Closed-Loop Anesthesia Delivery Using BIS Feedback
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Solution Overview
Problem
Current anesthesia delivery systems lack efficient closed-loop control, reliability, and versatility in managing both intravenous and inhalational agents, and fail to account for cardiovascular drug effects on blood pressure and heart rate, leading to delays and human errors in anesthesia depth monitoring.
Innovation Solution
A microprocessor-based automatic anesthesia delivery system using Bispectral Index (BIS) and end-tidal concentrations of inhalational agents for closed-loop control, incorporating dual syringe pumps for intravenous and inhalational agents, with safety features to adjust drug delivery based on blood pressure, heart rate, and carbon dioxide levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual monitoring and adjustment of anesthesia delivery is used, then the system is simple and cost-effective, but it causes time delays and human errors in responding to changes in anesthesia depth
Solution Approach 1:
The patent implements a closed-loop feedback control system where the BIS monitor continuously measures anesthesia depth and feeds this information back to the syringe pump, which automatically adjusts drug delivery to maintain the target BIS value. This eliminates manual monitoring delays and human errors while maintaining system simplicity through automated feedback control.
2Manufacturing precision
If Target Controlled Infusion pumps are used for closed loop control, then anesthesia delivery precision is improved, but the cost increases 3-4 times compared to simple syringe pumps
Solution Approach 1:
The patent uses a simple, low-cost syringe pump with a basic on/off control algorithm instead of expensive Target Controlled Infusion pumps. The system achieves adequate drug delivery precision through frequent monitoring adjustments and automated feedback control, demonstrating that complex TCI pump mechanisms are not necessary for effective closed-loop anesthesia delivery.
3Measurement precision
If closed loop control is implemented using BIS and inhalational agent concentrations, then anesthesia depth control is improved, but the system complexity and cost increase
Solution Approach 1:
The patent merges the BIS monitor and inhalational agent concentration monitor into a unified closed-loop control system that simultaneously uses both parameters to guide drug delivery adjustments. This integration improves anesthesia depth control accuracy while managing system complexity through coordinated multi-parameter monitoring and a single syringe pump controller.
Solution Approach 2:
The syringe pump is designed to respond to multiple input parameters (BIS value and inhalational agent concentration) and perform a single universal function of adjusting intravenous drug delivery to achieve the target BIS, demonstrating multi-functionality that improves control precision without proportionally increasing complexity.
4Object-affected harmful factors
If safety features monitoring blood pressure and heart rate are incorporated, then patient safety is improved, but the device complexity increases
Solution Approach 1:
The patent incorporates preliminary safety checks by monitoring blood pressure and heart rate before and during drug delivery adjustments. The system preemptively prevents cardiovascular side effects by detecting adverse trends early and adjusting or stopping drug delivery before significant hemodynamic instability occurs, demonstrating preventive safety monitoring.
Data Source
Figure 1
AI summary
This invention relates to an improved automatic anaesthesia delivery system comprising a) At least one of a bispectral index monitor and an anaesthesia vital sign monitor interfaced with a computer to receive input from patient; b) At least one pump for controlling delivery of drug based on the feedback from patient; c) said computer having specific software for controlling said pump(s) and for fine tuning the dosage based on patient's response and requirements.