in US Pat.
687,481, 4,692,462, 4,764,
No. 382, No. 4,747,845, No. 3,993,073
It is shown in many things like issues. These disclosures are incorporated herein by reference. Sensor 14
One possible configuration of adhesive patch 22 including and a perfusion enhancing substance is shown in FIG. Holes 24 in the patch allow the sensor 14 to send and receive light.

Application of the substance may also be via the adhesive used to position the sensor at the sensing location on the patient. Other variations will be apparent to those of ordinary skill in the art.

[Brief description of drawings]

1 (a) to 1 (c) depict a method for optically measuring a blood characteristic of a patient according to one embodiment of the present invention.

FIG. 2 illustrates a patch and pulse oximeter sensor including a locally acting blood perfusion enhancer according to another embodiment of the invention.

[Explanation of symbols]

 10 Detection Location 12 Surface Stimulant 14 Sensor 22 Patch 24 Hole

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Paul D. Mannheimer, Reed Avenue 2619, Belmont, California, United States 2619 (72) Inventor Jessica A. Walling, Palm Avenue, Millbrae, California, United States 407

Claims (7)

[Claims] 1. A method for measuring the oxygen saturation of blood of a patient, which comprises applying a substance that enhances perfusion of blood to a predetermined location on the skin of the patient without using an iontophoresis method. A method comprising: placing a pulse oximeter sensor in its place; and measuring the oxygen saturation of the patient's blood with the pulse oximeter sensor. 2. The method of claim 1, wherein the blood perfusion enhancing substance is a cream consisting of methyl salicylate. 3. The method of claim 2, wherein the blood perfusion enhancing substance further comprises menthol. 4. A method for optically measuring the properties of blood of a patient, wherein a blood perfusion enhancing substance selected from a group of surface stimulants is applied to a patient's skin without the use of iontophoresis. Applying a sensor consisting of a light source and a photoelectric detector to a predetermined area of the patient's skin; transmitting light from the light source to the patient's tissue in the predetermined area; Measuring light with a photoelectric detector in a predetermined area. 5. A pulse oximeter sensor system comprising: a pulse oximeter sensor, means for contacting the pulse oximeter sensor with a sensing location on a patient's skin, and means for applying a blood perfusion enhancing substance to the sensing location. A system consisting of ,. 6. The system according to claim 5, wherein the contact means and the application means are adhesive patches. 7. The system of claim 6, wherein the adhesive patch has holes through which light can pass from the pulse oximeter sensor.