Patent ID: 8109269

Claim:
A method of automatically controlling a respiration system for proportional assist ventilation of a subject with a control means and with a ventilator, which delivers a breathing gas with a pressure preset by the control unit, the method comprising the steps of: recording an electric signal using electrodes on the chest of the subject with the signal generated by electromyography or using sensors on the chest with the signal generated by mechanomyography; subjecting the signal to signal processing in the control means in order to obtain a signal u emg (t) representing the breathing activity; determining the respiratory muscle pressure p mus (t) by calculating p mus (t) from one of: measured values for an airway pressure and a volume flow Flow(t) as well as from the lung mechanical parameters of the patient in the control unit, the respiratory muscle pressure being equated with a negative airway pressure −p occl (t) measured during an occlusion, and determined values provided by means of an esophageal catheter, which is equipped with pressure sensors for measuring one or more of an intrathoracic pressure p es (t) and an abdominal pressure p abd (t), by equating with a transdiaphragmal pressure p abd (t)−p es (t), where p abd (t) can be optionally assumed to be constant; transforming the breathing activity signal u emg (t) into a pressure signal p emg (u emg (t)) by means of a preset transformation rule, the transformation rule being determined such that a mean deviation of the resulting transformed pressure signal p emg (t) is minimized by the respiratory muscle pressure p mus (t) determined; determining a respiratory effort pressure p pat (t) by the control unit as a weighted mean according to p pat (t)=a·p mus (t)+(1−a)·p emg (t), in which a is a parameter selected under the boundary condition 0≦a≦1; calculating the airway pressure p aw (t) to be delivered by the ventilator of the respiration system in the control unit by a sliding adaptation as a function of preselected degrees of assist VA Volume Assist (VA) for the compensation of elastic recoil forces/resistances and Flow Assist (FA) for a compensation of the resistive forces as p aw ⁡ ( t i ) = k 0 + ∑ j = 1 n ⁢ k j · p aw ⁡ ( t i - j ) + ∑ j = 0 n ⁢ h j · p pat ⁡ ( t i - j ) in which t i is a current point in time and t i−j , j=1, . . . , n, are previous points in time of a periodical time-discrete sampling and k j and h j , in which j=1, . . . , n, are parameters dependent on resistance (R), elastance (E), positive end-expiratory pressure (PEEP), intrinsic PEEP (iPEEP), VA, FA and the sampling time Δt, and the ventilator is set by the control unit so as to provide said airway pressure p aw (t i ).