Abstract: An auxiliary device and a method for estimating the muscle pressure of a patient being ventilated by a pulmonary ventilator is provided which comprises creating the database that correlates data on pressure, volume and flow of pulmonary ventilator respiratory cycles with muscle pressure data corresponding to the pressure, volume and flow data of the ventilator; using the database to create a training data set; training a predictive time-series algorithm with the training data set; populating the algorithm with pressure, volume and flow data from a pulmonary ventilator, in which the pressure, volume and flow data include at least a time series with pressure, volume and flow curve points; and using the algorithm to estimate the muscle pressure value for at least one of the time series points.