Mechanical Lung Ventilation Pressure Synchronization
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Solution Overview
Problem
Current lung ventilation methods using mechanical ventilators can result in elevated airway pressures, leading to patient discomfort and increased risks of lung stress and CO2 rebreathing due to overlapping tidal and functional residual capacity (FRC) volumes during Airway Pressure Release Ventilation (APRV) cycles.
Innovation Solution
A method that synchronizes positive and negative pressure cycles with baseline pressure changes, allowing patients to breathe spontaneously at both high and low pressure levels, while maintaining baseline pressure during inspiration and switching after a delay to prevent overlapping and optimize CO2 removal above and below FRC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If positive pressure cycles are applied intermittently with PEEP higher than atmospheric pressure, then lung ventilation support is provided, but peak pressure (PIP+PEEP) becomes elevated which can be harmful for the patient's respiratory system
Solution Approach 1:
The patent segments the ventilation cycle into distinct phases: a first pressure level phase for CO2 removal from volumes above FRC, and a second pressure level phase for CO2 removal from FRC. This segmentation allows separate control of tidal volumes and FRC volumes, preventing overlapping that causes gas trapping and reducing peak pressure requirements while maintaining effective ventilation support.
Solution Approach 2:
The patent applies preliminary action by establishing a baseline PEEP level before delivering positive pressure cycles. The PEEP is maintained at a level that prevents alveolar collapse during expiration, and the ventilator is configured to synchronize pressure cycles with patient breathing efforts, ensuring that pressure support is applied at the optimal moment to avoid elevated peak pressures while maintaining ventilation effectiveness.
2Productivity
If APRV cycles are used to provide ventilation, then CO2 removal is achieved, but overlapping tidal and FRC volumes occur which increases risks of gas trapping and CO2 rebreathing
Solution Approach 1:
The patent employs feedback mechanisms by monitoring patient breathing efforts and using this information to synchronize pressure level transitions. The ventilator detects patient inspiration efforts within a trigger time window and adjusts the timing of pressure level changes accordingly, ensuring that tidal volume exhalation is complete before FRC volume exchange begins. This feedback-based synchronization prevents overlapping of volume exchanges, eliminating gas trapping and CO2 rebreathing while maintaining high CO2 removal efficiency.
3Productivity
If baseline pressure is switched frequently to maintain ventilation, then ventilation efficiency is improved, but patient comfort decreases due to synchronized pressure changes with inspiration efforts
Solution Approach 1:
The patent applies dynamics by making the pressure level transition timing adaptive rather than fixed. The ventilator continuously monitors patient breathing efforts and dynamically adjusts the timing of baseline pressure switches based on detected inspiration efforts. The trigger time window and delay time parameters allow the system to adapt to varying patient breathing patterns, synchronizing pressure changes with patient physiology to improve comfort while maintaining ventilation efficiency.
4Reliability
If PEEP is increased to prevent alveolar collapse, then lung protection is improved, but peak pressure increases which can be harmful to the respiratory system
Solution Approach 1:
The patent segments the pressure support into two distinct levels: a first pressure level (higher PEEP) dedicated to lung protection and preventing alveolar collapse, and a second pressure level (lower PEEP) used for CO2 removal. By separating these functions into distinct pressure phases rather than using a single high PEEP level continuously, the system maintains lung protection benefits while reducing the time-averaged peak pressure exposure, thereby protecting the respiratory system from pressure-related harm.
Data Source
AI summary
A method for controlling mechanical lung ventilation is described. The method may include intermittently switching the airway pressure of a patient from a first baseline pressure level to a second baseline pressure and vice-versa such that the patient is able to breathe spontaneously in both first and second baseline pressure levels; detecting an inspiration effort by the patient within a predetermined period of time before a switching event of the intermittently switching the airway pressure; and controlling, responsive to detecting a breathing effort, a flow control valve and an exhalation valve to adjust a length of the first period of time according to a delay time so a patient inspiration-exhalation cycle is completed prior to the switching event.