Method and device for measuring a component in exhaled breath

Abstract

A device for measuring a component in exhaled breath comprising an inlet for receiving exhaled breath, a buffer chamber. A first fluid conduit is in fluid connection with the inlet and adapted to lead a first portion of the exhaled breath to the buffer chamber. The buffer chamber comprises an outlet for discarding a first part of exhaled breath received from the first fluid conduit and the buffer chamber is configured to buffer a second part of exhaled breath received from the first fluid conduit. The device comprises a second fluid conduit in fluid connection with the inlet and adapted to lead a second portion of the exhaled breath to be discarded, and a sensor for measuring a component in the exhaled breath buffered in the buffer chamber.

1 . A device for measuring a component in exhaled breath comprising;
 an inlet for receiving exhaled breath,   a buffer chamber,   a first fluid conduit in fluid connection with the inlet and adapted to lead a first portion of the exhaled breath to the buffer chamber, which buffer chamber comprises an outlet for discarding a first part of exhaled breath received from the first fluid conduit and wherein the buffer chamber is configured to buffer a second part of exhaled breath received from the first fluid conduit,   a second fluid conduit in fluid connection with the inlet and adapted to lead a second portion of the exhaled breath to be discarded, and   a sensor for measuring a component in the exhaled breath buffered in the buffer chamber.   
     
     
         2 . The device according to  claim 1 , wherein the first fluid conduit has a first flow cross-section area, perpendicular to the direction of the flow in the first fluid conduit, and the second fluid conduit has a second flow cross-section area, perpendicular to the direction of the flow in the second fluid conduit, and wherein the second flow cross-section area is larger than the first flow cross-section area. 
     
     
         3 . The device according to  claim 2 , wherein the first flow cross-section area is at least one of: 0.5 times the area of the second flow cross-section area, and 0.3 times the area of the second flow cross-section area. 
     
     
         4 . The device according to  claim 1 , wherein the buffer chamber comprises a buffer conduit, and wherein the outlet is arranged at a distal portion of the buffer conduit with respect to the inlet or the first fluid conduit. 
     
     
         5 . The device according to  claim 4 , wherein buffer conduit has a cross-sectional dimension, perpendicular to the direction of the flow in the buffer conduit, having a length less than: ⅕ of the length of the buffer conduit, 1/10 of the length of the buffer conduit, 1/20 of the length of the buffer conduit, 1/50 of the length of the buffer conduit, 1/70 of the length of the buffer conduit, or 1/100 of the length of the buffer conduit. 
     
     
         6 . The device according to  claim 4 , wherein the buffer chamber comprises a buffer conduit with at least one meander or S-shape. 
     
     
         7 . The device according to  claim 6 , wherein the corners of the buffer conduit with at least one meander or S-shape have rounded inside corners. 
     
     
         8 . The device according to  claim 1 , comprising an adjustment member. 
     
     
         9 . The device according to  claim 8 , comprising a replaceable adjustment member. 
     
     
         10 . The device according to  claim 8 , wherein the adjustment member is an adjustable bifurcating wall. 
     
     
         11 . The device according to  claim 1 , wherein the buffer chamber further comprises a first check valve, preferably placed at the outlet, such that fluid will be stopped from entering the buffer chamber during inhalation. 
     
     
         12 . The device according to  claim 1 , wherein the device further comprises a second check valve placed in the second fluid conduit such that fluid will be stopped from entering the second fluid conduit during inhalation. 
     
     
         13 . The device according to  claim 1 , wherein the device further comprises a pump adapted to pump exhaled breath from the buffer chamber to the sensor. 
     
     
         14 . The device according to  claim 1 , wherein the component in exhaled breath is the amount of NO. 
     
     
         15 . The device according to  claim 1 , wherein the sensor is an electrochemical sensor. 
     
     
         16 . The device according to  claim 1 , wherein the sensor is a sensor having a response time of more than 5 seconds, or in the range of 5-15 seconds. 
     
     
         17 . A method of measuring the concentration of a component in exhaled breath, comprising the steps of:
 receiving exhaled breath,   leading a first portion of the exhaled breath through a first fluid conduit to a buffer chamber,   leading a second portion of the exhaled breath through a second fluid conduit to be discarded,   from the buffer chamber, discarding a first part of the first portion of the exhaled breath received from the first fluid conduit,   in the buffer chamber, buffering a second part of the first portion of the exhaled breath received from the first fluid conduit, and   measuring the concentration of the component in the exhaled breath buffered in the buffer chamber.   
     
     
         18 . The method according to  claim 17 , comprising adjusting the flow of fluid into the first and second fluid conduits respectively. 
     
     
         19 . The method according to  claim 18 , wherein the device for measuring exhaled breath comprises an adjustment member, and wherein the step of adjusting the flow of fluid comprises adjusting the adjustment member. 
     
     
         20 . The method according to  claim 18 , wherein the device for measuring exhaled breath comprises a replaceable adjustment member, and wherein the step of adjusting the flow of fluid comprises replacing the adjustment member.