Respiratory device and method for controlling a respiratory device

Abstract

The invention relates to a respiratory device comprising a respiratory gas source ( 20 ). a control unit ( 13 ) and a connecting device for connecting to a respiratory mask. The control unit is connected to at least one sensor ( 15 ) for detecting a measurement parameter. The inventive method controls the respiratory device. The control unit has a step generator ( 19 ) for specifying a stepped modification of the pressure that.is generated by the respiratory gas source. The sensor is configured to measure a signal that corresponds to the pressure distribution and is coupled to an analyser ( 18 ). The analyser evaluates the temporal distribution of an analysis signal that is dependent on the measuring signal and the step generator increases the pressure by a pressure step in a respiratory cycle that follows the measuring evaluation, if the analyser determines a deviation of the analysis signal from a limit value after a predeterminable time limit has elapsed following the pressure increase. The deviation must exceed a predeterminable minimum differential in order to trigger a pressure increase.

1 . Ventilation device with a breathing gas source, a control unit, and a connecting device for connecting the device to a ventilation mask, where the control unit is connected to at least one sensor for detecting a test parameter, wherein
 the control unit ( 1 ) has a step generator ( 19 ) for determining an at least temporary, essentially stepped change in the inspiratory pressure produced by the breathing gas source ( 20 ); in that   the sensor ( 15 ) is designed to measure a signal corresponding to the change in pressure and is connected to an analyzer ( 18 ), which evaluates the change over time in an analysis signal dependent on the measuring signal; and in that   the step generator ( 19 ) increases the pressure by a pressure step during a ventilation cycle following that in which measured value was evaluated if, after a predetermined time limit has elapsed following the pressure increase, the analyzer ( 18 ) determines that the analysis signal deviates from a limit value by more than a predetermined minimum difference.   
     
     
         2 . Device according to  claim 1 , wherein the analyzer is designed to evaluate the changes in the ventilation volume as an analysis signal. 
     
     
         3 . Device according to  claim 1 , wherein the analyzer ( 18 ) is designed to analyze a flow curve as an analysis signal. 
     
     
         4 . Device according to  claim 1 , wherein the analyzer ( 18 ) is designed to detect a decrease in the maximum ventilation volume from breath to breath at constant inspiratory pressure. 
     
     
         5 . Device according to  claim 1 , wherein the analyzer ( 18 ) is designed to detect a decrease in the flow occurring at a predetermined time after a sudden pressure increase. 
     
     
         6 . Device according to  claim 1 , wherein the sensor ( 15 ) is designed as a flow sensor. 
     
     
         7 . Device according to  claim 1 , wherein an integrator ( 17 ) is connected downstream from the sensor ( 15 ). 
     
     
         8 . Device according to  claim 1 , wherein the control unit ( 13 ) lowers the pressure by a pressure step via the step generator ( 19 ) the first time a reduction of the ventilation volume following a pressure increase is not detected. 
     
     
         9 . Device according to  claim 1 , wherein the control unit ( 13 ) is connected to a setpoint memory for ventilation volume setpoints. 
     
     
         10 . Device according to  claim 1 , wherein the control unit ( 13 ) is connected to a square-wave generator for defining the pressure curves during the inspiration and expiration phases. 
     
     
         11 . Device according to  claim 1 , wherein the control unit ( 13 ) is connected to a curve generator for defining the pressure curves during the inspiration and expiration phases. 
     
     
         12 . Device according to  claim 1 , wherein the analyzer ( 18 ) evaluates a pressure difference between the inspiration phases and the expiration phases. 
     
     
         13 . Device according to  claim 1 , wherein the step generator ( 19 ) lowers the expiratory pressure to increase the pressure difference. 
     
     
         14 . Method for controlling a ventilator, in which a breathing gas source is controlled by a control unit as a function of at least one test parameter, wherein the
 control unit ( 13 ) produces an at least temporary, essentially stepped change in the pressure generated by the breathing gas source ( 20 ); in that   the sensor ( 15 ) detects a measuring signal corresponding to the change in pressure; and in that   the change over time in an analysis signal dependent on the measuring signal is evaluated, and the inspiratory pressure is increased in a subsequent ventilation cycle whenever the analysis signal deviates from a limit value by a predetermined minimum difference at a minimum of one predetermined time.   
     
     
         15 . Method according to  claim 14 , wherein a decrease in the ventilation volume relative to the ventilation volume observed immediately after a pressure increase is detected, and in that the control unit ( 13 ) increases the pressure precisely when the decrease in the ventilation volume exceeds a predetermined minimum difference after a predetermined time following the pressure increase has elapsed. 
     
     
         16 . Method according to  claim 14 , wherein, following an at least approximate step-like pressure increase, the pressure curve realized during the preceding breath is maintained if a decreasing flow at essentially constant pressure is detected after a predetermined time interval following the step-like pressure increase. 
     
     
         17 . Method according to  claim 14 , wherein the sensor ( 15 ) carries out a flow measurement. 
     
     
         18 . Method according to  claim 15 , wherein the volume signal is produced by integration of the flow signal. 
     
     
         19 . Method according to  claim 14 , wherein the pressure is lowered by a pressure step the first time a decrease in the ventilation volume following a pressure increase is not detected. 
     
     
         20 . Method according to  claim 14 , wherein the control unit ( 13 ) considers a target value for the ventilation volume. 
     
     
         21 . Method according to  claim 14 , wherein the ventilation pressure is controlled according to the course of a square-wave signal. 
     
     
         22 . Method according to  claim 14 , wherein the ventilation pressure is varied by the control unit ( 13 ) according to a predetermined pressure curve. 
     
     
         23 . Method according to  claim 14 , wherein a pressure difference between the inspiratory and expiratory pressure is determined. 
     
     
         24 . Method according to  claim 14 , wherein the pressure difference is increased by lowering the expiratory pressure. 
     
     
         25 . Method according to  claim 14 , wherein a pressure is changed from ventilation cycle to ventilation cycle. 
     
     
         26 . Method according to  claim 14 , wherein the pressure is held constant for at least two successive inspiration phases. 
     
     
         27 . Method according to  claim 14 , wherein the pressure is held constant for at least two successive expiration phases. 
     
     
         28 . Method according to  claim 14 , wherein the control unit ( 13 ) decreases the pressure only when an actual value of the ventilation volume exceeds the predetermined setpoint. 
     
     
         29 . Method according to  claim 14 , wherein, in a first step, the control unit ( 13 ) increases the pressure until the ventilation volume reaches the predetermined setpoint, and in that an additional pressure increase is then carried out. 
     
     
         30 . Method according to  claim 14 , wherein an at least approximate square-wave form pressure increase is selected for at least a single breath. 
     
     
         31 . Method according to  claim 30 , wherein the flow curve following the stepped pressure increase is analyzed for the presence of an increase to a maximum and a subsequent decelerating curve.