Anesthesia Pneumatic System Tidal Volume Control
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Solution Overview
Problem
Anesthesia devices with radial compressors face challenges in delivering small tidal volumes, leading to oscillating volumes in the pneumatic system, which results in patients receiving insufficient fresh oxygen and rebreathing exhaled gases, especially during low-flow anesthesia, limiting their use in pediatric patients and increasing anesthetic gas consumption and environmental release.
Innovation Solution
A pneumatic system with a control unit, radial compressor, carbon dioxide absorber, and flush valve assembly that measures and adjusts tidal volumes using sensors to prevent oscillating volumes by switching between closed and open anesthesia modes, ensuring reliable delivery of fresh gas and scavenging of exhaled gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a radial compressor is used in a closed anesthesia system, then the system can operate with small tidal volumes and allow bidirectional gas flow, but oscillating volumes occur leading to insufficient fresh oxygen delivery and rebreathing of exhaled gases
Solution Approach 1:
The control unit continuously monitors the tidal volume delivered to the patient and compares it with the set tidal volume. When oscillating volumes are detected (delivered tidal volume significantly differs from set tidal volume), the control unit automatically opens the flush valve to introduce fresh gas into the system, thereby preventing insufficient oxygen delivery and rebreathing of exhaled gases.
Solution Approach 2:
The flush valve assembly acts as an intermediary component that introduces fresh gas into the pneumatic system when oscillating volumes occur. This intermediary mechanism prevents the direct negative effect of oscillating volumes on patient oxygenation by adding fresh gas between the compressor and the patient circuit.
2Loss of substance
If fresh gas flow is reduced during stable anesthesia phases, then anesthetic gas consumption is reduced, but oscillating volumes occur causing patients to rebreath exhaled gases
Solution Approach 1:
The control unit monitors tidal volume delivery and triggers the flush valve to open when oscillating volumes are detected, regardless of the overall fresh gas flow setting. This feedback mechanism ensures that even during low fresh gas flow modes, patients do not rebreath exhaled gases when oscillations occur.
Solution Approach 2:
The system proactively prevents rebreathing by detecting oscillating volumes before they become harmful and automatically introducing fresh gas through the flush valve. This preliminary anti-action counteracts the potential harmful effect of rebreathing before it significantly impacts the patient.
3Reliability
If the flush valve is continuously open to prevent oscillating volumes, then fresh oxygen delivery is reliable, but anesthetic gas consumption and environmental release increase
Solution Approach 1:
The flush valve is controlled by a feedback mechanism that opens it only when oscillating volumes are detected and closes it when normal operation is restored. This on-demand operation ensures reliable oxygen delivery when needed while minimizing unnecessary fresh gas flow and anesthetic gas consumption during stable periods.
Solution Approach 2:
The flush valve transitions from a static continuously-open state to a dynamic on-demand state, opening and closing based on real-time monitoring of tidal volume delivery. This dynamic control optimizes the balance between ensuring reliable oxygen delivery and minimizing anesthetic gas consumption.
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
Enables safe and efficient anesthesia delivery with small tidal volumes, preventing rebreathing of carbon dioxide-depleted gases and reducing anesthetic gas consumption and environmental release, making the system suitable for various patient groups including infants and children.
Implementation Method 1
A radial compressor draws in an anesthetic gas, formulated as a mixture of oxygen or air with nitrous oxide and evaporated anesthetic from a so-called fresh gas line
Implementation Method 2
The exhaled carbon dioxide is absorbed by breathing lime
Implementation Method 3
As soon as the pressure conditions reverse, i.e., as soon as a pressure level in the lungs of the patient is above the pressure level at the radial compressor, the gas flows from the patient through an expiratory nonreturn valve and through the radial compressor
Data Source
AI summary
A pneumatic system (55) for an anesthesia system, includes an internal closed-circuit system (34) and with an external closed-circuit system (54). The internal closed-circuit system (34) has a flush valve assembly (49). The flush valve assembly (49) can be brought into an open state by a control unit (200) on the basis of a current tidal volume.