Blood filtration systems

Abstract

A blood filtration system can reduce the amount of plasma constituents (e.g., water and/or electrolytes) in the blood of the patient, and accordingly increase the hematocrit value of the patient. The blood filtration system (e.g., a controller, or the like) can determine a hematocrit value of a patient. The blood filtration system can determine a venous pressure of vasculature of a patient. The blood filtration system can compensate for pressure head in a component of a blood circuit (e.g., a withdrawal line of a catheter), for example to improve the accuracy of the venous pressure determination. The blood filtration system can determine one or more resistance characteristics of a blood circuit for the blood filtration system. The resistance characteristics can correspond to a resistance to a flow of blood through a component of the blood circuit.

1 - 63 . (canceled) 
     
     
         64 . A blood filtration system for reducing one or more plasma constituents in blood of a patient, the system comprising:
 a variable-speed blood pump configured to pump blood in a withdrawal line, through a filter, and into an infusion line, wherein:
 the withdrawal line and the infusion line are configured to couple with a catheter, and the catheter is configured for insertion into a blood stream of the patient; 
   a controller including processing circuitry, wherein the controller is configured to:
 determine a withdrawal line resistance characteristic of the withdrawal line using a first pressure sensor in communication with the withdrawal line to measure pressure in the withdrawal line, the withdrawal line resistance characteristic corresponding to an amount of resistance to a flow of blood through the withdrawal line, and wherein determining the withdrawal line resistance characteristic includes:
 determining a blood flow rate through the withdrawal line using at least one blood flow rate sensor; and 
 dividing the measured pressure in the withdrawal line by the blood flow rate through the withdrawal line; 
 
 determine an infusion line resistance characteristic of the infusion line using a second pressure sensor in communication with the infusion line to measure pressure in the infusion line, the infusion line resistance characteristic corresponding to an amount of resistance to a flow of blood through the infusion line; and 
 provide a notification of one or more of the withdrawal line resistance characteristic or the infusion line resistance characteristic. 
   
     
     
         65 . The blood filtration system of  claim 64 , wherein the controller is configured to:
 determine a hematocrit value of the patient;   determine a hemoconcentration resistance characteristic of the blood according to the determined hematocrit value of the patient, wherein the withdrawal line resistance characteristic or the infusion line resistance characteristic correspond in part to the hemoconcentration characteristic; and   determine an occlusion resistance characteristic by subtracting the hemoconcentration resistance characteristic from the withdrawal line resistance characteristic or from the infusion line resistance characteristic.   
     
     
         66 . The blood filtration system of  claim 65 , wherein the notification of the one or more of the withdrawal line resistance characteristic or the infusion line resistance characteristic includes the occlusion resistance characteristic. 
     
     
         67 . The blood filtration system of  claim 65 , wherein the controller is configured to provide a notification of the occlusion resistance characteristic. 
     
     
         68 . The blood filtration system of  claim 65 , wherein determining the hematocrit value of the patient includes:
 controlling the speed of the blood pump and setting a flow rate of blood through the filter at a first blood flow rate;   controlling the speed of the blood pump and setting the flow rate of blood through the filter at a second blood flow rate, wherein the first blood flow rate is different than the second blood flow rate; and   determining the hematocrit at the second blood flow rate.   
     
     
         69 . The blood filtration system of  claim 64 , wherein the controller is configured to:
 compare the infusion line resistance or the withdrawal line resistance to a resistance threshold;   reduce a filtration rate or increase the blood flow rate if the withdrawal line resistance or the infusion line resistance exceeds the resistance threshold.   
     
     
         70 . The blood filtration system of  claim 64 , wherein the withdrawal line and the infusion line are configured to be in communication with the filter, and the filter is configured to reduce an amount of one or more plasma constituents in blood flowing through the filter and provide a filtrate fluid including the plasma constituents. 
     
     
         71 . The system of  claim 70 , wherein the controller is further configured to:
 control the speed of a filtration pump to vary the extraction rate of the filtrate fluid from the filter;   vary the extraction rate from a first specified extraction rate;   wait for a specified time period;   monitor the withdrawal line resistance characteristic or the infusion line resistance characteristic; and   provide a notification if the infusion line resistance characteristic or the withdrawal line resistance characteristic increases after the specified time period.   
     
     
         72 . The system of  claim 70 , wherein the controller is configured to:
 vary a filtration rate for reducing the plasma constituents in the blood;   wait for a specified time period;   monitor the withdrawal line resistance or the infusion line resistance; and   operate a harvesting pump to extract filtrate fluid from a filtrate reservoir and inject the filtrate fluid into an inlet of the filter to dilute the blood flowing through the filter.   
     
     
         73 . The blood filtration system of  claim 64 , wherein the controller is configured to:
 determine a venous pressure of the patient by determining a pressure differential between the first pressure sensor and the second pressure sensor; and   provide a notification when the pressure differential exceeds a pressure differential threshold.   
     
     
         74 . The blood filtration system of  claim 73 , wherein determining the venous pressure of the patient includes compensating for a pressure head in the withdrawal line. 
     
     
         75 . The blood filtration system of  claim 74 , further comprising a first pressure sensor in communication with the withdrawal line and configured to measure the pressure in the withdrawal line, wherein the first pressure sensor is located remote from a catheter tip of the withdrawal line, and the controller is configured to determine the venous pressure of the patient at the catheter tip by compensating for the pressure head in the withdrawal line between the catheter tip and the first pressure sensor. 
     
     
         76 . The blood filtration system of  claim 64 , wherein determining the infusion line resistance characteristic includes:
 determining a blood flow rate through the withdrawal line using at least one blood flow rate sensor; and   dividing the measured pressure in the withdrawal line by the blood flow rate through the withdrawal line.