Fluid analysis system

Abstract

Systems and method are disclosed for determining a concentration of an analyte in a fluid (e.g., blood). The system can draw blood from a patient and deliver the blood to a sample cell. A particular component of the fluid (e.g., plasma) may be separated and/or positioned such that the concentration of the analyte is measured in the particular component of the fluid (e.g., plasma). The sample cell can include a sample container that has two window pieces. The system can have a fluid passage having a tip configured to mate with a multi-lumen catheter without leaking. The multi-lumen catheter can have proximal and distal ports. A fluid pressure system can be configured to periodically draw fluid from vasculature through a proximal intravascular opening and the proximal port while maintaining a low pressure and/or flow rate to thereby reduce risk of reversing the fluid flow in a vessel and drawing infusates upstream into another intravascular opening.

1 .- 18 . (canceled) 
     
     
         19 . A system comprising:
 an analyte measurement system configured to measure the concentration of an analyte in at least a portion of a fluid sample;   a fluid handling system configured to receive the fluid sample and to deliver at least a portion of the fluid sample to the analyte measurement system;   a fluid infusion system configured to infuse fluid through a fluid infusion line to a distal intravascular opening into a vessel having a flow of bodily fluid in a patient;   a fluid draw line configured to draw bodily fluid from the vessel through a proximal intravascular opening, wherein proximal intravascular opening is upstream from the distal intravascular opening on the vessel;   an accommodating medical connector that couples the fluid draw line to the fluid handling system, the connector comprising:
 a housing having a first side, a second side, and an internal volume, wherein a fluid line of the fluid handling system extends through the first side of the housing and into the internal volume, wherein the second side of the housing is removably coupled to a corresponding connector that is coupled to the fluid draw line; 
 a movable tube having a first portion disposed inside the internal volume of the housing and a second portion that extends past the second side of the housing and into the corresponding connector, wherein the movable tube is movable to adjust the amount of the movable tube that is inside the internal volume of the housing and to adjust how far the movable tube extends past the second side of the housing; 
 a coupler inside the internal volume of the housing, wherein the coupler couples the fluid line to the movable tube so that movement of the movable tube causes corresponding movement of the fluid line relative to the housing, and wherein the coupler provides a fluid path between the fluid line and the movable tube; and 
 a biasing member disposed inside the internal volume of the housing, wherein the biasing member biases the movable tube toward the corresponding connector; and 
   a fluid pressure system configured to periodically draw bodily fluid from the vessel through the proximal intravascular opening, through the fluid draw line, through the connector, and to the fluid handling system, wherein the fluid pressure system is configured to draw the bodily fluid through the proximal intravascular opening at a sufficiently low pressure and/or flow rate to impede reversal of the flow of the bodily fluid in the vessel.   
     
     
         20 . The system of  claim 19 , wherein the fluid pressure system is configured to draw the bodily fluid through the proximal intravascular opening at a first flow rate when the fluid infusion system is infusing fluid through the distal intravascular opening, wherein the fluid pressure system is configured to draw the bodily fluid through the proximal intravascular opening at a second flow rate when the fluid infusion system is not infusing fluid through the distal intravascular opening, and wherein the first flow rate is lower than the second flow rate. 
     
     
         21 . The system of  claim 19 , wherein the fluid pressure system is configured to draw the bodily fluid at a flow rate between approximately 1 mL per minute and approximately 10 mL per minute. 
     
     
         22 . The system of  claim 19 , wherein the fluid pressure system is configured to draw the bodily fluid at a pressure between approximately 1 psi and approximately 10 psi. 
     
     
         23 . The system of  claim 19 , wherein the fluid pressure system is configured to draw the bodily fluid at a sufficiently low pressure and/or flow rate that the amount of the fluid infused through the distal intravascular opening is less than 10 parts per million. 
     
     
         24 . The system of  claim 19 , wherein the fluid pressure system comprises a syringe pump. 
     
     
         25 . The system of  claim 19 , wherein the movable tube has a tip at one end that engages the fluid draw line. 
     
     
         26 . The system of  claim 25 , wherein the tip of the movable tube has a square cross-sectional shape. 
     
     
         27 . The system of  claim 25 , wherein the tip of the movable tube is tapered. 
     
     
         28 . The system of  claim 25 , wherein the tip of the movable tube is beveled. 
     
     
         29 . The system of  claim 25 , wherein the tip of the movable tube is stiffer than the fluid draw line. 
     
     
         30 . The system of  claim 19 , wherein the tip of the movable tube comprises polyimide. 
     
     
         31 . The system of  claim 19 , wherein the accommodating medical connector is configured to maintain substantially uniform velocity of the bodily fluid across the accommodating connector. 
     
     
         32 . The system of  claim 19 , wherein an inner diameter of the movable tube of the accommodating medical connector is approximately the same as an inner diameter of the fluid draw line. 
     
     
         33 . The system of  claim 19 , wherein the accommodating medical connector is configured to restrict fluid flowing through the accommodating medical connector to the fluid draw line, the coupler, and the movable tube. 
     
     
         34 . The system of  claim 19 , wherein the accommodating medical connector is configured so that fluid flowing through the accommodating medical connector does not contact the inside of the housing. 
     
     
         35 . The system of  claim 19 , wherein the biasing member comprises a spring. 
     
     
         36 . The system of  claim 35 , wherein the spring is compressed between a interior surface of the housing and the coupler. 
     
     
         37 . The system of  claim 19 , wherein the accommodating medical connector provides a linear flow path through the accommodating medical connector. 
     
     
         38 . The system of  claim 19 , wherein the analyte measurement system comprises an optical measurement system, and wherein the system includes a cuvette that comprises:
 a first window piece that is configured to be transparent to light emitted by the optical measurement system;   a second window piece that is configured to be transparent to the light emitted by the optical measurement system;   a spacer positioned between the first window piece and the second window piece to provide a gap between the first window piece and the second window piece, wherein the gap forms a sample chamber between the first window piece and the second window piece, and wherein the sample chamber is configured to receive the at least a portion of the fluid sample from the fluid handling system;   a first clamping element; and   a second clamping element, wherein the first and second clamping elements are positioned on opposite outer sides of the first and second window pieces, wherein the first and second clamping elements are secured to each other to provide support to the first and second window pieces, wherein the first and second clamping elements are configured to permit the light emitted by the optical measurement system to pass through the sample chamber of the cuvette.