Blood Pump Work Estimation via Pressure-Volume Loop Analysis
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Solution Overview
Problem
Current methods for determining the work performed by a patient's heart and an implantable blood pump are invasive and impractical for monitoring outside a clinical or hospital setting, especially for patients with partial-assistance blood pumps where the transition from partial to full assistance can be undesirable.
Innovation Solution
A non-invasive method to estimate the work performed by a blood pump by calculating volume and differential pressure across the pump, using flow rate data points to determine the area enclosed by these values, which indicates the amount of work available for the pump, allowing for adjustments in motor speed to maintain optimal assistance to the heart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive catheter-based measurements are used to determine work performed by the heart and blood pump, then measurement precision is improved, but ease of operation deteriorates due to impracticality for monitoring outside clinical settings
Solution Approach 1:
The patent replaces invasive mechanical catheter-based measurements with a non-invasive computational method using flow rate data and pressure-volume loop analysis. The system calculates work performed by integrating pressure and volume changes derived from pump flow rate measurements, eliminating the need for physical catheters while maintaining measurement capability.
Solution Approach 2:
The patent introduces a computational model as an intermediary between the blood pump and the measurement process. By using the pump's flow rate data as input to calculate pressure-volume loops and work performed, the system creates an indirect but accurate measurement pathway that avoids direct invasive contact with the patient's cardiovascular system.
2Productivity
If the blood pump motor speed is increased to perform more work, then productivity is improved, but reliability deteriorates due to potential unwanted transitions from partial to full assistance
Solution Approach 1:
The patent implements a feedback mechanism where the calculated work performed by the heart and pump is continuously monitored and used to adjust pump motor speed. When the heart's work capacity is sufficient, the pump speed is reduced to maintain partial assistance mode, preventing unwanted transitions to full assistance while still providing necessary support.
Solution Approach 2:
The patent makes the pump's assistance level dynamic rather than fixed, allowing automatic adjustment between partial and full assistance modes based on real-time assessment of the heart's work capacity. This dynamic adaptation ensures the pump provides optimal support without over-assisting, maintaining reliability across varying physiological conditions.
Data Source
AI summary
A method of estimating an amount of work available to be performed by a blood pump implanted in a patient includes calculating a first coordinate value characterizing a volume of blood impelled in the pump and a second coordinate value characterizing a differential pressure across the pump for each of a plurality of flow rate data points of a given cardiac cycle of the patient, each flow rate data point indicative of a flow rate of blood through the pump. An area enclosed by the first and second coordinate values of the plurality of flow rate data points is determined, the determined area being indicative of an amount of work available to be performed by the blood pump.