Compression Therapy Monitoring via Photoplethysmographic Refill Time
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Solution Overview
Problem
Current compression therapy effectiveness is indirectly checked through pressure measurements, and the required pressure values can vary between patients, making it difficult to ensure direct and consistent therapeutic efficacy and safety.
Innovation Solution
A system combining compression means with a photoplethysmographic sensor and a computer that determines refill time after patient movement, alerting for insufficient or excessive refill times, allowing for direct assessment of therapy effectiveness and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If pressure sensors are used to monitor compression therapy, then the monitoring capability is improved, but the measurement precision of therapy effectiveness deteriorates because pressure values only indirectly indicate effectiveness and vary between patients
Solution Approach 1:
The patent replaces mechanical pressure sensors with a photoplethysmographic (PPG) sensor that uses optical methods to measure blood volume changes in the lower leg. This substitution allows direct measurement of venous refill time, providing precise information about compression therapy effectiveness without relying on indirect pressure measurements that vary between patients.
Solution Approach 2:
The patent changes the measurement parameter from compression pressure to venous refill time. By measuring how long it takes for veins to refill with blood after compression, the system directly assesses compression therapy effectiveness. This parameter change eliminates the need for patient-specific pressure calibration and provides a standardized, precise measurement of therapeutic effect.
2Ease of operation
If pressure measurements are used to verify compression therapy, then the monitoring process is simplified, but the reliability of therapy verification deteriorates because pressure values require patient-specific adjustments
Solution Approach 1:
The patent implements a universal measurement approach using PPG that works consistently across all patients without requiring individual calibration. The venous refill time measurement provides a standardized metric that reliably verifies compression therapy effectiveness for every patient, eliminating the need for patient-specific pressure adjustments while maintaining ease of operation.
Solution Approach 2:
The system provides direct feedback about compression therapy effectiveness through venous refill time measurements. The computer processes PPG data to determine whether compression is adequate, providing reliable verification that works uniformly for all patients. This feedback mechanism improves reliability by using a physiological response metric that directly reflects therapy effectiveness rather than relying on indirect pressure readings.
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 direct and easy monitoring of compression therapy effectiveness, improving patient outcomes by ensuring appropriate compression levels are maintained, thereby enhancing therapeutic efficacy and safety.
Implementation Method 1
Photoplethysmography is a diagnostic method used for venous insufficiency... Technically, photoplethysmography uses an infrared sensor (IR sensor) to determine the refilling time. The infrared sensor illuminates a spot on the patient's lower leg with infrared light, which is then reflected back to the sensor with varying intensity depending on the amount of blood in the veins.
Data Source
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AI summary
A system for compression therapy comprises a compression agent, a photoplethysmographic sensor (3), and a computer. Measurement values from the photoplethysmographic sensor (3) can be transmitted to the computer. The computer further comprises means for executing a procedure for monitoring the compression therapy, the procedure comprising the following steps: i. Receiving measurement values from the photoplethysmographic sensor (3) during compression therapy, ii. Determining a refill time based on the received measurement values from the photoplethysmographic sensor (3), iii. Checking whether the determined refill time falls below a predetermined lower limit, iv. optionally, issuing an alarm if the check reveals that the predetermined lower limit is not met.