Determination of patient blood volume at start of a dialysis treatment

Abstract

Embodiments of the disclosure provide a method for determining beginning blood volume of a patient during dialysis (e.g., hemodialysis). Ultrafiltration rates are determined at different time stamps during dialysis by obtaining a blood flowrate measurement and hematocrit measurements at input port and output port of a dialyzer connected to the patient. The flowrate and hematocrit measurements are used to determine fluid removed from the patient during dialysis. The ultrafiltration rates and fluid removed from the patient are used to determine the beginning blood volume of the patient.

1 . A method for determining beginning blood volume of a patient connected to a dialysis system, the method comprising:
 circulating, using a pump of the dialysis system, blood from the patient through a dialyzer; and   based on circulating the blood from the patient through the dialyzer, determining, using the dialysis system, the beginning blood volume of the patient using hematocrit values associated with an input side of the dialyzer, hematocrit values associated with an output side of the dialyzer, and a flowrate of blood through a first portion of tubing connecting the patient to the input of the dialyzer.   
     
     
         2 . The method according to  claim 1 , wherein determining the beginning blood volume further includes:
 displaying the beginning blood volume on a screen of the dialysis system.   
     
     
         3 . The method according to  claim 1 , wherein the flowrate of blood corresponding to the input side of the dialyzer is determined via a calibrated pumping rate of the pump or an input flowmeter of the dialysis system. 
     
     
         4 . The method of  claim 1 , wherein the hematocrit values associated with the input side of the dialyzer comprise hematocrit corresponding to the input side of the dialyzer at an initial time and hematocrit corresponding to the input side of the dialyzer after a first measurement period, wherein the hematocrit values associated with the output side of the dialyzer comprise hematocrit corresponding to the output side of the dialyzer at the initial time and hematocrit corresponding to the output side of the dialyzer after the first measurement period. 
     
     
         5 . The method according to  claim 4 , wherein hematocrit corresponding to the input side of the dialyzer and hematocrit corresponding to the output side of the dialyzer are measured via a first sensor assembly of the dialysis system and a second sensor assembly of the dialysis system, respectfully. 
     
     
         6 . The method according to  claim 4 , wherein hematocrit corresponding to the input side of the dialyzer is measured via a sensor assembly of the dialysis system, and after a time period, hematocrit corresponding to the output side of the dialyzer is measured via the sensor assembly of the dialysis system. 
     
     
         7 . The method of  claim 4 , wherein determining the beginning blood volume of the patient comprises:
 determining the flowrate of blood corresponding to the input side of the dialyzer;   determining a fluid removal rate at the initial time via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the output side of the dialyzer at the initial time;   determining a fluid removal rate after the first measurement period via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer after the first measurement period and the hematocrit corresponding to the output side of the dialyzer after the first measurement period;   determining volume of fluid removed for the first measurement period via the fluid removal rate at the initial time and the fluid removal rate after the first measurement period;   determining fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer after the first measurement period; and   determining the beginning blood volume via the fractional blood volume change and the volume of fluid removed for the first measurement period.   
     
     
         8 . The method according to  claim 7 , wherein determining the beginning blood volume further includes:
 determining whether there are more measurement periods; and   in response to the determining that there are more measurement periods, performing using the dialysis system:
 determining a fluid removal rate for a next measurement period via the flowrate of blood, hematocrit corresponding to the input side of the dialyzer after the next measurement period and hematocrit corresponding to the output side of the dialyzer after the next measurement period; 
 determining cumulative volume of fluid removed via two most recent fluid removal rates determined and volume of fluid removed for a previous measurement period; 
 determining the fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer for the next measurement period; and 
 determining the beginning blood volume via the fractional blood volume change and the cumulative volume of fluid removed. 
   
     
     
         9 . The method according to  claim 8 , wherein in response to the determining that there are more measurement periods, the dialysis system further performs:
 determining average beginning blood volume for all measurement periods; and   displaying the average of the multiple beginning blood volumes on a screen of the dialysis system.   
     
     
         10 . The method according to  claim 8 , wherein each measurement period has a duration of 1 minute. 
     
     
         11 . A non-transitory computer readable medium having processor-executable instructions stored thereon for determining beginning blood volume of a patient connected to a dialysis system, wherein the processor-executable instructions, when executed, facilitate:
 circulating, using a pump of the dialysis system, blood from the patient through a dialyzer; and   based on circulating the blood from the patient through the dialyzer, determining, using the dialysis system, the beginning blood volume of the patient using hematocrit values associated with an input side of the dialyzer, hematocrit values associated with an output side of the dialyzer, and a flowrate of blood through a first portion of tubing connecting the patient to the input of the dialyzer.   
     
     
         12 . The non-transitory computer readable medium according to  claim 11 , wherein determining the beginning blood volume further includes:
 displaying the beginning blood volume on a screen of the dialysis system.   
     
     
         13 . The non-transitory computer readable medium according to  claim 11 , wherein the hematocrit values associated with the input side of the dialyzer comprises hematocrit corresponding to the input side of the dialyzer at an initial time and hematocrit corresponding to the input side of the dialyzer after a first measurement period, wherein the hematocrit values associated with the output side of the dialyzer comprises hematocrit corresponding to the output side of the dialyzer at the initial time and hematocrit corresponding to the output side of the dialyzer after the first measurement period. 
     
     
         14 . The non-transitory computer readable medium according to  claim 13 , wherein determining the beginning blood volume of the patient comprises:
 determining the flowrate of blood corresponding to the input side of the dialyzer;   determining a fluid removal rate at the initial time via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the output side of the dialyzer at the initial time;   determining a fluid removal rate after the first measurement period via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer after the first measurement period and the hematocrit corresponding to the output side of the dialyzer after the first measurement period;   determining volume of fluid removed for the first measurement period via the fluid removal rate at the initial time and the fluid removal rate after the first measurement period;   determining fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer after the first measurement period; and   determining the beginning blood volume via the fractional blood volume change and the volume of fluid removed for the first measurement period.   
     
     
         15 . The non-transitory computer readable medium according to  claim 13 , wherein determining the beginning blood volume further includes:
 determining whether there are more measurement periods; and   in response to the determining that there are more measurement periods, performing using the dialysis system:
 determining a fluid removal rate for a next measurement period via the flowrate of blood, hematocrit corresponding to the input side of the dialyzer after the next measurement period and hematocrit corresponding to the output side of the dialyzer after the next measurement period; 
 determining cumulative volume of fluid removed via two most recent fluid removal rates determined and volume of fluid removed for a previous measurement period; 
 determining the fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer for the next measurement period; and 
 determining the beginning blood volume via the fractional blood volume change and the cumulative volume of fluid removed. 
   
     
     
         16 . The non-transitory computer readable medium according to  claim 15 , wherein in response to the determining that there are more measurement periods, the dialysis system further performs:
 determining average beginning blood volume for all measurement periods; and   displaying the average of the multiple beginning blood volumes on a screen of the dialysis system.   
     
     
         17 . An apparatus for determining beginning blood volume of a patient connected to a dialysis system, the apparatus comprising:
 a processor; and   a memory having processor-executable instructions stored thereon, wherein the processor-executable instructions, when executed by the processor, facilitate:
 circulating, using a pump of the dialysis system, blood from the patient through a dialyzer; and 
 based on circulating the blood from the patient through the dialyzer, determining, using the dialysis system, the beginning blood volume of the patient using hematocrit values associated with an input side of the dialyzer, hematocrit values associated with an output side of the dialyzer, and a flowrate of blood through a first portion of tubing connecting the patient to the input of the dialyzer. 
   
     
     
         18 . The apparatus of  claim 17 , wherein determining the beginning blood volume further includes:
 displaying the beginning blood volume on a screen of the dialysis system.   
     
     
         19 . The apparatus of  claim 17 , wherein the flowrate of blood corresponding to the input side of the dialyzer is determined via a calibrated pumping rate of the pump or an input flowmeter of the dialysis system. 
     
     
         20 . The apparatus of  claim 17 , wherein the hematocrit values associated with the input side of the dialyzer comprises hematocrit corresponding to the input side of the dialyzer at an initial time and hematocrit corresponding to the input side of the dialyzer after a first measurement period, wherein the hematocrit values associated with the output side of the dialyzer comprises hematocrit corresponding to the output side of the dialyzer at the initial time and hematocrit corresponding to the output side of the dialyzer after the first measurement period. 
     
     
         21 . The apparatus of  claim 20 , wherein determining the beginning blood volume of the patient comprises:
 determining the flowrate of blood corresponding to the input side of the dialyzer;   determining a fluid removal rate at the initial time via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the output side of the dialyzer at the initial time;   determining a fluid removal rate after the first measurement period via the flowrate of blood, the hematocrit corresponding to the input side of the dialyzer after the first measurement period and the hematocrit corresponding to the output side of the dialyzer after the first measurement period;   determining volume of fluid removed for the first measurement period via the fluid removal rate at the initial time and the fluid removal rate after the first measurement period;   determining fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer after the first measurement period; and   determining the beginning blood volume via the fractional blood volume change and the volume of fluid removed for the first measurement period.   
     
     
         22 . The apparatus of  claim 21 , wherein determining the beginning blood volume further includes:
 determining whether there are more measurement periods; and   in response to the determining that there are more measurement periods, performing using the dialysis system:
 determining a fluid removal rate for a next measurement period via the flowrate of blood, hematocrit corresponding to the input side of the dialyzer after the next measurement period and hematocrit corresponding to the output side of the dialyzer after the next measurement period; 
 determining cumulative volume of fluid removed via two most recent fluid removal rates determined and volume of fluid removed for a previous measurement period; 
 determining the fractional blood volume change via the hematocrit corresponding to the input side of the dialyzer at the initial time and the hematocrit corresponding to the input side of the dialyzer for the next measurement period; and 
 determining the beginning blood volume via the fractional blood volume change and the cumulative volume of fluid removed. 
   
     
     
         23 . The apparatus of  claim 22 , wherein in response to the determining that there are more measurement periods, the dialysis system further performs:
 determining average beginning blood volume for all measurement periods; and   displaying the average of the multiple beginning blood volumes on a screen of the dialysis system.