Ventilator apparatus and method for operating a ventilator in said ventilator apparatus

Inventors

VAN DER STAAY, Matthias • Friberg, Harri

Assignees

Imtmedical AG

Abstract

The invention is related to ventilation apparatuses and methods for operating a ventilator of a ventilator apparatus. In the method at least one duration ratio factor is set in a computing system of the ventilator apparatus; at least one minute volume, at least one functional dead space volume and at least one time constant are determined; a respiration frequency is computed, based on a previously defined lung model, depending on the determined parameters. The computed respiration frequency is optimized on at least one minimum of a delivered parameter, which is induced to a patient using the ventilator; an inspiratory time and an expiratory time are determined based on the computed respiration frequency and the duration ratio factor; at least one tidal volume based on the previously computed respiration frequency and the determined minute volume is computed; and a delivered respiratory parameter of the ventilator is closed loop controlled.

Core Innovation

The invention relates to an adaptive ventilation mode (AVM) for a ventilator apparatus. The ventilator apparatus includes at least one actuator driven by at least one computing system, and the computing system executes a program to compute a respiration frequency (f) based on a previously defined lung model (LM) using minute volume (Mv), functional dead space (Vd), time constant (R*C), and duration ratio factors (D1, D2) stored in memory.

The computed respiration frequency (f) is optimized on at least one minimum of a delivered parameter (Gtot) induced to the patient using the ventilator, and is further optimized based on a percentage of spontaneous breaths of the patient (% Support). The computation changes depending on whether % Support is less than 1 or greater than 1, using different sets of lung model-dependent parameters for the computation.

After computing respiration frequency (f), the program estimates an inspiratory time (Ti) and an expiratory time (Te) based on the computed respiration frequency (f) and the duration ratio factors (D1, D2). The program also computes at least one tidal volume (Vt) based on the computed respiration frequency (f) and the minute volume (Mv). A closed loop controller connected to the computing system controls the ventilator actuators based on output data representing a delivered respiratory parameter including respiratory pressure (Rp), respiratory volume (Rv), and/or respiratory flow (Rf), thereby delivering the respiratory parameter to the patient.

Embodiments include iterative computation of respiration frequency (f) using fixed-point iteration and/or Newton root-finding, and different lung model forms including a linear lung model (ILM) and a nonlinear lung model (nLM) with assumed respiratory pressure/flow waveforms such as rectangular, exponential, sinusoidal, or saw tooth. Safety limits are included for Ti/Te and for PEEP and intrinsic PEEP (PEEP_intr), and device architecture is described including the computing system, transducers, A/D and D/A converters, actuator/valve, and user interface, with optional gas source embodiments.

Claims Coverage

The document provides one independent claim (clm-00001). It includes a ventilation-control scheme with six inventive features: model-based computation of respiration frequency, optimization against a delivered parameter with adaptation to % Support, estimation of inspiratory and expiratory times, computation of tidal volume, and closed-loop control of delivered respiratory parameters using ventilator actuators.

Overall, the claim coverage centers on AVM using a previously defined lung model to compute and optimize respiration frequency as a function of Mv, Vd, R*C, and D1/D2, adapt the computation based on % Support, then derive Ti/Te and Vt and implement closed-loop control to deliver respiratory pressure, volume, or flow via ventilator actuators.

Stated Advantages

Documented Applications