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.

1 . A device for contacting a surface of a patient's body to determine a physiologic parameter of the patient, comprising: 
 a probe including a means for preventing application of excessive pressure to a sensing site adjacent a measurement region in a tissue to allow for substantially undisturbed blood flow in the tissue; and    a sensor housed within the probe, the sensor responsive to the physiologic parameter, wherein the sensor is located within a sensing area of the probe.    
     
     
         2 . The device of  claim 1 , wherein the probe further comprises a means for reducing interference in the sensing area.  
     
     
         3 . The device of clam  2 , wherein the means for reducing interference in the sensing area is an integral portion of the probe.  
     
     
         4 . The device of  claim 1 , wherein the probe is constructed to allow the sensor to be secured at the sensing site adjacent to the measurement region in the tissue.  
     
     
         5 . The device of  claim 4 , wherein a surface of the probe is secured to the sensing site with an adhesive.  
     
     
         6 . The device of  claim 1 , wherein the sensor is detachable from the probe.  
     
     
         7 . The device of  claim 2 , wherein the means for reducing interference is adapted to reduce interference from electromagnetic radiation.  
     
     
         8 . The device of  claim 2 , wherein the interference reducing means comprises an isolating means for preventing an analyte from dissipating from the sensing area and for allowing the analyte to come into equilibrium within the sensing area.  
     
     
         9 . The device of  claim 8 , wherein the isolating means represents an integral portion of the probe.  
     
     
         10 . The device of  claim 9 , wherein the isolating means is sized to fit into the nares, mouth, or cheek of the patient.  
     
     
         11 . The device of  claim 1 , wherein the physiologic parameter to which the sensor is responsive is an analyte, blood flow rate, tissue temperature or tissue pH.  
     
     
         12 . The device of  claim 11 , wherein the analyte is a measurable quantity of the analyte.  
     
     
         13 . The device of  claim 12  wherein the analyte is selected from the group consisting of tissue pH, temperature, CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         14 . The device of  claim 11 , wherein the analyte is a measurable concentration of the analyte.  
     
     
         15 . The device of  claim 14 , wherein the analyte is selected from the group consisting of tissue pH, temperature, CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         16 . The device of  claim 14 , further comprising an indicating means operably connected to the sensor for indicating analyte concentration in the patient.  
     
     
         17 . The device of  claim 1 , wherein at least a portion of the probe comprises a material that allows the portion to deform in response to force applied to the probe so as to avoid substantial blanching the tissue.  
     
     
         18 . The device of  claim 17 , wherein the material is an elastically deformable polymer selected from the group consisting of polyethylene, polypropylene, polybutylene, polyamide, polyimide, polyester, perfluorinated polymer, polystyrene, polyvinyl chloride and elastomers.  
     
     
         19 . The device of  claim 1 , wherein the device includes a holding means for securing the probe to a sensing site adjacent to a measurement region in the tissue.  
     
     
         20 . The device of  claim 19 , wherein the holding means is selected from the group consisting of a clip, handle, clamp, adhesives, gels, fasteners, strap, belt, hook, sutures, and staples.  
     
     
         21 . The device of  claim 19 , wherein the holding means is adapted to secure the probe to the sensing site without applying a pressure greater than about 1.5×10 4  pascals to the tissue.  
     
     
         22 . The device of  claim 12 , wherein the analyte to which the sensor is responsive is a gas selected from the group consisting of oxygen, carbon dioxide, nitrous oxide, desflurane, enfluran, halothane, isoflurane, methoxyflurane, and sevoflurane.  
     
     
         23 . The device of  claim 1 , further comprising at least one additional sensor.  
     
     
         24 . The device of  claim 1 , wherein the device further comprises a temperature detecting means for detecting temperature at the sensor.  
     
     
         25 . The device of  claim 24 , wherein the temperature detecting means is detachable from the device.  
     
     
         26 . The device of  claim 12 , further comprising a sheath covering the device.  
     
     
         27 . The device of  claim 26 , wherein the device is adapted for single use.  
     
     
         28 . The device of  claim 26 , wherein the sheath has a selectively permeable portion that allows transmission of an analyte therethrough.  
     
     
         29 . The device of  claim 28 , wherein the selectively permeable portion is selected from the group consisting of a silicone, a porous membrane and combinations thereof.  
     
     
         30 . The device of  claim 26 , wherein the sheath includes a rigid portion.  
     
     
         31 . The device of  claim 26 , wherein the sheath is disposable.  
     
     
         32 . The device of  claim 23 , wherein the device is adapted for multiple use.  
     
     
         33 . The device of  claim 1 , wherein the tissue is nonepidermal.  
     
     
         34 . The device of  claim 33 , wherein the tissue is mucosal.  
     
     
         35 . The device of  claim 1 , wherein the sensing site is the patient's epidermis.  
     
     
         36 . The device of  claim 1 , wherein the sensor is a Severinghaus-type sensor.  
     
     
         37 . The device of  claim 14 , wherein the sensor is responsive to analyte concentration through a chemical reaction with a reactant.  
     
     
         38 . The device of  claim 37 , wherein the analyte concentration is the concentration of an analyte selected from the group consisting of tissue pH, temperature, CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         39 . The device of  claim 14 , wherein the sensor is responsive to analyte concentration through absorption, emission or modification of electromagnetic radiation within the tissue.  
     
     
         40 . The device of  claim 39 , wherein the analyte concentration is the concentration of an analyte selected from the group consisting of tissue pH, temperature, CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         41 . The device of  claim 39 , wherein the electromagnetic radiation is ultraviolet, visible, near infrared, or far infrared.  
     
     
         42 . The device of  claim 14 , wherein the sensor is responsive to analyte concentration through generation or alteration of an electrical current.  
     
     
         43 . The device of  claim 42 , wherein the analyte concentration is the concentration of an analyte selected from the group consisting of CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         44 . A method for determining a physiologic parameter of a patient, the method comprising: 
 (a) providing a probe having a sensor responsive to the physiologic parameter;    (b) placing the probe on a sensing site adjacent to a measurement region of a bodily tissue without substantially disturbing blood flow within the tissue; and    (c) detecting the response of the sensor to the physiologic parameter.    
     
     
         45 . The method of  claim 44 , wherein the physiologic parameter to which the sensor is responsive is an analyte, blood flow rate, tissue temperature or tissue pH.  
     
     
         46 . The method of  claim 45 , further comprising, before or after step (b), exposing the sensor to at least one analyte at a predetermined concentration in at least one calibrant.  
     
     
         47 . The method of  claim 46 , wherein the at least one analyte is selected from the group consisting of CO 2 , pCO 2 , O 2 , glucose, pyruvate, acetyl-CoA, citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, ADP, ATP, succinate, fumarate, malate oxaloacetate, NAD, NADH, and combinations thereof.  
     
     
         48 . The method of  claim 44 , wherein step (b) includes allowing the probe to contact the sensing site adjacent to a measurement region of the tissue so as to completely or substantially enclose the sensor within the sensing area.  
     
     
         49 . The method of  claim 48 , wherein the sensing site is mucosal tissue.  
     
     
         50 . The method of  claim 48 , wherein the sensing site is an epidermal surface of the patient's body.  
     
     
         51 . The method of  claim 45 , further comprising, after step (b) and before (c) allowing the concentration of an analyte in the sensing area to reach an equilibrium level.  
     
     
         52 . The method of  claim 44 , wherein step (b) further comprises substantially immobilizing the device on the sensing site for a predetermined period.  
     
     
         53 . The method of  claim 52 , wherein step (c) is initiated, repeated or performed continuously during the predetermined period of time.  
     
     
         54 . The method of  claim 44 , further comprising (d) correlating the response of the sensor to a condition of the patient.  
     
     
         55 . The method of  claim 54 , wherein the condition is a regional condition, a systemic condition, perfusion failure, tissue gas concentration, tissue pH or tissue activity.  
     
     
         56 . The method of  claim 54 , wherein step (d) is carried out using a predictive algorithm, endpoint detection and/or verification, and/or univariate, multivariate, or neural network analysis.