Ventilator apparatus and method for operating a ventilator in said ventilator apparatus
Inventors
VAN DER STAAY, Matthias • Friberg, Harri
Assignees
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Publication Number
US-10357624-B2
Publication Date
2019-07-23
Expiration Date
Abstract
The invention comprises a ventilation apparatus and method for operating a ventilator of a ventilator apparatus, wherein 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 said determined parameters, where said computed respiration frequency is optimized on at least one minimum of a delivered parameter, which is induced to a patient using said ventilator; an inspiratory time and an expiratory time are determined based on said computed respiration frequency and said duration ratio factor; at least one tidal volume based on said previously computed respiration frequency and said determined minute volume is computed; and a delivered respiratory parameter of the ventilator is closed loop controlled.
Core Innovation
The ventilator apparatus is operated in an adaptive ventilation mode by setting at least one duration ratio factor (D1, D2) in a computing system. The computing system determines at least one minute volume (Mv), determines at least one functional dead space (Vd), and determines at least one time constant (R*C). Using a previously defined lung model (LM) that depends on the determined minute volume (Mv), the determined functional dead space (Vd), and the determined time constant (R*C), the computing system computes a respiration frequency (f) based on the set duration ratio factor (D1, D2).
The computed respiration frequency (f) is optimized on at least one minimum of a delivered parameter (G_tot) induced to a patient using the ventilator, and in some embodiments the minimum is a delivered mechanical respiration work (W_tot). The method determines an inspiratory time (Ti) and an expiratory time (Te) based on the computed respiration frequency (f) and the set duration ratio factor (D1, D2), and computes at least one tidal volume (Vt) based on the computed respiration frequency (f) and the determined minute volume (Mv).
Finally, the ventilator apparatus performs closed loop controlling of at least one of a delivered respiratory parameter, including respiratory pressure (Rp), respiratory flow (Rf), or respiratory volume (Rv). The closed loop controlling is based on the computations performed for respiration frequency (f), inspiratory time (Ti), expiratory time (Te), and tidal volume (Vt), thereby adapting delivered ventilation to the patient through optimization of the delivered parameter (G_tot).
Claims Coverage
The document provides one independent claim directed to an operating method for a ventilator using an adaptive ventilation mode that computes respiration frequency (f) from minute volume (Mv), functional dead space (Vd), time constant (R*C), and duration ratio factors (D1, D2), followed by computation of Ti, Te, and Vt and closed-loop control of delivered respiratory pressure, flow, or volume. Dependent claims refine the optimization objective, specify determination approaches for Mv and Vd, and impose constraints on Ti and Te.
Adaptive computation and optimization of respiration frequency
computing a respiration frequency (f) using said computing system, based on a previously defined lung model (LM), depending on said determined minute volume (Mv), said determined functional dead space (Vd), said determined time constant (R*C) and said set duration ratio factor (D1, D2), where said computed respiration frequency (f) is optimized on at least one minimum of a delivered parameter (G_tot), which is induced to a patient using said ventilator.
Deriving inspiratory/expiratory times and tidal volume from optimized frequency
determining an inspiratory time (Ti) and an expiratory time (Te) based on said computed respiration frequency (f) and said set duration ratio factor (D1, D2) using said computing system; computing at least one tidal volume (Vt) based on said computed respiration frequency (f) and said determined minute volume (Mv) using said computing system.
Closed-loop controlling of delivered respiratory pressure/flow/volume
closed loop controlling at least one of a delivered respiratory parameter of the ventilator including at least one of a respiratory pressure (Rp), a respiratory flow (Rf) or a respiratory volume (Rv) of the ventilator based on the computations.
Duration-factor-driven ventilator operation with minute volume, dead space, and time constant determination
setting at least one duration ratio factor (D1, D2) in a computing system of the ventilator apparatus; determining at least one minute volume (Mv) using said computing system; determining at least one functional dead space (Vd) using said computing system; determining at least one time constant (R*C) using said computing system.
Across the independent claim, the inventive concept is to set duration ratio factors (D1, D2), determine minute volume (Mv), functional dead space (Vd), and time constant (R*C), then compute respiration frequency (f) via a lung model (LM) and optimize f on a minimum of a delivered parameter (G_tot), followed by deriving Ti, Te, and Vt and closed-loop controlling of delivered respiratory pressure, flow, or volume based on those computations. Dependent claims further specify optimization refinements and constraints on Ti and Te, while specifying how functional dead space (Vd) can be determined.
Stated Advantages
Optimizes the computed respiration frequency (f) on at least one minimum of a delivered parameter (G_tot) induced to a patient using the ventilator.
Enables closed loop controlling of delivered respiratory pressure (Rp), respiratory flow (Rf), or respiratory volume (Rv) based on computations of frequency and corresponding timing and volume.
Allows refinement of the optimization objective for f to a minimum of delivered mechanical respiration work (W_tot).
Provides extremum-based limits for inspiratory time (Ti) and expiration time (Te) based on time constant (R*C) and related patient/model parameters.
Determines functional dead space (Vd) using volumetric capnography with carbon dioxide measurement and proximal flow measurement.
Documented Applications
Ventilation in an adaptive ventilation mode (AVM) implemented in a ventilator apparatus by computing respiration frequency (f), inspiratory time (Ti), expiratory time (Te), tidal volume (Vt), and performing closed-loop control of delivered respiratory pressure, flow, or volume.
Optimization embodiments that minimize delivered mechanical respiration work (W_tot) delivered to a patient using at least one actuator of a ventilator.
Functional dead space (Vd) determination using volumetric capnography with carbon dioxide measurement and proximal flow measurement.
Limiting inspiratory time (Ti) and expiration time (Te) using extremum-based limits with thresholds derived from time constant (R*C) and patient-specific maximum inspiration time derived from ideal body weight (IBW).
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