Air Mattress Bladder Control Using Pressure-Change Feedback
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Solution Overview
Problem
Prolonged exposure to excessive pressure and skin shear on inflatable patient support surfaces can lead to the formation of pressure ulcers, as existing systems fail to effectively manage pressure distribution and adapt to changes in patient position.
Innovation Solution
A control system comprising a source of pressurized air, valves, pressure sensors, and a processor-controlled controller that monitors pressure changes and adjusts the inflation/deflation of inflatable bladders to maintain a target pressure within a tolerance range, determining patient position and making adjustments based on weight and articulation of the patient support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the bladder is inflated to a fixed target pressure, then the pressure control is simple, but the system cannot adapt to changes in patient position and weight
Solution Approach 1:
The system continuously monitors pressure changes in real-time and uses this feedback to dynamically adjust bladder inflation. The processor detects rate of pressure change and compares it against threshold values to determine patient presence and position, then automatically adjusts target pressures accordingly, enabling adaptation without manual intervention
Solution Approach 2:
The system transitions from static fixed-pressure control to dynamic adaptive control. Target pressures are no longer constant but vary based on real-time patient position detection. The system dynamically adjusts inflation parameters based on detected patient movements, weight changes, and position transitions between sitting and lying states
2Reliability
If the system continuously monitors and adjusts pressure, then pressure management is optimized, but energy consumption increases
Solution Approach 1:
The system uses periodic monitoring at controlled intervals rather than continuous monitoring. Pressure changes are monitored at specific rates, and adjustments are made in periodic cycles. The system allows pressure to vary within tolerance ranges between adjustment cycles, reducing energy consumption while maintaining effective pressure management
Solution Approach 2:
The system changes operational parameters dynamically based on patient needs. Monitoring intensity and adjustment frequency are varied according to detected patient activity and position changes. During stable periods, the system reduces monitoring and adjustment frequency to conserve energy, while increasing activity during periods of patient movement or position change
3Loss of energy
If the system allows pressure to vary within a tolerance range, then energy consumption is reduced, but pressure control precision decreases
Solution Approach 1:
The system applies partial action by making adjustments only when necessary, rather than maintaining constant precision control. Pressure is allowed to vary within tolerance ranges, and the system intervenes with precise adjustments only when pressure approaches boundary conditions or patient position changes require re calibration
Solution Approach 2:
The system performs preliminary monitoring and detection before making adjustments. It establishes tolerance ranges in advance and monitors pressure trends to predict when adjustments will be needed. This allows the system to maintain energy efficiency while ensuring precision is restored before critical pressure deviations occur
4Reliability
If multiple bladders are used to improve pressure distribution, then pressure management effectiveness increases, but device complexity increases
Solution Approach 1:
The support surface is divided into multiple independent bladder zones that can be controlled separately. Each bladder or group of bladders can be independently inflated or deflated based on local patient needs detected by pressure sensors. This segmentation allows targeted pressure management in different body regions (head, torso, legs, heels) without requiring complex centralized control of all bladders simultaneously
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 manages pressure distribution, reducing the risk of pressure ulcers by automatically adjusting bladder pressure in response to patient movements and weight changes, maintaining optimal interface pressure and preventing prolonged exposure to excessive pressure.
Implementation Method 1
a pressure sensor in fluid communication with the first bladder and produce a first pressure signal indicative of air pressure within the first bladder
Data Source
AI summary
A patient support (10, 14) includes a source of pressurized air (64), a bladder (30), a valve (66) in fluid communication with the source of pressurized air (64) and to the bladder (30), a pressure sensor (28) in fluid communication with the bladder (30), and a controller (26) responsive to a pressure signal from the pressure sensor (28). The controller (26) may determine a rate of change of pressure within the bladder (30) and may store historical pressure data.