Biological fluid flow control apparatus and method
First Claim
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1. A method for controlling flow through a biological fluid processing device fluid flow path into a living subject, comprising:
- flowing fluid through the fluid flow path at a flow rate;
repeatedly monitoring the pressure of fluid flowing in the fluid flow path relative to at least a low pressure level, an upper pressure level above the low pressure level and a maximum pressure level above the upper pressure level, the repeated monitoring being at a selected time interval between each monitoring cycle;
decreasing the fluid flow rate in the fluid flow path by a selected amount of decrease if the monitored pressure is continuously between the upper pressure level and the maximum pressure level for a certain amount of time greater than the selected time interval;
incrementally advancing a flow rate increase clock at each monitoring cycle if the monitored pressure is below the low pressure level and the fluid flow rate is at a desired rate;
increasing the flow rate of fluid in the fluid flow path by a selected amount of increase if the flow rate increase clock indicates that the monitored pressure has been continuously below the low pressure level for at least another amount of time greater than the selected time interval and, if so, restarting the flow rate increase clock;
restarting the flow rate increase clock if the monitored pressure is above the low pressure level, andleaving the fluid flow rate unchanged if the monitored pressure is between the low pressure level and the upper pressure level.
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Abstract
Apparatus, system and method are provided for controlling flow through a biological fluid processing device. Pressure of fluid flow through a flow path is monitored and flow rate in the flow path is increased or decreased based on sensed pressure levels for selected periods of time. This has particular application in controlling flow in an infusion or return flow path of an apheresis device that separates whole blood into one or more blood components.
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Citations
18 Claims
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1. A method for controlling flow through a biological fluid processing device fluid flow path into a living subject, comprising:
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flowing fluid through the fluid flow path at a flow rate; repeatedly monitoring the pressure of fluid flowing in the fluid flow path relative to at least a low pressure level, an upper pressure level above the low pressure level and a maximum pressure level above the upper pressure level, the repeated monitoring being at a selected time interval between each monitoring cycle; decreasing the fluid flow rate in the fluid flow path by a selected amount of decrease if the monitored pressure is continuously between the upper pressure level and the maximum pressure level for a certain amount of time greater than the selected time interval; incrementally advancing a flow rate increase clock at each monitoring cycle if the monitored pressure is below the low pressure level and the fluid flow rate is at a desired rate; increasing the flow rate of fluid in the fluid flow path by a selected amount of increase if the flow rate increase clock indicates that the monitored pressure has been continuously below the low pressure level for at least another amount of time greater than the selected time interval and, if so, restarting the flow rate increase clock; restarting the flow rate increase clock if the monitored pressure is above the low pressure level, and leaving the fluid flow rate unchanged if the monitored pressure is between the low pressure level and the upper pressure level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A durable biological fluid processing device for processing biological fluid in a disposable fluid processing flow circuit of the type including a fluid flow path for directing fluid flow from the processing circuit to a living subject, the device including a pump for pumping fluid through the fluid flow path, a pressure sensor for monitoring fluid pressure in the flow path and a controller cooperatively associated with the pump and the pressure sensor for controlling the flow rate and pressure of fluid flowing through the fluid flow path, wherein the controller is configured to, at least:
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repeatedly monitor the pressure of fluid flowing in the fluid flow path relative to at least a low pressure level, an upper pressure level above the low pressure level and a maximum pressure level above the upper pressure level, the repeated monitoring being at a selected time interval between each monitoring cycle; decrease the fluid flow rate in the fluid flow path by a selected amount of decrease if the monitored pressure is continuously between the upper pressure level and the maximum pressure level for a certain amount of time greater than the selected time interval; and leave the fluid flow rate unchanged if the monitored pressure is between the low pressure level and the upper pressure level; the controller including a flow rate increase clock operable to determine if another time period greater than the selected time interval has passed, the controller being further configured to (i) incrementally advance the flow rate increase clock at each monitoring cycle if the monitored pressure is below the low pressure level and the flow rate is at a desired rate, (ii) increase the fluid flow rate by a selected amount of flow rate increase if the flow rate increase clock indicates that the monitored pressure has been continuously below the low pressure low pressure level for at least the other time period and, if so, restart the flow rate increase clock, and (iii) restart the flow rate increase clock if the monitored pressure is above the low pressure level. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification