Patient Support Bladder Pressure Control With Adaptive Delay
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Solution Overview
Problem
Existing patient support systems with pressurized bladders lack effective regulation of fluid pressure, leading to inadequate pressure relief and potential for pressure ulcers, as they fail to adjust pressure dynamically in response to patient weight and position changes.
Innovation Solution
A programmable pressure control assembly that monitors fluid pressure in multiple bladders, adjusts pressure based on predefined acceptable ranges, and employs algorithms to determine adjustment timing, incorporating a compressor and valves to maintain optimal pressure levels, with features like sleep mode and weight-sensing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous pressure monitoring and adjustment is implemented, then pressure relief effectiveness is improved, but device complexity increases
Solution Approach 1:
The system dynamically adjusts the delay period based on the magnitude of pressure deviation from the therapeutic range. When pressure deviates significantly, a shorter delay period enables faster response. When pressure is only slightly out of range or fluctuating near boundaries, a longer delay period prevents unnecessary adjustments. This dynamic adaptation resolves the contradiction by making the system responsive when needed while remaining stable when not needed.
Solution Approach 2:
The controller changes the time delay parameter based on the sensed pressure values and their relationship to the therapeutic range. The system evaluates whether pressure values are above, below, or within the therapeutic range and adjusts the delay period accordingly. This parameter change strategy allows the system to balance between rapid pressure correction and avoidance of spurious adjustments, resolving the contradiction between reliability and complexity.
2Speed
If pressure adjustment is initiated immediately when pressure leaves acceptable range, then pressure regulation responsiveness is improved, but false adjustments due to transient fluctuations increase
Solution Approach 1:
The system implements a preliminary delay period before initiating pressure adjustment when pressure leaves the acceptable range. This delay allows transient fluctuations to settle and determines whether the pressure deviation is sustained or temporary. The delay period is not fixed but adapts based on the nature of the deviation, providing preliminary assessment before taking corrective action. This resolves the contradiction by filtering out false adjustments while maintaining responsiveness to genuine pressure issues.
3Adaptability or versatility
If multiple algorithms are used to determine delay period, then adaptability to different pressure conditions is improved, but device complexity increases
Solution Approach 1:
The controller applies different delay period strategies based on the local pressure condition. When pressure is above the therapeutic range, one delay calculation method is used. When pressure is below the range, a different method is applied. When pressure fluctuates near boundaries, yet another approach is taken. This local quality approach allows the system to be highly adaptive to specific pressure conditions while keeping the overall control logic manageable through clear conditional branching.
4Reliability
If pressure monitoring is continuously active, then pressure ulcer prevention is improved, but energy consumption increases
Solution Approach 1:
The system uses periodic pressure sampling rather than truly continuous monitoring. The controller monitors pressure at regular intervals and only initiates adjustment sequences when pressure values fall outside the therapeutic range. The delay period mechanism further reduces unnecessary adjustments by waiting to see if transient fluctuations resolve themselves. This periodic action with conditional triggering maintains pressure ulcer prevention while significantly reducing energy consumption compared to continuous active adjustment.
Data Source
AI summary
An apparatus for supporting a patient, such as a hospital bed, is provided. The apparatus includes a patient support surface and at least one fluid containing bladder. A pressure control assembly is operably coupled with the bladder. When the fluid pressure within the bladder falls outside of an acceptable range of pressure values, the active adjustment of the pressure within the bladder is initiated by the pressure control assembly if the pressure does not return to the acceptable range of pressure values within a time period, e.g., a time delay, that has a variable length.