| Noninvasive detection of a physiologic parameter with a probe -> Monitor Keywords |
|
|
  Noninvasive detection of a physiologic parameter with a probeUSPTO Application #: 20060020179Title: Noninvasive detection of a physiologic parameter with a probe Abstract: The invention provides a device for contacting a surface of a patient's body to determine a physiologic parameter in a measurement region of a tissue of the patient. The device typically comprises a sensor responsive to the physiologic parameter and a probe housing the sensor. The probe is constructed to allow the sensor to be secured at a sensing site adjacent to the measurement region, without disturbing the blood flow within the measurement region of the tissue. The device may also include a means for reducing interference in the sensing area. Preferably, the device further comprises an indicating means operably connected to the sensor for indicating an analyte quantity and/or concentration associated with the physiologic parameter. (end of abstract) Agent: Oppenheimer Wolff & Donnelly LLP - Minneapolis, MN, US Inventors: Edward J. Anderson, Brandon W. Reynolds, Kent R. Winger, Victor E. Kimball USPTO Applicaton #: 20060020179 - Class: 600309000 (USPTO) Related Patent Categories: Surgery, Diagnostic Testing, Measuring Or Detecting Nonradioactive Constituent Of Body Liquid By Means Placed Against Or In Body Throughout Test The Patent Description & Claims data below is from USPTO Patent Application 20060020179. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. application Ser. No. 10/366,903, filed Feb. 14, 2003, now abandoned, which is a continuation-in-part of U.S. application Ser. No. 10/162,028, filed Jun. 3, 2002, now abandoned, the entireties of which are hereby incorporated by reference. TECHNICAL FIELD [0002] The present invention relates generally to devices and methods for noninvasive detection of a physiologic parameter within a tissue of a patient. More particularly, the invention relates to such devices and methods that allow a probe containing at least one sensor to be placed adjacent to a surface of the tissue, without substantially disturbing blood flow in the tissue, and/or without interference from interfering fluids or radiation. BACKGROUND [0003] There is a continuing need for improved devices and methods for determining one or more physiologic parameters of a patient. Often, such physiologic parameters are determined by detecting or measuring the quantity of concentration of an analyte associated with the physiologic parameter within a tissue of a patient. Noninvasive techniques for analyte detection are preferred over invasive detection techniques because invasive procedures result in stress and discomfort to patients. For example, conventional detection of blood analytes often involves drawing a sample of blood from the patient and subjecting the sample to in vitro testing for a specific analyte. This technique suffers from a number of drawbacks. First, drawing blood requires the puncturing of a patient's skin and creates a risk of infection. Second, hypodermic needles used in drawing blood may also pose a risk of accidental infection to health care professionals such as phlebotomists who routinely use the needles and sanitary workers who handle contaminated needles. Third, the technique of drawing blood and in vitro testing is not easily adaptable for real-time and continuous monitoring of changes in analyte. [0004] Nevertheless, analyte detection is of course an essential process in medical diagnosis. For example, it is necessary to determine the concentration of glucose in blood in diabetic patients on a regular basis. U.S. Pat. No. 5,771,891 to Gonzani describes a non-invasive blood analyte concentration monitoring apparatus for analyzing blood analytes such as glucose. This patent describes an apparatus that operates by stimulating an endogenous tissue with an electrical or magnetic stimulus, detecting a response of the tissue to the stimulus, correlating the response to a quantitative measure of the analyte concentration, and indicating the quantitative measure. It may also be desirable to measure the hematocrit concentration to determine the oxygen carrying capacity of a patient's blood. U.S. Pat. No. 5,372,136 to Steuer et al. describes a method for determining the concentration of a blood analyte such as hematocrit by passing at least two, preferably three, predetermined wavelengths of light onto or through body tissues such as the finger, earlobe or scalp and using mathematical manipulation of the detected values to compensate for spectral interference resulting from the presence of numerous species in body tissue. [0005] There is also widespread interest in blood gas concentration for a number of reasons. For example, a patient may be rendered unconscious during surgery through administration of gaseous anesthesia such as nitrous oxide, desflurane, enflurane, halothane, isoflurane, methoxyflurane or sevoflurane. These gases are administered by allowing the patient to inhale the gases into his or her lungs. Once the gas is in the circulatory system, it passes through the blood-brain barrier into the brain where the gas increases the neurocellular threshold for firing. The partial pressure of gas in the blood provides an indication of the pharmacodynamics of the gas with respect to the brain such as change in neurological metabolic rate. Thus, analyzing blood with respect to anesthesia content is useful to ensure that the patient is neither overly sedated nor insufficiently anesthetized. Excessive sedation may cause permanent injury to the patient, sometimes resulting in death, and insufficient sedation is ineffective to suppress pain. [0006] As another example, very low blood flow, or low "systemic perfusion," occurs typically because of low aortic pressure and can be caused by a number of factors, including hemorrhage, sepsis, and cardiac arrest. The body responds to such stress by reducing blood flow to the gastrointestinal tract to spare blood for other, more critical organs. Thus, when blood flow from the heart is reduced, blood flow is generally maintained to critical organs, such as the brain, which will not survive long without a continuous supply of blood, while blood flow is restricted to less critical organs, whose survival is not as threatened by a temporary reduction in blood flow. For example, blood flow to the stomach, intestines, esophagus and oral/nasal cavity is drastically reduced when there is a reduced blood flow from the heart or when a patient is experiencing circular shock. For this reason, decreased blood flow to the splanchnic blood vessels provides an indication of perfusion failure in a patient. Physicians commonly take advantage of this phenomenon by taking CO.sub.2 and pH measurements in the stomach and intestine to assess perfusion failure. [0007] Assessment of CO.sub.2 concentration in the less critical organs, i.e., those organs to which blood flow is reduced during perfusion failure, has also been useful in perfusion assessment. Carbon dioxide production, which is associated with metabolism, continues in tissues even during conditions of low blood flow. The concentration of CO.sub.2 builds up in tissues experiencing low blood flow because CO.sub.2 is not rapidly carried away. Correspondingly, O.sub.2 is consumed as CO.sub.2 is generated. This CO.sub.2 build-up (an increase in partial pressure of CO.sub.2 (pCO.sub.2)) in the less critical organs in turn results in a decrease in pH. Therefore, perfusion failure is commonly assessed by measuring pH or pCO.sub.2 at these sites, especially in the stomach and intestines. For examples of catheters used to assess pH or pCO.sub.2 in the stomach or intestines, see, e.g., U.S. Pat. Nos. 3,905,889; 4,016,863; 4,632,119; 4,643,192; 4,981,470; 5,105,812; 5,117,827; 5,174,290; 5,341,803; 5,411,022; 5,423,320; 5,456,251; and 5,788,631. [0008] A number other patents discuss the measurement tissue analytes. U.S. Pat. No. 5,579,763 to Weil et al., for example, discusses a minimally invasive method for detecting a chemical characteristic in the gastrointestinal system of a patient who is in critical condition. In this patent, the specification focuses on taking measurements of carbon dioxide in a patient's esophagus using a catheter having a carbon dioxide sensor at its tip. Similarly, U.S. Pat. No. 6,055,447 to Weil also relate to carbon dioxide measurements and describes that the sensor may be placed against mucosal surface in the mouth or nose other than the sublingual area. In addition, U.S. Pat. No. 6,216,024 to Weil et al. discusses a device for assessing perfusion failure that comprises a carbon dioxide sensor for lying against a mucosal surface of the upper digestive/respiratory tract of a patient, an isolating means for inhibiting air flow around the mucosal surface, and indicating means operatively connected to the sensor for indicating a degree of perfusion failure of the patient. [0009] Similarly, it is important to be able to accurately determine the amount of oxygen in the bloodstream or the amount of oxygen in the surrounding tissue. For example, PO.sub.2 in blood may be analyzed by using an oxygen electrode based on the so-called Clark's electrode system, described in U.S. Pat. No. 5,710,371 to Czernecki et al. Such electrode systems are based on electrochemical reduction of O.sub.2 at an anode made from an element such as tungsten or molybdenum. This type of analyte-sensitive portion requires the diffusion of O.sub.2 from blood across a membrane to a liquid electrolyte in which O.sub.2 is reduced at the anode/electrolyte interface, thereby generating an electrical current that corresponds to the PO.sub.2 in the blood sample. However, improper maintenance may subject the liquid electrolyte to evaporation or drying, thereby compromising the accuracy of analyte detection. Thus, this approach suffers from the drawback that the electrode apparatus must be meticulously maintained. [0010] U.S. Pat. No. 5,423,320 to Salzman et al. describes a method for measuring or monitoring intraluminal gastrointestinal pCO.sub.2 and pO.sub.2. The method involves providing a catheter having a gas sensor, a CO.sub.2 and/or an O.sub.2 sensor, at a distal tip that is placed within a patient. The sensor is coupled to an output signal generator and/or recorder external to the patient. The catheter may, for example, be a nasojejunal orjejunostomy catheter, wherein the tip of the catheter is placed adjacent to patient tissue, e.g., stomach, colon, rectum, or jejunum tissue, to detect for tissue analyte in situ. Improper placement of such a sensor through use of the catheter may cause blanching of the tissue in which analyte is measured, i.e., occlusion of fluid flow therein, Moreover, during use, this type of device is highly susceptible to being inadvertently rotated to an improper angle or otherwise moved out of proper position for accurate analyte detection. [0011] Thus, there is a need for a device to detect regional (local) or global (systemic) tissue perfusion in a number of contexts. Such devices may be used, for example, as a continuous monitor for extended time periods associated with surgical procedures and with recovery in an intensive care unit that involves a lengthy stay. Alternatively, a single-use version of such a device may be more appropriate for triage use in an emergency room or nursing home. In each of these applications, different CO.sub.2 and/or O.sub.2 sensing means and different product configurations may be more appropriate depending on the applications requirements for ease-of-use, cost, and response time. For example, either a single use sensor/probe that is discarded after every use or a reusable sensor/probe with or without a disposable sheath to minimize cross-contamination between patients may be utilized. In either case, an indicating means may be provided that is integral to the devices or linked to the device via an electronic, optical, or electromagnetic radiation means. However, since therapeutic decisions may be made based on the sensor readings, the sensor must accurately respond to analytes within tissue and not be compromised by ambient air or other contaminants. [0012] There are a number of challenges associated with the accuracy of non-invasive detection of CO.sub.2 and/or O.sub.2 in exposed tissue. Referring to CO.sub.2 detection as an example, a patient's tissue and surrounding ambient air often exhibit large differences in their respective concentrations of CO.sub.2 and O.sub.2. If a tissue with a high concentration of CO.sub.2 is exposed to ambient air with a low concentration of CO.sub.2, a measured CO.sub.2 value at the surface of the tissue will have a concentration between the high and the low. This difference can be small or large depending on the how analyte from the deeper tissue diffuses to the surface tissue, how the analyte diffuses from the surrounding environment into the tissue, the physical properties of the tissue, and whether normal blood flow is maintained in the tissue. [0013] It has now been discovered that various factors may compromise the usefulness or accuracy of measurement for certain tissue analytes associated with useful physiologic parameters, in particular, gaseous analytes such as O.sub.2 and CO.sub.2. For example, as noted above, tissue blanching tends to decrease the concentration of O.sub.2 in the blanched area, and a sensor may also be moved out of proper position during measurement. Thus, there is a need in the art for a device for accurate, useful yet noninvasive detection of an analyte, particularly a gaseous analyte, within a tissue of a patient. Such a device would be useful, e.g., to measure perfusion failure or to monitor the concentration of anesthesia during surgery. SUMMARY OF THE INVENTION [0014] Accordingly, it is an object of the present invention to overcome the above-mentioned disadvantages of the prior art by providing a device that provides for non-invasive and accurate determination of a physiologic parameter of a patient within a tissue of a patient. [0015] It is another object of the invention to provide a device that can be used to measure physiologic parameters locally/regionally and/or globally/systemically. [0016] It is another object of the invention to provide a device that can be used to measure physiologic parameters including respiratory, mechanical and metabolic. [0017] It is another object of the invention to provide a device that can be used to measure physiologic parameters such as O.sub.2 saturation levels. [0018] It is another object of the invention to provide a device that can be used to measure physiologic parameters such as pulse, blood flow, blood pressure and other parameters associated with a beating heart. [0019] It is another object of the invention to provide a device that can be used to measure physiologic parameters such as tissue analytes including carbon dioxide, oxygen, and anesthetic gases. It is a further object of the invention to provide a method to measure other physiologic parameters through the use of such a device such as glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and all other analytes associated with the tricarboxylic acid cycle. [0020] Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by routine experimentation during the practice of the invention. Continue reading... Full patent description for Noninvasive detection of a physiologic parameter with a probe Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Noninvasive detection of a physiologic parameter with a probe patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Noninvasive detection of a physiologic parameter with a probe or other areas of interest. ### Previous Patent Application: System and method for assessing sleep quality Next Patent Application: Device and method for monitoring body fluid and electrolyte disorders Industry Class: Surgery ### FreshPatents.com Support Thank you for viewing the Noninvasive detection of a physiologic parameter with a probe patent info. IP-related news and info Results in 8.17191 seconds Other interesting Feshpatents.com categories: Accenture , Agouron Pharmaceuticals , Amgen , AT&T , Bausch & Lomb , Callaway Golf |
||
