1 . this is the only device which measures airway inflammation with a simple home assay , without invasive procedures or expensive and cumbersome testing equipment . 3 . clinical application for individual patients in their own home or in the clinic or hospital setting to test for or monitor status of asthma or other causes of airway inflammation . may be used to predict disease exacerbations , allowing time for successful early intervention . 4 . clinical applicability in the setting of mechanically ventilated patient to easily monitor airway inflammation . 5 . clinical applicability for measuring airway inflammation in many children too young to cooperate with standard pulmonary function testing , but who can cooperate with tidal breathing through a tube . similar potential in patients with neuromuscular disease in whom standard tests are uninterpretable . the device can be made with easily available materials . the cooling substance in the condensing chamber can be water , or a viscous substance with a high specific heat . the device can also be made , as described above , without refrigerant , utilizing a gas / membrane or gas / aqueous reaction compartment . referring now to fig1 mouthpiece 1 is formed as an integral element with low resistance one - way valve 2 allowing inspiration of air into the device of the invention resulting from inhalation through it by the user . low resistance one - way valve 2 optionally contains potassium permanganate and a charcoal filter to remove ambient nitrogen oxides . mouthpiece 1 and low resistance one - way valve 2 are further integral with low resistance one - way valve 3 to direct all expired gas from the user into the remaining elements of the device . integral with and downstream of low resistance one - way valve 3 is low resistance filter 4 , containing elements which removes all particulates greater than 0 . 03 μm in diameter . connected downstream to low resistance filter 4 is condensing chamber 5 which consists of either a single , long inert plastic tube of sufficient diameter to be of low resistance to air expired into the device , or a bundle of shorter , parallel , inert plastic tubes of sufficient number to provide minimal resistance to airflow . condensing chamber 5 is in continuity with , i . e ., receives air arising from filter 4 . coolant chamber or jacket 6 contains an aqueous solution of sufficient osmolality to cause freezing point depression to just above the minimum temperature of the average household freezer , e . g ., in a range of ± 15 ° f ., preferably below 0 ° f . condensing chamber 5 is completely sealed from exposure to coolant chamber 6 . essentially coolant chamber 6 coaxially surrounds condensing chamber 5 so as to control the temperature within condensing chamber 5 . condensing chamber 5 is continuous with a conduit that divides to condensate delivery conduit 7 and exhaust port 8 . a reagent impregnated mesh , such as filter paper , can optionally be situated in condensate delivery conduit 7 for reagent combination with condensate prior to their arrival in sample analysis assembly 9 . exhaust port 8 comprises a one - way , low - resistance valve through which air , in which the condensate has been analyzed , is expelled from the device of the invention . sample analysis assembly 9 is connected to the outlet of condensing chamber 5 through condensate delivery conduit 7 and is described in detail with reference to fig2 a . analyzer 10 which is not a component of the disposable device of the invention , includes a wavelength - filtered light source and photometer bulb , for measuring the specific absorbance of reacted reagent in sample analysis assembly 9 , and a computer both for calculating and displaying the corresponding nitrogen oxide content of the sample in sample analysis assembly 9 and for calibrating the absorbance / concentration relationship based on standard samples is shown as an association of conventional elements in essentially block form . elements 1 through 9 of the device of the present invention form a disposable unit which is stored under refrigeration , preferably frozen , until used . in contrast , analyzer 10 is not disposable and is maintained at room temperature . the disposable unit comprising elements 1 - 9 is removed from frozen storage and placed as a unit in connecting housing 11 , which is attached to analyzer 10 in such a way that sample analysis assembly 9 fits snugly into connecting housing 11 . connecting housing 11 serves to hold the disposable and non - disposable units together at the appropriate orientation , and to prevent the subject user &# 39 ; s hand from becoming affected by the cold of the disposable device while holding the apparatus during gas sampling . sample analysis assembly 9 is surrounded by a thermostatically controlled heating coil 12 attached to connecting housing 11 and analyzer 10 which brings the sample and test reagents to 25 ° c . heating coil 12 is part of the non - disposable unit . referring now to fig2 a , illustrated in hatched line is the outlet of condensate delivery conduit 7 , which is in enclosed fluid communication with sample analysis assembly 9 . sample analysis 9 comprises contiguous with a round , hard - plastic clear or translucent analysis chamber 13 , a pliable reagent chamber 14 and pliable element 15 . condensate delivery conduit 7 and sample analysis assembly 9 are brought into juxtaposition and are connected by pliable element 15 , which is a soft - plastic component that extends beyond the diameter of condensate delivery conduit 7 . at the bottom of analysis chamber 13 is an opening 16 in which is positioned a fluid - permeable membrane or a thin , plastic rupturable membrane 18 . reagent ( s ) for colorimetric nitrogen oxide salt analysis could be a diazo reagent , or such a reagent in conjunction with nitrate reductase and appropriate cofactors to enable both nitrite and nitrate to be measured simultaneously . other reactions , such as reduction of nitrite and nitrate to nitric oxide in vanadium chloride , followed by reaction with oxyhemoglobin to achieve a colorimetric shift in the soret band , and including heterolytic cleavage of s — no bonds with mercuric chloride followed by diazo analysis could also be employed . when exhaled , the condensate of exhaled air passed into condensate delivery conduit 7 and then into analysis chamber 13 . thereafter , the user squeezes pliable element 15 , using pincer 17 ( shown in fig2 b ). when pincer 17 is closed against pliable element 15 , this causes the volume of reagent chamber 14 to decrease such that reagent therein is forced upwardly through the opening 16 and permeable or rupturable membrane into analysis chamber 13 to combine and react with the condensate . thereafter , the reaction product of this chemical reaction is analyzed by colorimetry using the non - disposable colorimeter which passes a beam of light through a fixed path of analysis chamber 13 . the distal end of the condensing chamber tube ( s ) 5 is attached to a collecting apparatus comprising condensate delivery conduit 7 which utilized gravity to trap condensed fluid . at the bottom of this trap is flexion element 15 and the clear plastic analysis chamber 13 in which the sample is sequentially warmed , sealed , reacted with colorimetric reagents from reagent chamber 14 and analyzed spectrophotometrically by the non - disposable colorimeter through the analysis chamber 13 . the patient breathes comfortably in and out through the mouthpiece 1 . lung fluid vapor collects on the inner surface of the inner tube ( s ) 5 of the condensing apparatus starting immediately . gravity carries the larger droplets down the tube ( s ) 5 , these droplets recruiting other small droplets on their trip to the condensate delivery conduit 7 distally . alternatively , after a fixed period of tidal breathing , the condensed fluid can be expressed down the inner tube 5 with a device similar to a syringe plunger . aqueous phase nitrite and nitrate can be measured by standard colorimetric assays , and can be reasonably quantified by simple tests performed by patients in their homes . 1 . attachment of an assembly distal to the inspiratory portion which would contain a fiber paper through which the saliva free exhalate is channelled . the filter paper would be impregnated with reagents which react with nitrogen oxides and subsequently change color . a patient could breathe through the filter paper for a given period of time and the degree of color change could be measured against a chart or with a small colorimetric device . 2 . direct attachment to the distal end of the condensing chamber of a filter paper impregnated with dried reagents which will react with the aqueous phase nitrogen oxides to yield a change in color of the paper which can easily be measured in a similar fashion to modification # 1 above . 3 . direct attachment of a chamber containing liquid reagents through which the exhalate is bubbled , allowing exhaled nitrogen oxides to directly react with reagents , producing a measurable color change . 4 . attachment of a dehumidifying chamber to the inspiratory portion to eliminate environmental liquid phase nitrogen oxides . recent insights regarding the use of expired nitric oxide ( no .) concentration measurement as an index of airway inflammation cannot be applied to children too young to perform vital capacity ( vc ) maneuvers . we have therefore developed assays which require only tidal breathing . sequential colorimetric measurements were made during quiet breathing by reacting dried air expirate ( dae ) with griess reagent under acid conditions . tidal expired gas no . production rates ( v no . ) were also measured by chemiluminescence over 5 minutes using a 765 liter sealed plethysmograph . eight control subjects and 6 patients with asthma and cystic fibrosis ( cf ) were studied . dae no — was detected in all normal subject samples with mean (± sd ) accumulation curve slope = 40 ± 17 nmoles / liter / breath ( p & lt ; 0 . 05 compared with air controls ). by comparison , the mean [ dissolved nitrogen oxides ( no x )] collected in a precipitation tube ( pt ) (− 80 ° c .) from size - filtered lung water produced by normal subjects during quiet breathing was 0 . 8 ± 0 . 1 μm . tidal v no / body surface area ( specific v no . [ v no . sp ]) was 0 . 21 ± 0 . 043 μl / min / m 2 in normal subjects . consistent with previous reports based on vc measurements , patients with asthma had higher v no . sp ( 0 . 31 ± 0 . 014 μl / min / m 2 , p & lt ; 0 . 01 ) and pt no x ( 16 ± 4 . 0 μm , p & lt ; 0 . 005 ). further , patients with cf also had high v no . sp ( 0 . 34 ± 0 . 84 μl / m 2 / min , p & lt ; 0 . 005 ). we report for the first time 1 ) the detection of no — in expired air through the use of colorimetric assays ; 2 ) the effort - independent detection of v no — ; and 3 ) increases in these tidal breath concentrations in patients with asthma and cf . we speculate that tidal - breathing based techniques will have clinical utility both as measures of airway inflammation applicable to home use and as effort - independent measures of airway disease in the pediatric pulmonary function laboratory . asthma is an inflammatory disease which leads to airway obstruction . current tests of disease severity are based on measures of obstruction , alterations of which are late findings in asthma exacerbations . recent studies reveal that expression of inducible nitric oxide synthase ( inos ) is increased in the airway epithelial and inflammatory cells of patients with asthma . the activity of inos is known to be reflected in high concentrations of nitric oxide ( no .) gas measured in the expired air of asthmatic subjects . we studied other aqueous phase no x in asthmatic aspirate in an effort to develop a simple test for airway inflammation applicable to home use . no history of acute , chronic , or recurrent cardiopulmonary , determatologic , gastrointestinal , or neurologic disease . saliva free , 0 . 2 micron particle size - filtered expired vapor was obtained from subjects breathing quietly through a condensing apparatus . nitrate ( no 3 —) was assayed by chemiluminescence after reduction in vanadium chloride . mean no x concentrations were compared using unpaired t - testing . results are presented as mean , ± standard error . p values of & lt ; 0 . 05 were considered significant . as shown in fig3 nitrite concentrations were significantly higher in asthmatic subjects ( 1 . 877 μm ± 0 . 36 ) than in controls ( 0 . 902 μm ± 0 . 08 ) ( p & lt ; 0 . 01 ). as shown in fig4 nitrate concentrations were likewise significantly elevated in asthmatic subjects ( 9 . 48 μm ± 1 . 25 ) relative to controls ( 5 . 27 μm ± 0 . 51 ) ( p & lt ; 0 . 01 ). tests of airway obstruction , such as the peak flow meter , are currently the primary modality for objectively assessing severity of inflammatory airway disease . these tests have several limitations , including being effort - dependent , and thus are not suitable for many children and neuro - muscularly handicapped individuals . they also poorly reflect the degree of underlying inflammation . utilizing recent insights regarding the biochemistry of higher oxides of nitrogen , we have developed a simple , non - invasive assay for airway inflammation . tests such as this could be performed at home , and may prove to be useful in longitudinal evaluation and management of asthma , including dosing of anti - inflammatory medication . aqueous phase nitrogen oxides , measured in condensed exhalate , are significantly elevated in asthmatic patients , and can be used to distinguish between normal and inflamed airways .
disclosed is a device for determination of the content of higher oxides of nitrogen in exhaled breath condensate which comprises a conduit having an exhalate condensing portion with an inlet and an outlet ; a coolant jacket coaxially surrounding said exhalate condensing portion ; a gas release port ; and , in enclosed fluid communication with said conduit exhalate condensing portion outlet , a sample assay assembly comprising a translucent analysis chamber attached to the outlet to receive condensate fluid and having a reagent entry port , a reagent chamber in enclosed fluid communication with the reagent entry port and a pliable element connecting the outlet and the analysis chamber and forming a portion of the reagent chamber such that flexion of the pliable element closes communication between the outlet and the analysis chamber and contracts the reagent chamber so as to deliver to the analysis chamber controlled amounts of condensate and reagent . the device is disposable and inexpensive , and is used to collect human exhalate for colorimetric assay of liquid and gas phase nitrogen oxides to assist in evaluation of airway inflammation .