Digital Ventilator Gas Flow Control System
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Solution Overview
Problem
Low-flow mechanical ventilator systems can deliver hypoxic gases to patients even when minimum oxygen concentration settings are met, due to insufficient fresh gas flow rates, which may not meet individual patient oxygen requirements.
Innovation Solution
A system that includes a digital signal processor connected to a mixer and mechanical ventilator, calculating and controlling the fresh oxygen and total gas flow rates to ensure a predetermined oxygen concentration is maintained in the breathing circuit, using equations based on conservation of mass and patient metabolic needs, and providing feedback through a graphical display to prevent hypoxic gas delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If minimum oxygen concentration settings are maintained with mechanical linkages in low-flow mechanical ventilator operation, then the required minimum oxygen concentration for fresh gas flows is met, but hypoxic gases can still be delivered to the patient due to insufficient fresh gas flow rates
Solution Approach 1:
The patent replaces mechanical linkages with electronic controls and digital signal processing. The system uses a digital signal processor to receive ventilation parameter values, calculate fresh oxygen flow rates and total fresh gas flow rates, and control gas delivery electronically rather than through mechanical connections. This substitution eliminates the limitations of mechanical systems while maintaining oxygen concentration guarantees.
Solution Approach 2:
The patent implements a feedback control system where the digital signal processor continuously monitors ventilation parameters, calculates the actual fresh oxygen flow rate and total fresh gas flow rate, compares these values against safety thresholds, and adjusts gas delivery accordingly. The system provides visual feedback through displays showing calculated flow rates and oxygen concentrations, enabling real-time adjustment to prevent hypoxic gas delivery.
2Productivity
If low-flow mechanical ventilator operation is used to reduce gas consumption, then productivity is improved, but the risk of delivering hypoxic gases increases due to insufficient fresh gas flow rates
Solution Approach 1:
The system continuously monitors and calculates fresh oxygen flow rate and total fresh gas flow rate based on ventilation parameters, providing real-time feedback to ensure oxygen concentration remains above safety thresholds even during low-flow operation. The digital signal processor adjusts control signals to maintain safe oxygen levels while optimizing gas consumption.
Solution Approach 2:
The patent dynamically adjusts ventilation parameters including fresh oxygen flow rate, total fresh gas flow rate, and oxygen concentration based on patient needs and circuit conditions. The system calculates reference oxygen flow rates and compares actual values against these references, modifying operational parameters in real-time to prevent hypoxic delivery while maintaining efficient low-flow operation.
3Ease of operation
If mechanical linkages are used to maintain minimum oxygen concentration settings, then oxygen concentration control is simplified, but the system cannot adapt to individual patient oxygen requirements in low-flow conditions
Solution Approach 1:
The patent replaces fixed mechanical linkages with programmable electronic controls that can be adjusted for individual patient requirements. The digital signal processor receives ventilation parameter values specific to each patient and calculates appropriate fresh oxygen flow rates and concentrations dynamically, enabling customization while maintaining ease of operation through electronic interfaces.
Solution Approach 2:
The system transitions from static mechanical concentration control to dynamic electronic control that continuously calculates and adjusts oxygen flow rates based on real-time ventilation parameters. The digital signal processor adapts oxygen delivery to match individual patient metabolic needs and clinical conditions, allowing flexible adjustment without compromising operational simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents the delivery of hypoxic gases by dynamically adjusting gas flow rates to ensure adequate oxygen concentration, even in low-flow conditions, thereby ensuring safe respiratory support for patients.
Implementation Method 1
A vaporizer is pneumatically connected to the breathing circuit and to the mixer. The vaporizer receives at least the oxygen and the balance gas from the mixer and entrains anesthetic agent vapor into the received oxygen and balance gas.
Data Source
AI summary
A system for controlling the delivery of medical gases includes a digital signal processor that receives at least one ventilation parameter value change, calculates a fresh oxygen flow rate, total fresh gas flow rate into the breathing circuit, and a reference oxygen flow rate representative of a predetermined oxygen concentration delivered to a patient. A graphical display presents the calculated fresh oxygen flow rate, total fresh gas flow rate, and reference oxygen flow rate. A method of controlling the delivery of medical gases to a patient includes calculating a total fresh gas flow rate into the breathing circuit, calculating a fresh oxygen flow rate into the breathing circuit, calculating a reference oxygen flow rate representative of a predetermined oxygen concentration delivered to the patient and presenting the total fresh gas flow rate, the fresh oxygen flow rate, and reference oxygen flow rate on a graphical display.