Cut-to-length sensing catheter and method thereof

Abstract

A sensing catheter cut to a predetermined length has sensing capabilities and methods. For example, the sensing catheter can include a catheter tube having temperature sensors along its initial length. Each temperature sensor can be independently electronically addressed, thereby maintaining the temperature sensing capabilities of the sensing catheter despite cutting any one or more of the temperature sensors along the distal length of the catheter tube when the catheter tube is cut from the initial length to the working length. Such a sensing catheter can further include strain sensors paired with the temperature sensors along the initial length of the catheter tube, allowing temperature measurement uncertainty at any temperature sensor to be compensated for by local strain measurements. Such a sensing catheter can further include lactate sensors paired with the temperature sensors, allowing enzyme activity, and therefore lactate concentration, associated with any lactate sensor to be normalized by at least local temperature compensation.

Description

[Background technology]

[0001] Catheters, such as central venous catheters (CVCs), peripherally inserted central catheters (PICCs), midline catheters, and peripheral intravenous catheters (PIVCs), are indwelling medical devices for administering medication, drawing blood, and the like. Because these catheters are indwelling medical devices, they may sense and transmit electrical signals associated with different physiological parameters of clinical interest. However, such catheters, particularly PICCs, are cut to a predetermined length before placement within a patient. This often makes it difficult to incorporate sensing sensors at multiple locations on the catheter that are best suited for sensing. In fact, sensing with a PICC is often optimal within the distal end of the PICC in terms of proximity to the patient's heart, yet it is the distal end of the PICC that is cut when the PICC is cut to a predetermined length before placement within the patient. What is needed is a sensing catheter with a properly positioned sensor that can be cut to a predetermined length without compromising sensing capabilities. Summary of the Invention [Means for solving the problem]

[0002] Disclosed herein is a cut-to-length sensing catheter and method that addresses the foregoing. Disclosed herein, in some embodiments, is a cut-to-length temperature sensing catheter including a catheter hub, a catheter tube including a plurality of temperature sensors, and one or more operably connected extension legs. The catheter tube has a proximal end portion inserted into a bore in the distal portion of the catheter hub. The plurality of temperature sensors are disposed within or on the surface of the catheter tube along its initial length. Each of the plurality of temperature sensors is independently electronically addressed with a corresponding temperature sensor electrical lead leading thereto. This allows the temperature sensing capability of the sensing catheter to be maintained despite cutting any one or more of the plurality of temperature sensors along with the distal length of the catheter tube when the catheter tube is cut from the initial length to the working length. Each of the one or more extension legs has a distal end portion inserted into the proximal portion of the catheter hub.

[0003] In some embodiments, the multiple temperature sensors may be multiple nested thermocouples. In some embodiments, each thermocouple of the plurality of thermocouples comprises a longitudinal loop formed between two wires of different thermocouple conductors having distal portions disposed within or on the surface of the catheter tube, the two wires terminating distally at hot junctions within or on the surface of the catheter tube.

[0004] In some embodiments, the two electrical leads have proximal portions disposed in or on the exterior surface of the catheter hub, and the two electrical leads terminate proximally at a cold junction on the printed circuit board assembly of the catheter hub.

[0005] In some embodiments, proximal portions of the two electrical leads extend from the exterior surface of the catheter hub into the bore of the catheter hub, and the proximal portions of the two electrical leads within the bore of the hub form electrical junctions with distal end portions of the two electrical leads where the proximal portion of the catheter tubing is inserted into the bore of the catheter hub.

[0006] In some embodiments, the two-wire thermocouple conductor is a conductive polymer. In some embodiments, the plurality of temperature sensors are a plurality of resistance temperature detectors (RTDs).

[0007] In some embodiments, each RTD in the plurality of RTDs includes a temperature sensitive element of the RTD conductor formed in or on the surface of the catheter tube with a known temperature vs. resistance relationship, such that any electrical resistance measured across the temperature sensitive element can be converted to a temperature.

[0008] In some embodiments, the RTD conductor is nanoscale structured silver or gold. In some embodiments, the sensing catheter further includes a plurality of strain sensors disposed in or on the surface of the catheter tube along its initial length, each of the plurality of strain sensors being independently electronically addressed by a corresponding strain sensor electrical lead thereto, thereby allowing the strain sensing capability of the sensing catheter to be maintained despite cutting off any one or more of the plurality of strain sensors along with the distal length of the catheter tube when cutting the catheter tube from the initial length to the working length.

[0009] In some embodiments, the plurality of strain sensors and the plurality of temperature sensors are each paired along the initial length of the catheter tube, allowing temperature measurement uncertainties due to strain-induced non-uniformities in any one of the plurality of temperature sensors to be corrected by the local strain measurements.

[0010] In some embodiments, each strain sensor of the plurality of strain sensors includes a patterned strain-sensitive element of a strain sensor conductor formed in or on the surface of the catheter tube, having a length along the length of the catheter tube, such that any change in electrical resistance due to tension, which increases the resistance, or compression, which decreases the resistance, across the patterned strain-sensitive element induced by bending of the catheter tube can be measured.

[0011] In some embodiments, the strain sensor conductor is nanoscale structured silver or gold. In some embodiments, the surface of the catheter tube independently comprises the abluminal surface or the luminal surface of the catheter tube.

[0012] In some embodiments, the sensing catheter further includes an electrical connector configured to connect the sensor electronics of the sensing catheter to the console and to relay electrical signals to the sensing catheter, relay electrical signals from the sensing catheter, or both.

[0013] In some embodiments, the sensing catheter is a CVC, a PICC, a midline catheter, or a PIVC. Disclosed herein, in some embodiments, is a cut-to-length lactate sensing catheter that includes a catheter hub, a catheter tube containing multiple lactate sensors, and one or more operably connected extension legs. The catheter tube has a proximal end portion that is inserted into a bore in the distal end portion of the catheter hub. The multiple lactate sensors are disposed within or on the surface of the catheter tube along its initial length. Each lactate sensor of the multiple lactate sensors is independently electronically addressed with a corresponding lactate sensor electrical lead leading thereto. This allows the lactate sensing capability of the sensing catheter to be maintained despite cutting off any one or more lactate sensors of the multiple lactate sensors along with the distal length of the catheter tube when cutting the catheter tube from the working length. Each extension leg of the one or more extension legs has a distal end portion that is inserted into the proximal portion of the catheter hub.

[0014] In some embodiments, each lactate sensor of the plurality of lactate sensors comprises either a three-electrode sensor or a two-electrode sensor. A three-electrode sensor comprises a working electrode, a reference electrode, and a counter electrode. A two-electrode sensor comprises a working electrode and a reference electrode.

[0015] In some embodiments, each lactate sensor of the plurality of lactate sensors comprises a two-electrode sensor covered with an anti-fouling membrane. The working electrode comprises a layered working electrode structure with a metal layer beneath a conductive polymer layer having an immobilized enzyme therein or thereon. The reference electrode comprises a reference electrode structure with a metal layer, which may be the same as or different from the working electrode, beneath a metal salt layer.

[0016] In some embodiments, the sensing catheter further includes a plurality of temperature sensors disposed in or on the surface of the catheter tube along its initial length, each temperature sensor of the plurality of temperature sensors being independently electronically addressed by a corresponding temperature sensor electrical lead thereto, thereby allowing the temperature sensing capability of the sensing catheter to be maintained despite any one or more of the plurality of temperature sensors being cut off along with the distal length of the catheter tube when the catheter tube is cut from the initial length to the working length.

[0017] In some embodiments, the temperature sensors and lactate sensors are paired along the initial length of the catheter tube, allowing the enzyme activity, and therefore the lactate concentration, associated with any one of the lactate sensors to be normalized by at least local temperature compensation.

[0018] In some embodiments, the plurality of temperature sensors is a plurality of nested thermocouples. In some embodiments, each thermocouple of the plurality of thermocouples comprises a longitudinal loop formed between two wires of different thermocouple conductors having distal portions disposed within or on the surface of the catheter tube, the two wires terminating distally at hot junctions within or on the surface of the catheter tube.

[0019] In some embodiments, the two electrical leads have proximal portions disposed in or on the exterior surface of the catheter hub, and the two electrical leads terminate proximally at a cold junction on the printed circuit board assembly of the catheter hub.

[0020] In some embodiments, proximal portions of the two electrical leads extend from the exterior surface of the catheter hub into the bore of the catheter hub, and the proximal portions of the two electrical leads within the bore of the hub form electrical junctions with distal portions of the two electrical leads where the proximal end portion of the catheter tubing is inserted into the bore of the catheter hub.

[0021] In some embodiments, the two-wire thermocouple conductor is a conductive polymer. In some embodiments, the multiple temperature sensors are multiple RTDs. In some embodiments, each RTD in the plurality of RTDs includes a temperature sensitive element of the RTD conductor formed in or on the surface of the catheter tube with a known temperature vs. resistance relationship, such that any electrical resistance measured across the temperature sensitive element can be converted to a temperature.

[0022] In some embodiments, the RTD conductor is nanoscale structured silver or gold. In some embodiments, the sensing catheter further includes a plurality of strain sensors disposed in or on the surface of the catheter tube along its initial length, each of the plurality of strain sensors being independently electronically addressed by a corresponding strain sensor electrical lead thereto, thereby allowing the strain sensing capability of the sensing catheter to be maintained despite cutting off any one or more of the plurality of strain sensors along with the distal length of the catheter tube when cutting the catheter tube from the initial length to the working length.

[0023] In some embodiments, the plurality of strain sensors and the plurality of temperature sensors are each paired along the initial length of the catheter tube, allowing temperature measurement uncertainties due to strain-induced non-uniformities in any one of the plurality of temperature sensors to be corrected by the local strain measurements.

[0024] In some embodiments, each strain sensor of the plurality of strain sensors comprises a patterned strain-sensitive element of a strain sensor conductor formed in or on the surface of the catheter tube with a length along the length of the catheter tube, such that any change in electrical resistance due to tension, which increases the resistance, or compression, which decreases the resistance, across the patterned strain-sensitive element induced by bending of the catheter tube can be measured.

[0025] In some embodiments, the strain sensor conductor is nanoscale structured silver or gold. In some embodiments, the surface of the catheter tube independently comprises the luminal surface or the luminal surface of the catheter tube.

[0026] In some embodiments, the sensing catheter further includes an electrical connector configured to connect the sensor electronics of the sensing catheter to the console and to relay electrical signals to the sensing catheter, relay electrical signals from the sensing catheter, or both.

[0027] In some embodiments, the sensing catheter is a CVC, a PICC, a midline catheter, or a PIVC. Also disclosed herein, in some embodiments, is a method of using a sensing catheter, the method including a trimming step, a catheter tube advancing step, and a sensor data reading step. The trimming step includes trimming a distal length of the catheter tube from its initial length to reduce the catheter tube to a working length. Trimming the distal length of the catheter tube also trims one or more sensors disposed in or on the surface of the catheter tube. The catheter tube advancing step includes advancing a distal portion of the catheter tube into a vascular lumen of a patient to a desired location within the patient's body. The sensor data reading step includes reading sensor data from one or more sensors to determine an instantaneous state of the patient.

[0028] In some embodiments, the catheter tube includes multiple lactate sensors disposed within or on the surface of the catheter tube along its initial length, each lactate sensor of the multiple lactate sensors being independently electronically addressed with a corresponding lactate sensor electrical lead thereto, allowing one or more sensors to be trimmed along with the distal length of the catheter tube while still maintaining the lactate sensing capability of the sensing catheter.

[0029] In some embodiments, the catheter tube further includes a plurality of temperature sensors disposed within or on the surface of the catheter tube along its initial length, each temperature sensor of the plurality of temperature sensors being independently electronically addressed by a corresponding temperature sensor electrical lead thereto, thereby allowing one or more sensors to be trimmed along with the distal length of the catheter tube while still maintaining the temperature sensing capability of the sensing catheter.

[0030] In some embodiments, the temperature sensors and lactate sensors are each paired along the initial length of the catheter tube, allowing the enzyme activity, and therefore lactate concentration, associated with any lactate sensor of the lactate sensors to be normalized by at least local temperature compensation.

[0031] In some embodiments, the plurality of temperature sensors is a plurality of nested thermocouples. In some embodiments, the multiple temperature sensors are multiple RTDs. In some embodiments, the catheter tube further includes a plurality of strain sensors disposed within or on the surface of the catheter tube along its initial length, each of the plurality of strain sensors being independently electronically addressed by a corresponding strain sensor electrical lead thereto, thereby allowing the strain sensing capability of the sensing catheter to be maintained despite the truncation of one or more sensors along with the distal length of the catheter tube.

[0032] In some embodiments, the plurality of strain sensors and the plurality of temperature sensors are each paired along the initial length of the catheter tube, allowing temperature measurement uncertainties due to strain-induced non-uniformities in any one of the plurality of temperature sensors to be corrected by the local strain measurements.

[0033] In some embodiments, the method further includes connecting an electrical connector to the console to read sensor data from a display screen associated with the console, the electrical connector connecting the sensor electronics of the sensing catheter to the console and configured to relay electrical signals to the sensing catheter, relay electrical signals from the sensing catheter, or both.

[0034] These and other features of the concepts provided herein will become more apparent to those skilled in the art in view of the accompanying drawings and the following description, which set forth in detail specific embodiments of such concepts. [Brief explanation of the drawings]

[0035] [Figure 1] FIG. 1 illustrates a catheter sensing system including a console and a sensing catheter that is cut to length, according to some embodiments. [Figure 2A] FIG. 1 is a detailed view showing a first side of a sensing catheter, particularly a first side of a catheter tube of the sensing catheter, which side of the catheter tube includes both multiple temperature sensors and multiple strain sensors according to some embodiments. [Figure 2B] FIG. 10 is a detailed view showing a second side of the sensing catheter, particularly a second side of the catheter tube of the sensing catheter, which side of the catheter tube includes multiple lactate sensors according to some embodiments. [Figure 3A] FIG. 10 illustrates in more detail a first side of a catheter tube including one temperature sensor of a plurality of temperature sensors and one strain sensor of a plurality of strain sensors according to some embodiments. [Figure 3B] FIG. 10 illustrates in more detail a second side of the catheter tube including one lactate sensor of the plurality of lactate sensors according to some embodiments. [Figure 4] FIG. 10 is a detailed view showing a first side of a sensing catheter including an alternative multiple temperature sensors according to some embodiments. [Figure 5] 5 is a cutaway view showing the catheter hub of the sensing catheter of FIG. 4, including a proximal portion of a lead disposed in or on the outer surface of the catheter hub that extends into the bore of the catheter hub, according to some embodiments. [Figure 6] FIG. 6 is a detailed view showing a catheter tube inserted into the catheter hub of FIG. 5, including a distal portion of a wire disposed in or on the luminal surface thereof, the distal portion forming an electrical junction with a proximal portion of the wire extending into the bore of the catheter hub, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0036] Before some specific embodiments are disclosed in more detail, it should be understood that the specific embodiments disclosed herein do not limit the scope of the concepts provided herein. It should also be understood that the specific embodiments disclosed herein can have features that can be readily separated from the specific embodiment and, optionally, combined with or substituted for features of any of the other numerous embodiments disclosed herein.

[0037] Regarding the terms used herein, it should also be understood that the terms are intended to describe certain specific embodiments and do not limit the scope of the concepts provided herein. Ordinal numbers (e.g., first, second, third, etc.) are generally used to distinguish or identify different features or steps within a group of features or steps and do not provide sequential or numerical limitations. For example, "first," "second," and "third" features or steps do not necessarily have to appear in that order, and a particular embodiment including such features or steps is not necessarily limited to three features or steps. In addition, unless otherwise noted, any of the aforementioned features or steps can include one or more additional features or steps. Labels such as "left," "right," "top," "bottom," "front," "back," etc. are used for convenience and do not imply, for example, a particular fixed position, orientation, or direction. Instead, such designations are used to reflect, for example, a relative position, orientation, or direction. The singular forms "one," "one," and "said" also include plural references unless the context clearly dictates otherwise.

[0038] "Proximal" refers to a portion, section, piece, element, etc. of a medical device that is intended to be near or relatively near the clinician when the medical device is used on a patient. For example, a "proximal portion" or "proximal section" of a medical device includes a portion or section of the medical device that is intended to be near the clinician when the medical device is used on a patient. Similarly, a "proximal length" of a medical device includes the length of the medical device that is intended to be near the clinician when the medical device is used on a patient. A "proximal end" of a medical device includes the end of the medical device that is intended to be near the clinician when the medical device is used on a patient. The proximal portion, section, or length of a medical device need not include the proximal end of the medical device. In fact, the proximal portion, section, or length of a medical device may be shorter than the proximal end of the medical device. However, the proximal portion, proximal section, or proximal length of a medical device may include the proximal end of the medical device, in which case, unless otherwise indicated, the proximal portion, proximal section, or proximal length of the medical device may be further specified as the proximal end, proximal end section, or proximal end length of the medical device.

[0039] "Distal" refers to a portion, section, piece, element, etc. of a medical device that is intended to be near, relatively near, or within a patient when the medical device is used on a patient. For example, a "distal portion" or "distal section" of a medical device includes a portion or section of the medical device that is intended to be near, relatively near, or within a patient when the medical device is used on a patient. Similarly, a "distal length" of a medical device includes a length of the medical device that is intended to be near, relatively near, or within a patient when the medical device is used on a patient. A "distal end" of a medical device includes an end of the medical device that is intended to be near, relatively near, or within a patient when the medical device is used on a patient. A distal portion, section, or length of a medical device need not include the distal end of the medical device. In fact, a distal portion, section, or length of a medical device may be shorter than the distal end of the medical device. However, the distal portion, section, or length of a medical device may include the distal end of the medical device, in which case, unless otherwise indicated, the distal portion, section, or length of the medical device may be further identified as the distal end, section, or length of the medical device.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Catheters such as CVCs, PICCs, midline catheters, and PIVCs are indwelling medical devices for medication administration, blood sampling, and the like. Because these catheters are indwelling medical devices, they may sense and transmit electrical signals associated with different physiological parameters of clinical interest. However, such catheters, particularly PICCs, are cut to a predetermined length before placement within a patient. This often makes it difficult to incorporate sensing sensors at multiple locations on the catheter that are best suited for sensing. In fact, sensing with a PICC is often optimal within the distal end of the PICC in terms of proximity to the patient's heart, yet it is the distal end of the PICC that is cut when the PICC is cut to a predetermined length before placement within the patient. What is needed is a sensing catheter with appropriately located sensors that can be cut to a predetermined length without compromising sensing capabilities.

[0041] Disclosed herein are cut-to-length sensing catheters and methods that address the foregoing. Sensing System FIG. 1 illustrates a catheter-sensing system 100 including a console 102 and a sensing catheter 104 that is cut to length, according to some embodiments.

[0042] As shown, the console 102 may incorporate a display screen 106. However, the display screen 106 may instead be separate from and communicatively coupled to the console 102. Such a display screen 106 may be configured to provide a graphical user interface (GUI) for displaying information thereon, such as sensor data from the sensing catheter 104 and patient status based on the sensor data.

[0043] Although not shown, console 102 may include one or more processors and, optionally, memory containing instructions stored therein configured, when executed by the one or more processors, to instantiate one or more processes to control various functions of system 100 with specialized logic therefor.

[0044] The one or more processes may be configured to relay electrical signals from the console 102 to the sensing catheter 104, relay electrical signals from the sensing catheter 104 to the console 102, or both. In one example, the one or more processes may be configured to apply a voltage to the working electrode 132 of any of the plurality of lactate sensors 124 described below relative to the reference electrode 134, read a current from the working electrode 132 of the lactate sensor, or both. In another example, the one or more processes may be configured to send a higher voltage current to any of the plurality of RTDs 148 described below, receive a lower voltage current from any of the plurality of RTDs 148, or both. In another example, the one or more processes may be configured to apply a higher voltage to any of the plurality of strain sensors 128 described below, read a lower voltage from any of the plurality of strain sensors 128, or both. In another example, one or more processes may be configured to read the voltage from any of the plurality of thermocouples 150 .

[0045] Additionally or alternatively, one or more processes may be configured to automatically determine sensor measurements from electrical signals relayed from the sensing catheter 104 to the console 102. In one example, lactate concentration may be automatically and amperometrically determined using a current read from the working electrode 132 of any of the plurality of lactate sensors 124, the current being proportional to the lactate concentration. In another example, temperature may be automatically determined using a voltage drop read across any of the plurality of RTDs 148, the voltage drop corresponding to an electrical resistance which, in turn, corresponds to temperature given the known temperature-to-resistance relationship of the RTD conductor.

[0046] Finally, in addition or instead, the one or more processes may optionally be configured to aggregate sensor data from the sensor measurements to determine trends in the sensor data, determine an instantaneous patient state from the sensor data, and display the sensor data, the instantaneous patient state, or both on a display screen 106 as shown in FIG. 1 .

[0047] Although not shown, the console 102 may further include an electrical cable having an electrical connector configured to connect the console 102 to an external power source. Additionally or alternatively, the console 102 may include an internal power source (e.g., a battery). Whether the console 102 is configured for an external power source, an internal power source, or both, the console 102 may include power management circuitry for power regulation and distribution within the console 102 and to the sensing catheter 104.

[0048] In particular, the sensing catheter 104, as described below, may include an extension cable 120 and at least its proximal electrical connector 122. The extension cable 120 may be configured to connect the sensor electronics of the sensing catheter 104 to the console 102 to relay electrical signals from the console 102 to the sensing catheter 104, to relay electrical signals from the sensing catheter 104 to the console 102, or both. The extension cable 120 may also be configured to connect the sensing catheter 104 to the console 102 to power the sensing catheter 104. However, the extension cable 120 may instead be configured to connect the sensing catheter 104 to an external power source, as described below, and the electrical signals relayed from the console 102 to the sensing catheter 104, as well as the electrical signals relayed from the sensing catheter 104 to the console 102, may be relayed wirelessly. Additionally or alternatively, the sensing catheter 104 may include an internal power source as described below, and electrical signals relayed from the console 102 to the sensing catheter 104, as well as electrical signals relayed from the sensing catheter 104 to the console 102, may be relayed wirelessly.

[0049] Notwithstanding the foregoing, the system 100 need not include the console 102, as the sensing catheter 104 itself may be configured with visualization means for visualizing the sensor data, the patient's condition based on the sensor data, or both, an implanted system for controlling various functions of the system 100 or the sensing catheter 104, power circuitry, an internal power source (e.g., a battery), an extension cable 120 configured to connect the sensing catheter 104 to an external power source or both, or combinations thereof. For example, the visualization means of such a sensing catheter 104 may include an integrated display screen (e.g., a twisted nematic thin film transistor liquid crystal display ["TN TFT LCD"] display screen), one or more light-emitting diodes ("LEDs") configured to emit light in one or more colors, one or more patterns (e.g., a simple blinking pattern, a more complex blinking pattern with at least two different blinks, such as short blinks and long blinks), or a combination thereof, or both an integrated display screen and one or more LEDs to indicate the sensor data, the patient's condition based on the sensor data, or both. Further to this example, the sensing catheter 104 implantation system may include a catheter computer module (CCM) having one or more processors, a memory, and, optionally, a combination of instructions stored in the memory configured, when executed by the one or more processors, to instantiate one or more processes, such as those described above, to control various functions of the system 100 or the sensing catheter 104 with specialized logic therefor. Finally, the sensing catheter 104 may include an internal battery supply or battery.

[0050] Cut-to-length sensing catheter FIG. 1 is a general view of a sensing catheter 104 cut to length according to some embodiments.

[0051] As shown, the sensing catheter 104 may include a catheter hub 108, a catheter tube 110, and one or more operably connected extension legs 112. In practice, the catheter tube 110 may have a proximal end portion that is inserted into a bore 114 in the distal portion of the catheter hub 108 (see FIGS. 5 and 6 for more details). Such a catheter tube 110 may be formed from silicone, thermoplastic urethane, thermoplastic elastomer, or the like. Furthermore, the catheter tube 110 may have a coating such as a hydrophilic coating, a heparin coating, or a nitrous oxide-releasing coating. When the catheter tube 110 is coated with a hydrophilic coating, the hydrophilic coating may be polyvinylpyrrolidone (PVP), poly(2-hydroxyethyl methacrylate) (pHEMA), or polyethylene glycol (PEG) having a thickness of 1 to 50 μm, and may optionally be functionalized with heparin or an antimicrobial agent, such as silver, chlorhexidine, or one or more antimicrobial peptides. Each extension leg of the one or more extension legs 112 may have a distal end portion that is inserted into the proximal portion of the catheter hub 108, as well as a proximal end portion that is inserted into the distal portion of an extension leg connector 116 (e.g., a Luer connector). Such a sensing catheter 104 may be mono-lumen or multi-lumen, with at least one lumen 117 extending from a proximal opening in the extension leg connector to a distal opening at the catheter tip 118 of the catheter tube 110. Any other lumen may extend from another proximal opening in another extension leg connector to another distal opening in the side of the catheter tube 110.

[0052] In particular, a sensing catheter 104 having one or more lumens, such as lumen 117, establishes at least two surfaces of the sensing catheter 104: an inner surface and an outer surface of the sensing catheter 104. The inner surface and outer surface may alternatively be referred to herein as a luminal surface and an outer surface, respectively, particularly with respect to the catheter tube 110 or any extension legs of the one or more extension legs 112. Any surface referred to herein should be understood to be independently either an inner surface or luminal surface or an outer surface or an outer surface or an outer surface, unless the context suggests otherwise, without further reference to it being an inner surface or luminal surface or an outer surface or an outer surface. However, it should be understood that one or more sensors, as described below, on at least the exterior or luminal surface of the catheter tube 110, as opposed to those on the interior or luminal surface of the catheter tube 110, provide the advantage of being in direct contact with the sample (e.g., blood) containing the analyte (e.g., lactate), and preventing or at least mitigating temperature effects from cooler infusates delivered through one or more lumens, etc.

[0053] The sensing catheter 104 may also include an extension cable 120 having a distal electrical connector 122 and, optionally, a distal electrical connector configured to connect the extension cable 120 to the catheter hub 108 if the extension cable 120 is not fixedly connected to the catheter hub 108. The extension cable 120 may be configured to connect the sensor electronics of the sensing catheter 104 to the console 102 via the proximal electrical connector 122 to relay electrical signals from the console 102 to the sensing catheter 104, to relay electrical signals from the sensing catheter 104 to the console 102, or both. The extension cable 120 may also be configured to connect the sensing catheter 104 to the console 102 via the proximal electrical connector 122 to power the sensing catheter 104. In some embodiments, however, the extension cable 120 may be configured to connect the sensing catheter 104 to an external power source via the proximal electrical connector 122. In embodiments including a console 102, the electrical signals relayed from the console 102 to the sensing catheter 104, as well as the electrical signals relayed from the sensing catheter 104 to the console 102, may be relayed wirelessly.

[0054] While the sensing catheter 104 in FIG. 1 is a PICC, it should be understood that the sensing catheter 104 may instead be a CVC, midline catheter, PIVC, or any other vascular access device (VAD) ranging in diameter from at least 0.5 mm to 3.3 mm (1.4 to 10 French), given the application of the VAD to such devices that may benefit from the features of the sensing catheter 104 provided herein. Another embodiment of the sensing catheter 104 may also include a urinary catheter, such as a Foley catheter. However, a Foley catheter may be limited to the sole example of a sensor provided herein, given the inverted configuration of the sensing catheter 104 provided herein. Notably, neither the shape nor the stiffness of the sensing catheter 104 is appreciably altered from that of its non-sensing catheter counterpart by one or more of the multiple sensors described below. As such, a clinician can simply replace a non-sensing catheter with a sensing catheter 104 of the same type.

[0055] For convenience of explanation, one embodiment of the sensing catheter 104 having three individually electronically addressed sensors will be described herein, where each of the three sensors corresponds to a different sensing capability, and thus three different sensing capabilities, of the sensing catheter 104. As will become more apparent in view of the description below, each sensor of each of the three sensors being individually electronically addressed allows the sensing catheter 104 to maintain its three different sensing capabilities despite cutting off any one or more of the three sensors along with the distal length of the catheter tube 110 when cutting the catheter tube 110 from its initial length to its working length. And it should be understood that maintaining such sensing capabilities of the sensing catheter 104 when cutting the catheter tube 110 extends to each embodiment of the sensing catheter 104 provided herein, whether the sensing catheter 104 is a temperature sensing catheter including only a plurality of temperature sensors 126 or a multiple analyte sensing catheter including one or more other analyte sensors in addition to a plurality of lactate sensors 124.

[0056] The following embodiment of the sensing catheter 104 (i.e., a lactate sensing catheter with additional sensing capability for at least core body temperature Tc) includes a synergistic combination of three sensors: a plurality of lactate sensors 124, a plurality of temperature sensors 126, and a plurality of strain sensors 128. Indeed, as will become more apparent in view of the description below, temperature measurement uncertainty at any one of the plurality of temperature sensors 126 due to catheter bending and strain-induced non-uniformity can be corrected by the local strain measurement from the corresponding strain sensor. Similarly, enzyme activity, and therefore lactate concentration, associated with any one of the plurality of lactate sensors 124 can be normalized by at least local temperature compensation with the corrected temperature measurement from the corresponding temperature sensor. And, of course, in view of the above, each of the plurality of lactate sensors 124, the plurality of temperature sensors 126, and the plurality of strain sensors 128 being individually electronically addressed allows the lactate-, temperature-, and strain-sensing capabilities of the sensing catheter 104, and their synergistic effects, to be maintained despite any one or more of the aforementioned sensors being cut off along with the distal length of the catheter tube 110 when the catheter tube 110 is cut from its initial length to its working length.

[0057] Finally, it should be understood that the sensing catheter 104 is not limited to the lactate-sensing catheter described below. Indeed, other metabolite sensors (e.g., glucose, creatinine, etc.), or more generally, other analyte sensors in addition to or in place of the lactate sensors 124, may similarly benefit from being associated with the temperature sensors 126 and strain sensors 128 present in the sensing catheter 104. That said, in some embodiments, the sensing catheter 104 may include one or more of the aforementioned analyte sensors (e.g., lactate sensors 124) without the strain sensors 128 and without the temperature sensors 126, despite the synergistic combination illustrated by the lactate sensors 124, temperature sensors 126, and strain sensors 128. Such an embodiment of the sensing catheter 104 may have lower measurement accuracy, but may be less expensive to produce and therefore may be offered at a lower price. In some embodiments, the sensing catheter 104 need not include one or more of the aforementioned analyte sensors (e.g., lactate sensors 124). Indeed, with the understanding that omitting the multiple strain sensors 128 may make the sensing catheter 104 cheaper to produce but may result in lower measurement accuracy, the sensing catheter 104 may instead be simply a temperature sensing catheter for Tc, again with or without multiple strain sensors 128.

[0058] In particular, approximately 1.7 million people in the United States are diagnosed with sepsis each year, and of those people, approximately 270,000 die. Lactate is a key biomarker of sepsis and, for this reason, plays an important role in the detection, monitoring, and treatment of sepsis. Currently, blood samples are taken every 4 to 8 hours to measure biomarkers such as lactate in hospitalized patients at risk of sepsis. If sepsis is detected early and treated promptly in patients, mortality rates can improve by 7.6% every hour. Therefore, continuous monitoring of lactate, particularly in vivo monitoring of lactate using the sensing catheter 104 or another similarly configured VAD, can make a significant difference in clinical outcomes. Furthermore, continuous monitoring of Tc, particularly in vivo monitoring of Tc using the sensing catheter 104 or another similarly configured VAD, can make an even greater difference in clinical outcomes because changes in body temperature also play an important role in the detection, monitoring, and treatment of adverse conditions.

[0059] 2A and 3A show detailed views of a first side of the sensing catheter 104, specifically the first side of the catheter tube 110, which includes multiple temperature sensors 126 and multiple strain sensors 128 according to some embodiments. 2B and 3B show detailed views of a second side of the sensing catheter 104, opposite the first side, specifically the second side of the catheter tube 110, which includes multiple lactate sensors 124 according to some embodiments. As such, the sensing catheter 104 may include three multiple sensors, each corresponding to a different sensing capability, thus a total of three different sensing capabilities for the sensing catheter 104. However, it should be understood that the three multiple sensors may be distributed throughout the catheter tube 110 differently than in the foregoing figures. For example, three sensor sets, each of which may include a single lactate sensor, a single temperature sensor, and a single strain sensor in a row, may be distributed along the catheter tube 110 such that they spiral around the catheter with a period that is coextensive with the initial length of the catheter tube 110, a portion of the initial length of the catheter tube 110, or a multiple of the initial length of the catheter tube 110.

[0060] As shown, multiple lactate sensors 124 may be positioned in or on the surface of the catheter tube 110 along its initial length. Each lactate sensor of the multiple lactate sensors 124 is independently electronically addressed with a corresponding lactate sensor electrical lead 130 leading thereto. This allows the lactate sensing capability of the sensing catheter 104 to be maintained despite any one or more of the multiple lactate sensors 124 being cut off along with the distal length of the catheter tube 110 when the catheter tube 110 is cut from the initial length to the working length.

[0061] Each lactate sensor of the plurality of lactate sensors 124 may include, but is not limited to, a three-electrode or two-electrode lactate sensor on the microscale or smaller. For example, each electrode of a three-electrode or two-electrode sensor may range from a few micrometers in thickness to hundreds of micrometers in length or width. Each lactate sensor of a three-electrode or two-electrode sensor may include a working electrode 132 and a reference electrode 134. However, a three-electrode lactate sensor may further include a counter electrode. The working electrode 132 of at least a two-electrode lactate sensor may include, for example, a layered working electrode structure in which a metal layer 136 (e.g., silver, gold, or chromium) also has a nanoscale thickness (e.g., a few nanometers thick) is underneath a conductive polymer layer 138 (e.g., polypyrrole, poly(3,4-ethylenedioxythiophene) (PEDOT), PEDOT:polystyrenesulfonate (PSS) [i.e., PEDOT:PSS], PEDOT:Cl, etc.). The conductive polymer layer 138 includes an immobilized enzyme (e.g., lactate oxidase [LOD] or lactate dehydrogenase [LDH]) disposed within or on the surface of the conductive polymer layer 138, as illustrated by enzyme layer 139. The reference electrode 134 of the at least two-electrode lactate sensor may include a layered reference electrode structure in which a metal layer 140 (e.g., the same metal, such as silver) that is the same as or different from the working electrode 132 is located below a metal salt layer 142 (e.g., silver chloride), and each of the metal layer 140 and the metal salt layer 142 also has, for example, a nanoscale thickness. Regardless of whether each lactate sensor of the plurality of lactate sensors 124 includes a three-electrode lactate sensor or a two-electrode lactate sensor, each lactate sensor of the plurality of lactate sensors 124 may include an anti-fouling membrane 144 covering its upper side. The anti-fouling membrane 144 may be a thin (e.g., ≦1 μm) porous membrane configured to allow lactate molecules to pass through while simultaneously blocking biomolecules such as proteins, thereby allowing the sensing catheter 104 and its multiple lactate sensors to operate in the blood without contamination.

[0062] As further shown in Figures 2A, 2B, 3A, and 3B, multiple temperature sensors 126 may also be disposed in or on the surface of the catheter tube 110 along its initial length. Each temperature sensor of the multiple temperature sensors 126 is independently electronically addressed with a corresponding temperature sensor electrical lead 146 or two leads 154 of different thermocouple conductors leading thereto. This allows the temperature sensing capability of the sensing catheter 104 to be maintained despite any one or more of the multiple temperature sensors 126 being cut off along with the distal length of the catheter tube 110 when the catheter tube 110 is cut from its initial length to its working length. In particular, the multiple temperature sensors 126 and the multiple lactate sensors 124 are each paired along the initial length of the catheter tube 110. This allows the enzyme activity, and therefore the lactate concentration, associated with any of the multiple lactate sensors 124 to be normalized by at least local temperature compensation as enzyme activity increases with temperature.

[0063] The multiple temperature sensors 126 may be multiple RTDs 148 or multiple nested thermocouples 150 . 2A and 3A, each RTD in the plurality of RTDs 148 can include a temperature sensing element 152 (e.g., a planar coil with a diameter of ≦100 μm) of an RTD conductor formed in or on the surface of the catheter tube 110. The temperature sensing element 152 is specifically paired with a proximate lactate sensor in the plurality of lactate sensors 124. The RTD conductor of the temperature sensing element 152 has a known temperature-to-resistance relationship, allowing any electrical resistance measured across the temperature sensing element 152 to be converted to a temperature. In particular, the RTD conductor can be, but is not limited to, nanoscale-structured silver (e.g., silver nanowires, silver nanoparticles, etc.) or gold (e.g., gold nanowires, gold nanoparticles, etc.) disposed in or on the surface of the catheter tube 110, deposited (e.g., by electrochemical deposition, chemical vapor deposition, or physical vapor deposition), coated (e.g., by spray coating or spin coating), printed (e.g., by screen printing), etc. In fact, the RTD conductors may instead be thin films of platinum, nickel, or copper.

[0064] 4 shows a detailed view of a first side of a sensing catheter 104 including multiple thermocouples 150 according to some embodiments. However, it should be understood that the multiple thermocouples 150 may be more numerous and extend farther along the catheter tube 110 than those shown in FIG.

[0065] Continuing with the thermocouples shown in FIG. 4 , each thermocouple of the plurality of thermocouples 150 can include a longitudinal loop formed between two wires 154 of different thermocouple conductors, e.g., deposited (e.g., by electrochemical deposition, chemical vapor deposition, or physical vapor deposition), coated (e.g., by spray coating or spin coating), printed (e.g., by screen printing), etc., disposed within or on at least the surface of the catheter tube 110 having a microscale thickness (e.g., ≦10 μm) and a nanoscale to microscale width (e.g., a width of hundreds of nanometers to hundreds of micrometers). Although not including the outermost thermocouple, each thermocouple of the plurality of thermocouples 150 can be disposed within an outer thermocouple, thereby forming the plurality of nested thermocouples described above. The two wires 154 forming the longitudinal loop of each thermocouple of the plurality of thermocouples 150 terminate distally, e.g., with overlapping distal ends at a hot junction 156 within or on the surface of the catheter tube 110. The hot junction 156 is specifically paired with a proximate lactate sensor of the plurality of lactate sensors 124. The two leads 154 terminate distally at a cold junction (not shown) on a printed circuit board assembly 158 of the catheter hub 108. In particular, the thermocouple conductors of the two leads 154 may be differently doped conductive polymers, such as a p-type conductive polymer and an n-type conductive polymer, with relatively high electrical conductivity (e.g., several S / cm) and relatively low thermal conductivity (e.g., several W / [m·K]). Such conductive polymers may be PEDOT:Cl and polyaniline (PANI), respectively.

[0066] Figure 5 shows a cutaway view of the catheter hub 108 of the sensing catheter 104, including a proximal portion of the leads 154 disposed in or on the outer surface of the catheter hub 108, according to some embodiments. Figure 6 shows a detailed view of the catheter tube 110, including a distal portion of the leads 154 disposed in or on the outer luminal surface of the catheter tube 110, according to some embodiments.

[0067] As shown, the two electrical leads 154 may have proximal portions located in or on the outer surface of the catheter hub 108. Furthermore, the proximal portions of the two electrical leads 154 may extend from the outer surface of the catheter hub 108, around the distal surface of the catheter hub 108, and into the bore 114 of the catheter hub 108 to form an electrical junction. The two electrical leads 154 may also have distal portions located in or on the luminal surface of the catheter tube 110. The proximal portions of the two electrical leads 154 in the hub bore 114 form an electrical junction with the distal portions of the two electrical leads 154 in or on the luminal surface of the catheter tube 110 when the proximal end portion of the catheter tube 110 is inserted into the bore 114 of the catheter hub 108. Figure 5 illustrates the formation of an electrical junction as the proximal end portion of the catheter tube 110 is inserted into the bore 114 of the catheter hub 108.

[0068] 2A, 2B, 3A, and 3B, the multiple strain sensors 128 can be disposed within or on the surface of the catheter tube 110 along its initial length. Each strain sensor of the multiple strain sensors 128 is independently electronically addressed by a corresponding strain sensor electrical lead 160 leading thereto. This allows the strain sensing capability of the sensing catheter 104 to be maintained despite cutting off any one or more of the multiple strain sensors 128 along the distal length of the catheter tube 110 when cutting the catheter tube 110 from the initial length to the working length. In particular, the multiple strain sensors 128 and the multiple temperature sensors 126 are each paired along the initial length of the catheter tube 110. This allows local strain measurements to correct for temperature measurement uncertainties due to strain-induced non-uniformity in any one of the multiple temperature sensors 126. Additionally or alternatively, adverse events, such as occlusion or extravasation of a blood vessel, can be detected as local strain measurements at adjacent strain sensors of the multiple strain sensors 128.

[0069] Each strain sensor of the plurality of strain sensors 128 may include a patterned strain-sensitive element 162 (e.g., a serpentine structure up to several millimeters long and ≦100 μm wide) of a strain sensor conductor formed in or on the surface of the catheter tube 110, having a length along the length of the catheter tube 110. The patterned strain-sensitive element 162 is specifically paired with the temperature-sensitive element 152 of a nearby RTD of the plurality of RTDs 148 or the hot junction 156 of a nearby thermocouple of the plurality of thermocouples 150. This allows any change in electrical resistance due to tension, which increases the resistance, or compression, which decreases the resistance, across the patterned strain-sensitive element 162 induced by bending the catheter tube 110 to be measured. In particular, the strain sensor conductor is nanoscale-structured silver or gold, optionally matching that of the RTD conductor.

[0070] method The methods include methods of using the sensing catheter 104 and methods of the system 100 or the sensing catheter 104 itself. For example, the methods of using the sensing catheter 104 may include one or more steps selected from the steps of establishing a puncture path, advancing an access guidewire, withdrawing an introducer needle, cutting, advancing a first catheter, exchanging a guidewire, advancing a second catheter, withdrawing a steering guidewire, connecting an electrical connector, and reading sensor data. In particular, the methods described above are for a sensing catheter 104 configured as a PICC. However, the methods may be adapted as needed for a CVC, a midline catheter, a PIVC, etc.

[0071] The puncture pathway establishing step may include establishing a puncture pathway from the patient's skin area to the vascular cavity with an introducer needle. The access guidewire advancing step may include advancing a distal portion of the access guidewire through the introducer needle and into the vessel lumen until access to the vessel lumen is secured by the access guidewire.

[0072] The introducer needle withdrawal step may include withdrawing the introducer needle from the vessel lumen over the access guidewire, leaving the access guidewire in place within the vessel lumen.

[0073] The trimming step may include trimming a distal length of the catheter tube 110 from its initial length to reduce the catheter tube 110 to a working length. Trimming the distal length of the catheter tube 110 may also trim one or more sensors disposed in or on the surface of the catheter tube 110. However, as described above, the one or more sensors possibly trimmed along with the distal length of the catheter tube 110 are individually electronically addressed, thereby maintaining the sensing capability of the sensing catheter 104 despite their possibly being trimmed along with the distal length of the catheter tube 110. In particular, the one or more sensors possibly trimmed along with the distal length of the catheter tube 110 may, in some embodiments, be any of a synergistic combination of multiple lactate sensors 124, multiple temperature sensors 126, and multiple strain sensors 128. However, the sensing catheter 104 may have any of several different configurations with respect to its one or more sensors as described above, any of which may be included by this method.

[0074] The first catheter advancement step may include advancing a distal portion of the catheter tube 110 over the access guidewire and into the vessel lumen until access to the vessel lumen is secured by the catheter tube 110 .

[0075] The guidewire exchange step may include combining an access guidewire withdrawal step and a steering guidewire advancement step to exchange the access guidewire for a steering guidewire. The access guidewire withdrawal step may include withdrawing the access guidewire from the vascular lumen through the lumen 117 of the sensing catheter 104 in which the access guidewire is disposed while maintaining the catheter tube 110 in place within the vascular lumen. The steering guidewire advancement step may include advancing the steering guidewire through the lumen 117 of the sensing catheter 104 into the vascular lumen until a distal portion of the steering guidewire is at a desired location in the patient, such as the lower third of the patient's superior vena cava (SVC).

[0076] The second catheter advancement step may include advancing the catheter tube 110 further into the vascular lumen over the steering guidewire until the catheter tip 118 is advanced to the desired location within the patient's body (e.g., the lower third of the SVC).

[0077] The operating guidewire withdrawal step may include withdrawing the operating guidewire from the vascular cavity through the lumen 117 of the sensing catheter 104 in which the operating guidewire is disposed, while holding the catheter tube 110 in place at the desired location within the patient's body.

[0078] The electrical connector connecting step may include connecting the proximal end electrical connector 122 of the sensing catheter 104 to the console 102 to read sensor data from a display screen 106 associated with the console 102. As described above, the proximal electrical connector 122 connects the console 102 to the sensor electronics of the sensing catheter 104 and is configured to relay electrical signals to the sensing catheter 104, relay electrical signals from the sensing catheter 104, or both.

[0079] The sensor data reading step may include reading sensor data from one or more sensors to determine the patient's instantaneous state. Such sensor data may be displayed on a display screen 106 associated with the console 102. The clinician then determines the patient's instantaneous state from the sensor data in accordance with the foregoing, although in some embodiments, the console 102 may also automatically determine the patient's instantaneous state and display it for the clinician on the display screen 106.

[0080] Some specific embodiments have been disclosed herein, and while those specific embodiments have been disclosed in some detail, those specific embodiments are not intended to limit the scope of the concepts provided herein. Further adaptations or modifications may become apparent to those skilled in the art, and the broader aspects encompass those adaptations or modifications as well. Thus, departures from the specific embodiments disclosed herein may be made without departing from the scope of the concepts provided herein.

Claims

1. A temperature sensing catheter that is cut to length, A catheter hub; a catheter tube having a proximal end portion adapted to be inserted into a bore in the proximal portion of the catheter hub; a plurality of temperature sensors disposed in or on the surface of the catheter tube along an initial length of the catheter tube, each temperature sensor of the plurality of temperature sensors being independently electronically addressed by a corresponding temperature sensor electrical lead to the temperature sensor, such that when the catheter tube is cut from the initial length to a working length, any one or more of the plurality of temperature sensors is cut off along with a distal length of the catheter tube, yet the temperature sensing capability of the sensing catheter is maintained; one or more extension legs, each extension leg of the one or more extension legs having a distal end portion that is inserted into a proximal portion of the catheter hub; A sensing catheter comprising:

2. The sensing catheter of claim 1 , wherein the plurality of temperature sensors are a plurality of nested thermocouples.

3. 3. The sensing catheter of claim 2, wherein each thermocouple of the plurality of thermocouples comprises a longitudinal loop formed between two wires of different thermocouple conductors having distal portions disposed within or on the surface of the catheter tube, the two wires terminating distally at a thermal junction within or on the surface of the catheter tube.

4. 4. The sensing catheter of claim 3, wherein the two conductors have proximal portions disposed in or on an outer surface of the catheter hub, and the two conductors terminate proximally at a cold junction on a printed circuit board assembly of the catheter hub.

5. 5. The sensing catheter of claim 4, wherein the proximal portions of the two conductors extend from the outer surface of the catheter hub into the bore of the catheter hub, and the proximal portions of the two conductors within the bore of the hub form electrical junctions with the distal portions of the two conductors where the proximal end portion of the catheter tube is inserted into the bore of the catheter hub.

6. The sensing catheter of claim 3 , wherein the two-wire thermocouple conductor is a conductive polymer.

7. The sensing catheter of claim 1 , wherein the plurality of temperature sensors are a plurality of resistance temperature detectors (RTDs).

8. 8. The sensing catheter of claim 7, wherein each RTD of the plurality of RTDs includes a temperature sensing element of an RTD conductor formed in or on the surface of the catheter tube with a known temperature vs. resistance relationship, thereby enabling measured electrical resistance across the temperature sensing element to be converted to temperature.

9. The sensing catheter of claim 7 , wherein the RTD conductor is nanoscale structured silver or gold.

10. 10. The sensing catheter of claim 1, further comprising a plurality of strain sensors disposed in or on the surface of the catheter tube along an initial length of the catheter tube, each strain sensor of the plurality of strain sensors being independently electronically addressed by a corresponding strain sensor electrical lead leading to the strain sensor, such that when the catheter tube is cut from the initial length to a working length, the strain sensing capability of the sensing catheter is maintained despite cutting off any one or more of the plurality of strain sensors along with the distal length of the catheter tube.

11. 11. The sensing catheter of claim 10, wherein the plurality of strain sensors and the plurality of temperature sensors are paired along the initial length of the catheter tube such that temperature measurement uncertainties due to strain-induced non-uniformities in any of the plurality of temperature sensors can be corrected by local strain measurements.

12. 11. The sensing catheter of claim 10, wherein each strain sensor of the plurality of strain sensors comprises a patterned strain sensitive element of a strain sensor conductor formed in or on the surface of the catheter tube having a length along the length of the catheter tube, thereby being able to measure any change in electrical resistance due to tension, which increases resistance, or compression, which decreases resistance, across the patterned strain sensitive element induced by bending of the catheter tube.

13. The sensing catheter of claim 12 , wherein the strain sensor conductor is nanoscale structured silver or gold.

14. The sensing catheter of claim 1 , wherein the surface of the catheter tube independently comprises an endoluminal surface or an endoluminal surface of the catheter tube.

15. 15. The sensing catheter of any one of claims 1 to 14, further comprising an electrical connector configured to connect the sensor electronics of the sensing catheter to a console to relay electrical signals to the sensing catheter, relay electrical signals from the sensing catheter, or both.

16. The sensing catheter of claim 1 , wherein the sensing catheter is a central venous catheter (CVC), a peripherally inserted central catheter (PICC), a midline catheter, or a peripheral intravenous catheter (PIVC).

17. A lactate sensing catheter that is cut to length, A catheter hub; a catheter tube having a proximal end portion adapted to be inserted into a bore in the proximal portion of the catheter hub; a plurality of lactate sensors disposed in or on the surface of the catheter tube along an initial length of the catheter tube, each lactate sensor of the plurality of lactate sensors being independently electronically addressed with a corresponding lactate sensor electrical lead leading to the lactate sensor, such that when the catheter tube is cut from the initial length to a working length, any one or more lactate sensors of the plurality of lactate sensors are cut off along with a distal length of the catheter tube, yet the lactate sensing capability of the sensing catheter is maintained; one or more extension legs, each extension leg of the one or more extension legs having a distal end portion that is inserted into a proximal portion of the catheter hub; A sensing catheter comprising:

18. 18. The sensing catheter of claim 17, wherein each lactate sensor of the plurality of lactate sensors comprises either a three-electrode sensor or a two-electrode sensor, the three-electrode sensor comprising a working electrode, a reference electrode, and a counter electrode, and the two-electrode sensor comprising the working electrode and the reference electrode.

19. 19. The sensing catheter of claim 18, wherein each lactate sensor of the plurality of lactate sensors comprises a two-electrode sensor covered with an anti-fouling membrane, the working electrode comprises a layered working electrode structure having a metal layer underneath a conductive polymer layer having an immobilized enzyme therein or thereon, and the reference electrode comprises a layered reference electrode structure having a metal layer that is the same as or different from the working electrode underneath a metal salt layer.

20. 20. The sensing catheter of any one of claims 17 to 19, further comprising a plurality of temperature sensors disposed in or on the surface of the catheter tube along an initial length of the catheter tube, each temperature sensor of the plurality of temperature sensors being independently electronically addressed by a corresponding temperature sensor electrical lead leading to the temperature sensor, such that when the catheter tube is cut from the initial length to a working length, any one or more of the plurality of temperature sensors is cut off along with the distal length of the catheter tube, yet the temperature sensing capability of the sensing catheter is maintained.

21. 21. The sensing catheter of claim 20, wherein the plurality of temperature sensors and the plurality of lactate sensors are paired along the initial length of the catheter tube such that enzyme activity, and therefore lactate concentration, associated with any lactate sensor of the plurality of lactate sensors can be normalized by at least local temperature compensation.

22. The sensing catheter of claim 21 , wherein the plurality of temperature sensors are a plurality of nested thermocouples.

23. 23. The sensing catheter of claim 22, wherein each thermocouple of the plurality of thermocouples comprises a longitudinal loop formed between two wires of different thermocouple conductors having distal portions disposed in or on the surface of the catheter tube, the two wires terminating distally at hot junctions in or on the surface of the catheter tube.

24. 24. The sensing catheter of claim 23, wherein the two conductors have proximal portions disposed in or on an outer surface of the catheter hub, and the two conductors terminate proximally at a cold junction on a printed circuit board assembly of the catheter hub.

25. 25. The sensing catheter of claim 24, wherein proximal portions of the two electrical leads extend from an outer surface of the catheter hub into the bore of the catheter hub, and the proximal portions of the two electrical leads within the bore of the hub form electrical junctions with the distal portions of the two electrical leads where the proximal end portion of the catheter tube is inserted into the bore of the catheter hub.

26. 26. The sensing catheter of any one of claims 22 to 25, wherein the two-wire thermocouple conductor is a conductive polymer.

27. 27. The sensing catheter of any one of claims 17 to 26, wherein the plurality of temperature sensors are a plurality of resistance temperature detectors (RTDs).

28. 28. The sensing catheter of claim 27, wherein each RTD of the plurality of RTDs includes a temperature sensing element of an RTD conductor formed in or on the surface of the catheter tube with a known temperature vs. resistance relationship, thereby enabling any electrical resistance measured across the temperature sensing element to be converted to a temperature.

29. 28. The sensing catheter of claim 27, wherein the RTD conductor is nanoscale structured silver or gold.

30. 30. The sensing catheter of any one of claims 17 to 29, comprising a plurality of strain sensors disposed in or on the surface of the catheter tube along the initial length of the catheter tube, each strain sensor of the plurality of strain sensors being independently electronically addressed by a corresponding strain sensor electrical lead leading to the strain sensor, such that when the catheter tube is cut from the initial length to the working length, any one or more of the plurality of strain sensors is cut off along with the distal length of the catheter tube, thereby maintaining the strain sensing capability of the sensing catheter.

31. 31. The sensing catheter of claim 30, wherein the plurality of strain sensors and the plurality of temperature sensors are paired along the initial length of the catheter tube such that temperature measurement uncertainties due to strain-induced non-uniformities in any of the plurality of temperature sensors can be corrected by local strain measurements.

32. 31. The sensing catheter of claim 30, wherein each strain sensor of the plurality of strain sensors comprises a patterned strain sensitive element of a strain sensor conductor formed in or on the surface of the catheter tube having a length along the length of the catheter tube, thereby being able to measure any change in electrical resistance due to tension, which increases resistance, or compression, which decreases resistance, across the patterned strain sensitive element induced by bending of the catheter tube.

33. 33. The sensing catheter of claim 32, wherein the strain sensor conductor is nanoscale structured silver or gold.

34. 34. The sensing catheter of any one of claims 17 to 33, wherein the surface of the catheter tube independently comprises an endoluminal surface or an endoluminal surface of the catheter tube.

35. 35. The sensing catheter of any one of claims 17 to 34, further comprising an electrical connector configured to connect the sensor electronics of the sensing catheter to a console to relay electrical signals to the sensing catheter, relay electrical signals from the sensing catheter, or both.

36. 36. The sensing catheter of any one of claims 17 to 35, wherein the sensing catheter is a central venous catheter (CVC), a peripherally inserted central catheter (PICC), a midline catheter, or a peripheral intravenous catheter (PIVC).

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