Non-invasive method and apparatus for optimizing the respiration of atelectatic lungs

Apparatus for providing ventilatory settings with regard to airway pressure levels of an artificial ventilator, said artificial ventilator is connectable to a lung,

• comprising:
• a sensor for measuring samples of gas concentration in an expired gas during a single breath for several breaths;
• an analog to digital converter for obtaining first data samples of said gas concentration of the expired gas over the single breath in a time domain;
• data processor for selecting a plurality of second data samples from said first data samples, said data processor to exclude data samples representing airway gas only;
• said data processor for calculating a tracing value being sensitive to changes of alveolar dead space on a basis of said second data samples, wherein the tracing value is represented by an angle between an endtidal mean slope of the gas concentration in the expired gas and a steepest mean slope of the gas concentration in the expired gas during the single breath;
• and
• said data processor for detecting, during a change of at least one airway pressure level of the artificial ventilator, from a resulting course of a plurality of tracing values during a course of a sequential increase of a peak inspiratory pressure of the artificial ventilator followed by a sequential decrease of a positive end expiratory pressure, airway pressure levels at which alveolar opening or lung overdistension or lung open condition or alveolar closing occurs;
• wherein the gas concentration represents a CO2 concentration;
• and
• wherein when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung opening is detected if the angle reaches a maximal decrease, and when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung overdistension is detected if the angle results in a decrease of about 10% from its previous value, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, an open-lung condition is detected if the angle results in a minimal value observed before a closing pressure is detected, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, a closing pressure of the lungs is detected if a curve of the tracing values of the angle shows a permanent gradient change after a point corresponding to open-lung condition values.

Method for providing ventilatory settings with regard to airway pressure levels of an artificial ventilator, said artificial ventilator is connectable to a lung,

• comprising the steps of:
• a) obtaining data samples of gas concentration of an expired gas over a single breath, said data samples of gas concentration comprising of gas originating from an airway and/or alveoli of a lung;
• b) selecting a plurality of data samples from obtained data samples from step a) excluding data samples representing airway gas only;
• c) calculating a tracing value being sensitive to changes of alveolar dead space on a basis of selected data samples from said step b), wherein the tracing value consists of an angle of intersection between a first slope of a first phase and a second slope of a second phase of the gas concentration in the expired gas during the single breath, wherein the first slope of the first phase consists of an endtidal mean slope which is determined by the endtidal mean slope in a plot either over time or over volume of the gas concentration in the expired gas towards the final stage of the single breath, and wherein the second slope of the second phase consists of a steepest mean slope which is determined by the steepest mean slope in a plot either over time or over volume of the gas concentration in the expired gas in a vicinity of a point of inflection;
• d) changing at least one airway pressure level of the artificial ventilator and then repeating steps a), b) and c) for obtaining a plurality of tracing values;
• and
• e) observing a resulting course of the plurality of tracing values during a course of a sequential increase of a peak inspiratory pressure of the artificial ventilator followed by a sequential decrease of a positive end expiratory pressure, and from the observation of the resulting course, detecting airway pressure levels at which alveolar opening or lung overdistension or lung open condition or alveolar closing occurs;
• wherein the gas concentration represents a CO2 concentration;
• and
• wherein when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung opening is detected if the angle reaches a maximal decrease, and when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung overdistension is detected if the angle results in a decrease of about 10% from its previous value, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, an open-lung condition is detected if the angle results in a minimal value observed before a closing pressure is detected, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, a closing pressure of the lungs is detected if a curve of the tracing values of the angle shows a permanent gradient change after a point corresponding to open-lung condition values.

Apparatus for providing ventilatory settings with regard to airway pressure levels of an artificial ventilator, said artificial ventilator is connectable to a lung,

• comprising:
• a sensor for measuring samples of gas concentration in an expired gas during a single breath for several breaths;
• an analog to digital converter for obtaining first data samples of said gas concentration of the expired gas over the single breath in a time domain;
• data processor for selecting a plurality of second data samples from said first data samples, said data processor to exclude data samples representing airway gas only;
• said data processor for calculating a tracing value being sensitive to changes of alveolar dead space on a basis of said second data samples, wherein the tracing value consists of an angle of intersection between a first slope of a first phase and a second slope of a second phase of the gas concentration in the expired gas during each single breath, wherein the first slope of the first phase consists of an endtidal mean slope which is determined by the endtidal mean slope in a plot either over time or over volume of the gas concentration in the expired gas towards the final stage of the single breath, and wherein the second slope of the second phase consists of a steepest mean slope which is determined by the steepest mean slope in a plot either over time or over volume of the gas concentration in the expired gas in a vicinity of a point of inflection;
• said data processor for detecting, during a change of at least one airway pressure level of the artificial ventilator, from a resulting course of a plurality of tracing values during a course of a sequential increase of the peak inspiratory pressure of the artificial ventilator followed by a sequential decrease of the positive end expiratory pressure, airway pressure levels at which alveolar opening or lung overdistension or lung open condition or alveolar closing occurs;
• wherein the gas concentration represents a CO2 concentration;
• and
• wherein when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung opening is detected if the angle reaches a maximal decrease, and when the peak inspiratory pressure of the artificial ventilator is increased continuously, a lung overdistension is detected if the angle results in a decrease of about 10% from its previous value, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, an open-lung condition is detected if the angle results in a minimal value observed before a closing pressure is detected, and when the positive end expiratory pressure of the artificial ventilator is decreased continuously, a closing pressure of the lungs is detected if a curve of the tracing values of the angle shows a permanent gradient change after a point corresponding to open-lung condition values.