Devices, systems, and methods for aiding in the detection of a physiological abnormality

Abstract

A method for aiding in the diagnosis of a physiological abnormality resulting in detectable, measurable variations in contents of breathed air. The system includes a handheld unit defining an airway, wherein the airway includes a plurality of sensors adapted to measure a plurality of parameters related to the presence of a physiological abnormality. The system further includes a control unit remotely connected to the handheld unit. The control unit includes a controller adapted to receive input signals from the handheld unit and remit output signals in response thereto. The output signals are usable by a user in determining the presence or absence of a physiological abnormality. The control unit further also can include a display adapted to display the output signals to a user thereby easing the determination of the physiological abnormality. The system further includes a mouthpiece selectively connectable to the handheld unit. The mouthpiece can include a filter adapted to substantially prohibit the passage of germs into the airway of the handheld unit.

What is claimed is: 
     
         1 . A method for identifying the presence of a respiratory dysfunction, the method comprising:
 measuring a concentration of produced carbon dioxide in a volume of exhaled air;   measuring a concentration of unconsumed oxygen in the volume of exhaled air;   calculating a carbox ratio wherein the carbox ratio represents the concentration of produced carbon dioxide in relation to the concentration of unconsumed oxygen;   comparing the calculated carbox ratio to a first known value indicating the presence of a respiratory dysfunction and a second known value indicating the absence of a respiratory dysfunction, wherein the calculated carbox ratio may fall between the first known value and second known value;   applying one or more normalization factors to any carbox ratio falling between the first known value and second known value to derive a normalized carbox ratio, wherein the one or more normalization factors are applicable independently or in combination with each other; and   determining a presence or absence of a respiratory dysfunction by comparing the normalized carbox ratio to a threshold value that signals the presence or absence of pulmonary embolism.   
     
     
         2 . The method of  claim 1 , wherein the normalization factor is a measured non-gas exchanging portion of the volume of exhaled air. 
     
     
         3 . The method of  claim 1 , wherein the normalized carbox ratio is further normalized by corresponding mean value plethsmography measurements. 
     
     
         4 . The method of  claim 3 , wherein the normalized carbox ratio and mean and/or variability values of plethsmography measurements are simultaneously compared to established threshold values to determine the absence of pulmonary embolism. 
     
     
         5 . The method of  claim 3 , wherein the normalized carbox ratio and mean and/or variability values of plethsmography measurements are simultaneously compared to established threshold values to determine the need for further testing to determine the presence of pulmonary embolism. 
     
     
         6 . The method of  claim 1 , wherein the normalized carbox ratio is further normalized by corresponding mean value plethsmography measurements, wherein the normalized carbox ratio and mean and/or variability values of plethsmography measurements are simultaneously compared to established threshold values to determine the absence of pulmonary embolism or the need for further testing to determine the presence of pulmonary embolism. 
     
     
         7 . The method of  claim 1  further comprising measuring a volume of oxygen consumed in a volume of inhaled air. 
     
     
         8 . The method of  claim 7 , wherein the normalization factor is a respiratory quotient (RQ) representing a ratio of the volume of produced carbon dioxide to the volume of oxygen consumed in the volume of inhaled air. 
     
     
         9 . The method of  claim 8 , wherein the normalization factor is a ratio of RQ to a non-gas exchanging portion of the volume of the volume of exhaled air. 
     
     
         10 . The method of  claim 1 , wherein the normalization factor is a measured total volume of air breathed in during a 1-minute period. 
     
     
         11 . The method of  claim 10 , wherein the normalization factor applies to a carbox ratio normalized by a measured non-gas exchanging portion of the volume of exhaled air. 
     
     
         12 . The method of  claim 11 , wherein the normalization factor is a ratio of the measured total volume of air breathed in during a 1-minute period to a measured volume of oxygen breathed in during the 1-minute period. 
     
     
         13 . The method of  claim 12 , wherein the normalization factor applies to a carbox ratio normalized by a measured non-gas exchanging portion of the volume of exhaled air. 
     
     
         14 . The method of  claim 1 , wherein the normalization factor is the measured total volume of air breathed in during a 1-minute period less a measured non-gas exchanging portion of the volume of exhaled air. 
     
     
         15 . The method of  claim 1 , wherein the carbox ratio is a mean value calculated over a number of measured breaths and the one or more normalization factors are mean values calculated over the number of breaths. 
     
     
         16 . An improved method for identifying the presence or absence of a respiratory dysfunction, the method comprising:
 measuring a concentration of carbon dioxide produced during the duration of an exhaled breath of air;   measuring a concentration of unconsumed oxygen during the duration of an exhaled breath of air;   determining a point of change in a rate of molecular exchange in the volume of exhaled air;   calculating a carbox ratio representing a concentration of carbon dioxide produced at the point of change and concentration of unconsumed oxygen produced at the point of change;   comparing the calculated carbox ratio to a first known value indicating the presence of a respiratory dysfunction and a second known value indicating the absence of a respiratory dysfunction, wherein the calculated carbox ratio may fall between the first known value and second known value;   applying one or more normalization factors to any carbox ratio falling between the first known value and second known value to derive a normalized carbox ratio, wherein the one or more normalization factors are applicable independently or in combination with each other; and   determining the presence or absence of a respiratory dysfunction by comparing the normalized carbox ratio to a threshold value that signals the presence or absence of pulmonary embolism.   
     
     
         17 . An improved method for identifying the presence or absence of a respiratory dysfunction, the method comprising:
 calculating normal lung volume based on a group of physiological factors, wherein the group comprises a patient's gender, height, weight and age;   calculating a ratio of an expected concentration of carbon dioxide in an expected volume of exhaled air to an expected concentration of unconsumed oxygen in the expected volume of exhaled air   measuring actual concentrations of carbon dioxide and unconsumed oxygen produced in a volume of exhaled air;   calculating a carbox ratio representing the actual concentration of carbon dioxide produced relative to the actual concentration of unconsumed oxygen produced in a volume of exhaled air;   comparing a ratio of the measured actual concentrations to the ratio of expected concentrations;   identifying any deviation between the actual and expected ratios; and   diagnosing respiratory dysfunction based on an analysis of this deviation.   
     
     
         18 . The method of  claim 17  further comprising applying one or more normalization factors to the carbox ratio to produce a normalized carbox ratio. 
     
     
         19 . The method of  claim 18  further comprising comparing the normalized carbox ratio to a known threshold value indicative of pulmonary embolism. 
     
     
         20 . The method of  claim 19  further comprising diagnosing a pulmonary embolism based on a combined analysis of the comparison of the normalized carbox ratio to a known threshold value and the comparison of the carbox ratio to the ratio of expected amounts. 
     
     
         21 . The method of  claim 17  further comprising applying one or more normalization factors to the carbox ratio to produce a normalized carbox ratio, comparing the normalized carbox ratio to a known threshold value indicative of pulmonary embolism, and diagnosing a pulmonary embolism based on a combined analysis of the comparison of the normalized carbox ratio to a known threshold value and the comparison of the carbox ratio to the ratio of expected amounts. 
     
     
         22 . An improved method for identifying pulmonary embolism in patients, the method comprising the steps of:
 measuring a D-dimer concentration in a blood sample;   determining whether the measured D-dimer concentration is above a threshold indicative of concern;   performing, in cases when the determining step indicates that the D-dimer concentration is above the threshold, a respiratory test comprising the steps of:
 measuring a concentration of produced carbon dioxide in a volume of exhaled air; 
 measuring a concentration of unconsumed oxygen in the volume of exhaled air; 
 calculating a carbox ratio wherein the carbox ratio represents the concentration of produced carbon dioxide in relation to the concentration of unconsumed oxygen; 
 determining whether the calculated carbox ratio is less than or equal to a carbox ratio threshold; and 
   outputting an indication, in cases when the calculated carbox ratio is less than or equal to the carbox ratio threshold, that a pulmonary embolism is likely.   
     
     
         23 . The method of  claim 22 , wherein the carbox ratio threshold is between 0.25 and 0.30. 
     
     
         24 . The method of  claim 22 , wherein the carbox ratio threshold is 0.28. 
     
     
         25 . The method of  claim 22 , further comprising the step of outputting an indication, in cases when the calculated carbox ratio is above the carbox ratio threshold, that additional diagnostic testing is required. 
     
     
         26 . The method of  claim 25 , wherein the carbox ratio threshold is between 0.25 and 0.30.