Apparatus and method for identifying FRC and PEEP characteristics

Abstract

A ventilator for ventilating a patient also assists a clinician in determining a suitable PEEP for the patient. For this purpose, a graph or tabular display of a series of different value PEEPs and corresponding functional residual capacities of the patient may be provided. Or, the relationship between lung compliance and a series of different values of PEEP may be provided. Or, the amount of the lung volume recruited/de-recruited at various levels of PEEP may be determined for use in selecting a desired PEEP. To this end, the functional residual capacity of the lungs is determined for a first PEEP level. The PEEP is then altered to a second level and a spirometry dynostatic curve of lung volume and pressure data is obtained. The lung volume on the dynostatic curve at a lung pressure corresponding to the first PEEP value is obtained. The difference between the functional residual capacity of the lungs at the first PEEP level and that determined from the dynostatic curve represents the lung volume recruited/de-recruited when changing between said first and second PEEPs.

1 - 55 . (canceled)  
   
   
       56 . A ventilator for ventilating a patient and for determining a relationship between a ventilator parameter and the functional residual capacity of the patient, said ventilator comprising: 
 at least one gas flow control valve ( 20 ,  24 ,  54 ) in a flow path ( 32 ) for breathing gases of the patient and a controller ( 26  or  74 ) for said at least one gas flow control valve establishing and altering a parameter of the ventilation supplied to the patient;    a gas analyzer ( 70 ) measuring a compositional characteristic of the breathing gases of the patient;    a sensor ( 62 ) measuring a quantitative characteristic of the breathing gases of the patient;    a central processing unit ( 26  or  74 ) coupled to said gas analyzer and sensor and determining the functional residual capacity of the patient at a plurality of parameter values; and    a display ( 102 ) coupled to said central processing unit and displaying data relating functional residual capacity to corresponding parameter values.    
   
   
       57 . The ventilator according to  claim 56  wherein said at least one gas flow control valve and controller establish and alter a parameter comprising the PEEP supplied to the patient, said central processing unit is further defined as determining the functional residual capacity of the patient at a plurality of PEEPs, and said display displays data relating functional residual capacity to corresponding PEEP levels.  
   
   
       58 . The ventilator according to  claim 57  wherein said at least one gas flow control valve and controller increment or decrement the PEEP.  
   
   
       59 . A ventilator according to  claim 56  wherein said central processing unit determines the functional residual capacity of the patient by an inert gas wash-in or wash-out technique.  
   
   
       60 . The ventilator according to  claim 59  wherein the ventilator provides breathing gases containing oxygen and nitrogen to the patient and wherein said at least one gas flow control valve and said controller alter the amount of oxygen contained in the breathing gases supplied to the patient.  
   
   
       61 . The ventilator according to  claim 57  wherein said display displays data relating PEEP to the corresponding functional residual capacity in graphic form.  
   
   
       62 . The ventilator according to  claim 57  wherein said display displays data relating PEEP to the corresponding functional residual capacity in tabular form.  
   
   
       63 . The ventilator according to  claim 62  wherein the tabular display includes an indication of PEEPe and PEEPi with the corresponding functional residual capacity.  
   
   
       64 . The ventilator according to  claim 57  wherein said controller sets one or more of initial PEEP, end PEEP, number of measurements, or increment/decrement of PEEP alteration.  
   
   
       65 . The ventilator according to  claim 56  further defined as including a memory for storing data relating functional residual capacity to corresponding parameter values.  
   
   
       66 . The ventilator according to  claim 56  wherein said display displays data obtained at different times.  
   
   
       67 . The ventilator according to  claim 56  wherein said at least one gas flow control valve and controller alter one of a respiration rate, expiration time, or inspiratory:expiratory ratio parameter; said central processing unit determines the functional residual capacity of the patient at a plurality of different values for the altered parameter, and said display displays data relating functional residual capacity to corresponding parameter values.  
   
   
       68 . The ventilator according to  claim 57  wherein said at least one gas flow control value and said controller carry out a recruitment maneuver and said display displays data obtained prior and subsequent to the recruitment maneuver.  
   
   
       69 . A method determining a relationship between a ventilation parameter and the functional residual capacity of a ventilated patient, said method comprising the steps of: 
 (a) causing alteration in a parameter of the ventilation supplied to the patient;    (b) determining the functional residual capacity of the patient at a plurality of parameter values; and    (c) displaying data relating to functional residual capacity to corresponding parameter values.    
   
   
       70 . The method according to  claim 69  wherein step (a) is further defined as causing an alteration in the PEEP supplied to the patient, step (b) is further defined as determining the functional residual capacity of the patient at a plurality of PEEPs, and step (c) is further defined as displaying data relating functional residual capacity to corresponding PEEP levels.  
   
   
       71 . The method according to  claim 70  wherein step (a) is further defined as incrementing or decrementing the PEEP.  
   
   
       72 . The method according to  claim 70  wherein step (b) is further defined as determining the functional residual capacity of the patient by an inert gas wash-in or wash-out technique.  
   
   
       73 . The method according to  claim 72  wherein the ventilated patient is provided with breathing gases containing oxygen and nitrogen and wherein step (b) is further defined as altering the amount of oxygen contained in the breathing gases provided to the patient.  
   
   
       74 . The method according to  claim 70  wherein step (c) is further defined as displaying data relating PEEP to the corresponding functional residual capacity in graphic form.  
   
   
       75 . The method according to claim  14  wherein step (c) is further defined as displaying data relating PEEP to the corresponding functional residual capacity in tabular form.  
   
   
       76 . The method according to  claim 75  wherein step (c) is further defined as displaying an indication of PEEPe and PEEPi with the corresponding functional residual capacity.  
   
   
       77 . The method according to  claim 70  including a step for setting one or more of initial PEEP, end PEEP, number of measurements, or increment/decrement of PEEP alteration.  
   
   
       78 . The method according to  claim 69  further defined as storing data relating to functional residual capacity to corresponding parameter values.  
   
   
       79 . The method according to  claim 78  further defined as displaying data obtained at different times.  
   
   
       80 . The method according to  claim 69  wherein step (a) is further defined as causing an alteration in one of a respiration rate, expiration time, or inspiratory:expiratory ratio parameter; step (b) is further defined as determining the functional residual capacity of the patient at a plurality of different values for the altered parameter, and step (c) is further defined as displaying data relating functional residual capacity to corresponding parameter values.  
   
   
       81 . The method according to  claim 69  further including step of carrying out a recruitment maneuver and step (c) is further defined as displaying data obtained prior and subsequent to the recruitment maneuver.  
   
   
       82 . Apparatus for indicating recruitment/de-recruitment of lung volume in association with varying levels of PEEP for a ventilated patient, said apparatus comprising: 
 at least one gas flow control valve in a breathing gas flow path and a controller for said at least one valve for ventilating the patient from a ventilator, said at least one gas flow control valve and controller ventilating the patient with a first level of PEEP, altering the PEEP to a second level, different than said first level, and ventilating the patient with the second level of PEEP;    means for measuring the functional residual capacity of the patient at one of the first and second levels of PEEP;    means for determining a spirometry dynostatic curve for the breathing action of the patient at the other of said first and second levels of PEEP;    means for determining a lung volume difference for the functional residual capacity at the one level of PEEP and a point on the dynostatic curve for the other level of PEEP corresponding to the one level of PEEP; and    a display for displaying the lung volume difference as recruited/de-recruited volume in the lungs when changing between the first and second levels of PEEP.    
   
   
       83 . The apparatus according to  claim 82  wherein said at least one gas flow control valve and controller alters the PEEP from a higher level to a lower level.  
   
   
       84 . The apparatus according to  claim 82  wherein said means for determining a spirometry dynostatic curve is further defined as determining a spirometry dynostatic curve on an absolute scale using functional residual capacity.  
   
   
       85 . The apparatus according to  claim 82  wherein said display displays the lung volume differences at various PEEPs in conjunction with functional residual capacities of the lungs.  
   
   
       86 . The apparatus according to  claim 85  wherein said display graphically displays the lung volume differences and functional residual capacities.  
   
   
       87 . The apparatus according to  claim 85  wherein said display displays the recruited/de-recruited volumes and functional residual capacities in tabular form.  
   
   
       88 . The apparatus according to  claim 82  further including means for performing a recruitment maneuver on the patient.  
   
   
       89 . A method for indicating recruitment/de-recruitment of lung volume in association with varying levels of PEEP for a ventilated patient, said method comprising the steps of: 
 (a) ventilating the patient with a first level of PEEP, altering the PEEP to a second level, different than said first level, and ventilating the patient with the second level of PEEP;    (b) measuring the functional residual capacity of the patient at one of the first and second levels of PEEP;    (c) determining a spirometry dynostatic curve for the breathing action of the patient at the other of said first and second levels of PEEP;    (d) determining a lung volume difference for the functional residual capacity at the one level of PEEP and a point on the dynostatic curve for the other level of PEEP corresponding to the one level of PEEP; and    (e) displaying the lung volume difference as recruited/de-recruited volume in the lungs when changing between the first and second levels of PEEP.    
   
   
       90 . The method of  claim 89  wherein step (a) alters the PEEP from a higher level to a lower level.  
   
   
       91 . The method according to  claim 89  further including an initial step of performing a recruitment maneuver on the patient.  
   
   
       92 . The method according to  claim 89  wherein step (c) is further defined as determining a spirometry dynostatic curve on an absolute scale using functional residual capacity.  
   
   
       93 . The method according to  claim 89  further defined as displaying the lung volume differences at various PEEPs in conjunction with functional residual capacities of the lung.  
   
   
       94 . The method according to  claim 93  further defined as graphically displaying the lung volume differences and functional residual capacities.  
   
   
       95 . The method according to  claim 93  further defined as displaying the recruited/de-recruited volumes and functional residual capacities in tabular form.  
   
   
       96 . The method according to  claim 89  further defined as repeating the steps of the method by ventilating the patient at the other of the first and second levels of PEEP, altering the PEEP to a third level, and carrying out the corresponding steps of the method.  
   
   
       97 . A ventilator for ventilating a patient and for determining a relationship between a ventilator parameter and a functional residual capacity characteristic of the patient, said ventilator comprising: 
 at least one gas flow control valve in a flow path for breathing gases of the patient and a controller for said at least one gas flow control valve for establishing and altering a PEEP supplied to the patient;    a gas analyzer measuring a compositional characteristic of the breathing gases of the patient;    a sensor measuring a quantitative characteristics of the breathing gases of the patient;    a central processing unit coupled to said gas analyzer and sensor for determining the functional residual capacity of the patient at a plurality of PEEP values and for determining the relationship between increments in the alteration in PEEP and resulting differences in functional residual capacity; and    a display coupled to said central processing unit and displaying data presenting the relationship determined by said central processing unit to corresponding values of PEEP.    
   
   
       98 . The ventilator according to  claim 97  wherein said at least one gas flow control valve and controller increment or decrement the PEEP.  
   
   
       99 . A ventilator according to  claim 97  wherein said central processing unit determines the functional residual capacity of the patient by an inert gas wash-in or wash-out technique.  
   
   
       100 . A ventilator according to  claim 99  wherein said ventilator provides breathing gases containing oxygen and nitrogen to the patient and wherein said at least one gas flow control valve and controller alter the amount of oxygen contained in the breathing gases supplied to the patient.  
   
   
       101 . The ventilator according to  claim 97  wherein said display displays data presenting the relationship determined by said central processing unit to corresponding PEEP values in graphic form.  
   
   
       102 . The ventilator according to  claim 97  wherein said display displays data presenting the relationship determined by said central processing unit to corresponding PEEP values in tabular form.  
   
   
       103 . The ventilator according to  claim 102  wherein the tabular display includes an indication of PEEPe and PEEPi with corresponding PEEP values.  
   
   
       104 . The ventilator according to  claim 97  wherein said controller sets one or more of initial PEEP, end PEEP, number of measurements, or increment/decrement of PEEP alteration.  
   
   
       105 . The ventilator according to  claim 97  further defined as including a memory for storing data relating the relationship determined by means (c) to corresponding PEEP values.  
   
   
       106 . A method determining a relationship between a ventilation parameter and a functional residual capacity characteristic of a ventilated patient, said method comprising the steps of: 
 (a) causing alteration in a PEEP supplied to the patient;    (b) determining the functional residual capacity of the patient at a plurality of PEEP values;    (c) determining the relationship between increments in the alteration in PEEP and resulting differences in functional residual capacity; and    (d) displaying data presenting the relationship determined in step (c) to  10  corresponding values of PEEP.    
   
   
       107 . The method according to  claim 106  wherein step (a) is further defined as incrementing or decrementing the PEEP.  
   
   
       108 . The method according to  claim 106  wherein step (b) is further defined as determining the functional residual capacity of the patient by an inert gas wash-in or wash-out technique.  
   
   
       109 . The method according to  claim 106  wherein step (d) is further defined as displaying data presenting the relationship determined in step (c) to corresponding PEEP values in graphic form.  
   
   
       110 . The method according to  claim 106  wherein step (c) is further defined as displaying data presenting the relationship determined in step (c) to corresponding PEEP values in tabular form.  
   
   
       111 . The method according to  claim 110  wherein step (d) is further defined as displaying an indication of PEEPe and PEEPi with the corresponding PEEP values.  
   
   
       112 . The method according to  claim 106  including a step for setting one or more of initial PEEP, end PEEP, number of measurements, or increment/decrement of PEEP alteration.  
   
   
       113 . The method according to  claim 106  further defined as storing data relating the relationship determined in step (c) to corresponding PEEP values.