Apparatus and method for monitoring the degree of integration between the functions of the heart and the lungs, and the therapeutic success of resuscitative interventions

Abstract

A method, system and apparatus for assessing the coupling between lung perfusion and ventilation in a patient who is mechanically ventilated or who is breathing spontaneously through a conventional artificial airway is provided. Embodiments of the apparatus comprise an adaptor configured to fit between the artificial airway and mechanical ventilator, a measuring chamber in constant fluid communication with the adaptor via one or more measuring chamber sampling ports, and a monitoring unit where data obtained from temperature and relative humidity sensors located in the measuring is calibrated, sampled, logged and analyzed together with anthropometric patient data to display a coupling index Qi and to enable ongoing diagnostic cardio-pulmonary monitoring of a patient by comparing changes in the patient's index during a monitoring interval.

We claim: 
     
         1 . Apparatus for assessment and monitoring of the coupling between lung perfusion and ventilation in a patient who is mechanically ventilated or breathing spontaneously through an artificial airway, the apparatus comprising:
 an adaptor providing a main path for gases inhaled and/or exhaled by the patient;   a measuring chamber in constant fluid communication with the adaptor but out of the main path of the gases inhaled and/or exhaled by the patient through the adaptor, said measuring chamber comprising temperature and relative humidity sensors for measuring the temperature and humidity of the gases inhaled and/or exhaled by the patient; and,   a monitoring unit in fluid and electrical communication with the measuring chamber, the monitoring unit comprising:
 one of a thermocouple and a flow meter; 
 a suction pump for drawing said inhaled and/or exhaled gases from said adaptor and through said thermocouple or flow meter via said measuring chamber; 
 display and data entry means; and 
 a monitoring unit control system, processor and memory for the acquisition, conversion, and storage of data acquired from the temperature and relative humidity sensors, from the thermocouple or flow meter, and from an operator of the system, wherein the monitoring unit is configured, in use, to: 
   a) store patient data values entered by the operator via the data entry means;   b) detect a plurality of breathing phases of the patient by determining an interval between a low and/or high temperature and/or humidity plateaus between individual inhalations and/or exhalations as measured by the temperature and/or relative humidity sensors;   c) obtain and store base heat exchange values from the measured temperature and relative humidity of the inhaled and/or exhaled gases by activating the suction pump at a prompt of the operator or according to a pre-determined interval to draw air past the temperature and humidity sensors in the measuring chamber, and then repeatedly sample the temperature and relative humidity of the inhaled and/or exhaled gases to obtain and store a plurality of sampled heat exchange values during a monitoring interval;   d) compare a first one of the plurality of sampled heat exchange values against the base heat exchange values, and compare each successive one of the plurality of sampled heat exchange values against a preceding one of the sampled heat exchange value to calculate and store a heat gain value corresponding to each of the plurality of sampled heat exchange values;   e) automatically calculate a non-dimensional coupling index from the stored patient data values and from each of the stored heat gain values, the coupling index representing a weighted function of the heat gain in one or more of the plurality of breathing phases; and   f) display the calculated coupling index to the operator via the display means during the monitoring interval relative to pre-defined normal values.   
     
     
         2 . The apparatus of  claim 1 , further comprising an auxiliary adaptor configured to fit between the artificial airway and the adaptor and including a flexible membrane to create pressure differentials by resisting airflow therethrough, and a spirometer in fluid communication therewith to measure tidal or minute volume for use in the calculation of the coupling index. 
     
     
         3 . The apparatus of  claim 1 , wherein the monitoring unit further comprises reference temperature and relative humidity sensors, and wherein the monitoring unit is configured, prior to step (a), to initially calibrate the measuring chamber temperature and relative humidity sensors readings relative to the reference temperature and relative humidity sensor readings, and to apply suitable compensatory correction factors during step (c). 
     
     
         4 . The apparatus of  claim 1 , wherein said measuring chamber further comprises heating resistors for a compensation of heat losses of said inhaled and/or exhaled gases in said measuring chamber, and wherein said monitoring unit is configured to calculate and apply suitable compensatory factors by activation of said heating resistors. 
     
     
         5 . The apparatus of  claim 1 , wherein the wherein the calculated coupling index is displayed relative to pre-defined normal values, and wherein the pre-defined normal values are defined with reference to values that are commonly observed at rest in persons in good general health and who generally match a given patient in gender, age, and body size; or are defined as a specific patient's baseline values at rest or under stress at commencement of the monitoring interval. 
     
     
         6 . An automated diagnostic method for assessing and monitoring the coupling between lung perfusion and ventilation in a patient who is mechanically ventilated or breathing spontaneously through a conventional artificial airway by use of an apparatus comprising:
 an adaptor providing a main path for gases inhaled and/or exhaled by the patient;   a measuring chamber in constant fluid communication with the adaptor but out of the main path of the gases inhaled and/or exhaled by the patient through the adaptor, said measuring chamber comprising temperature and relative humidity sensors for measuring the temperature and humidity of the gases inhaled and/or exhaled by the patient; and,   a monitoring unit in fluid and electrical communication with the measuring chamber, the monitoring unit comprising:
 one of a thermocouple and a flow meter; 
 a suction pump for drawing said inhaled and/or exhaled gases from said adaptor and through said thermocouple or flow meter via said measuring chamber; 
 display and data entry means; and 
   a monitoring unit control system, processor and memory for the acquisition, conversion, and storage of data acquired from the temperature and relative humidity sensors, from the thermocouple or flow meter, and from an operator of the system,   the method comprising:   a) storing patient data values entered by the operator via the data entry means;   b) detecting a plurality of breathing phases of the patient by determining an interval between a low and/or high temperature and/or humidity plateaus between individual inhalations and/or exhalations as measured by the temperature and/or relative humidity sensors;   c) obtaining and storing base heat exchange values from the measured temperature and relative humidity of the inhaled and/or exhaled gases by activating the suction pump at a prompt of the operator or according to a pre-determined interval to draw air past the temperature and humidity sensors in the measuring chamber, and then repeatedly sampling the temperature and relative humidity of the inhaled and/or exhaled gases to obtain and store a plurality of sampled heat exchange values during a monitoring interval;   d) comparing a first one of the plurality of sampled heat exchange values against the base heat exchange values, and compare each successive one of the plurality of sampled heat exchange values against a preceding one of the sampled heat exchange value to calculate and store a heat gain value corresponding to each of the plurality of sampled heat exchange values;   e) automatically calculating a non-dimensional coupling index from the stored patient data values and from each of the stored heat gain values, the coupling index representing a weighted function of the heat gain in one or more of the plurality of breathing phases; and   f) displaying the calculated coupling index to the operator via the display means during the monitoring interval.