Method and system for quantifying timing discrepancies between inspiratory effort and ventilatory assist

Inventors

Sinderby, Christer • Comtois, Norman • Beck, Jennifer • Emtell, Pär • Kock, Michael

Assignees

St Michaels Hospital

Abstract

The present disclosure relates to a method and a system for quantifying timing discrepancies between inspiratory effort and ventilatory assist. A trigger error is determined by comparing a start time of neural inspiration with a start time of the ventilatory assist. A cycling-off error is determined by comparing an end time of the neural inspiration with an end time of the ventilatory assist. The ventilatory assist is synchronized when the trigger error is lower than a first threshold and the cycling-off error is lower than a second threshold. The ventilatory assist may also be characterized in terms of early or late trigger and of early or late cycling-off. A trigger of a ventilator may be adjusted according to the trigger error and a cycling-off of a ventilator may be adjusted according to the cycling-off error.

Core Innovation

The invention provides quantification of ventilatory assist synchronization with a patient's inspiratory effort by comparing timing between a neural inspiration signal and ventilatory assist start and end times. A neural inspiration signal representing an inspiratory effort of the patient is received from one or more electrodes, and a measurement signal representing a start time and an end time of the ventilatory assist is received from the mechanical ventilator. The approach determines a trigger error by comparing the start time of a current inspiratory effort with the start time of the ventilatory assist, and a cycling-off error by comparing the end time of the current inspiratory effort with the end time of the ventilatory assist.

Trigger error and cycling-off error are determined with signal/variability-based exclusions, including ignoring inspiratory efforts in which a variation of the neural inspiration signal is less than a minimum signal variation threshold, and ignoring inspiratory efforts in which a variation of a pressure delivered by the ventilatory assist is less than a minimum pressure variation threshold. The invention defines early trigger error when the ventilatory assist start time precedes the start time of the current inspiratory effort, and late trigger error when the ventilatory assist start time follows the start time of the current inspiratory effort. The invention similarly defines early cycling-off error when the ventilatory assist end time precedes the end time of the current inspiratory effort, and late cycling-off error when the ventilatory assist end time follows the end time of the current inspiratory effort.

The invention further characterizes synchronization by comparing trigger error and cycling-off error to stored thresholds, and adjusting ventilatory assist so that trigger error is lower than a first threshold and cycling-off error is lower than a second threshold. Synchrony can also be evaluated as a trigger-vs-cycling-off error display using an acceptable synchrony region on a graph, and a derived NeuroSync Index is described from breaths within the acceptable synchrony region. The disclosed analysis supports graphical categorization of asynchrony and characterizes timing discrepancy error types such as ineffective triggering, auto-triggering, multiple-EAdi-during-assist, and central apnea.

Claims Coverage

The independent claims include a method claim and a ventilatory support system claim, each built around two core inventive measurements: trigger error and cycling-off error. Across the independent claims, the inventive features include neural inspiration timing, ventilatory assist start/end timing, early/late error definitions, variability-threshold ignoring, threshold-based adjustment, and optional synchronization evaluation by a trigger-versus-cycling-off error graph region.

Across the independent claims, the invention covers determining trigger error and cycling-off error from timing discrepancies between a neural inspiration signal and ventilatory assist start/end times, ignoring low-variation efforts based on minimum signal and pressure variation thresholds, defining early and late error types, and adjusting ventilatory assist so both errors are lowered below respective thresholds; additional claim coverage includes evaluating synchrony using a trigger-versus-cycling-off error graph acceptable area.

Stated Advantages

Documented Applications