Determining conditions in centrifuged blood using measured pressure

Abstract

A method for determining a condition in a blood sample includes: providing a sample of blood; providing a metering probe having a pump for aspirating and dispensing; inserting the metering probe a selected distance into the blood sample; measuring the pressure between the sample and pump during sample aspiration or sample dispense; comparing the measured pressure with a reference value; and signaling the presence or absence of the condition. A method for confirming or detecting the presence of a selected layer of blood component in a centrifuged blood sample includes: measuring a pressure of a suspected selected layer in a metering probe during aspiration or dispense; comparing the measured pressure with a reference value, wherein if the measured pressure and the reference value are substantially identical then the selected layer of the blood component is confirmed. In a preferred embodiment the reference value is a pre-selected pressure range.

1 . A method for confirming or detecting the presence of a selected layer of blood component in a centrifuged blood sample, comprising:
 measuring a pressure of a suspected selected layer in a metering probe during aspiration or dispense;   comparing the measured pressure with a reference value, wherein if the measured pressure and the reference value are substantially identical then the selected layer of the blood component is confirmed.   
     
     
         2 . The method as claimed in  claim 1 , wherein the reference value is a pre-selected pressure range. 
     
     
         3 . The method as claimed in  claim 2 , wherein if the pressure falls within outside the pre-determined pressure range, then an alarm is sounded. 
     
     
         4 . The method as claimed in  claim 1 , wherein the pressure measurement is a first pressure profile and further comprising providing a second pressure profile as the reference value, wherein the second pressure profile is a measured pressure profile of the same or different layer of blood component in a different sample, or the second pressure profile is of a different layer of blood in the same sample, and wherein the second pressure profile may be measured before or after the first pressure profile; and
 comparing the first pressure profile with the second pressure profile, wherein if the first and second pressure profiles are substantially identical and the second profile is of the same component, then the selected layer of the blood component is confirmed, or wherein if the first and second pressure profile are significantly different and the second profile is of a different component, then the selected layer of the blood component is confirmed.   
     
     
         5 . The method as claimed in  claim 4 , wherein the selected layer is packed red blood cells and the different layer is plasma. 
     
     
         6 . The method as claimed in  claim 4 , wherein the first pressure profile is measured while the suspected selected layer is being aspirated. 
     
     
         7 . The method as claimed in  claim 4 , wherein the first pressure profile is measured while the suspected selected layer is being dispensed. 
     
     
         8 . The method as claimed in  claim 1 , wherein the selected layer is packed red blood cells and an additional layer is plasma and further comprising:
 moving a probe tip of the metering probe and centrifuged blood sample relative to one another to position the metering probe above the centrifuged blood sample;   moving the metering probe and sample relative to one another to bring the metering probe towards the surface of the blood sample;   detecting the surface of the sample;   aspirating plasma from the plasma layer of the sample;   measuring pressure while aspirating the plasma layer;   comparing a reference value and the measured pressure to confirm the additional layer is plasma;   moving the aspirating metering probe tip into the suspected packed red blood cells layer of the sample;   aspirating the suspected layer and measuring the pressure; and   comparing a reference value and the measured pressure to confirm the aspirated suspected layer is the selected packed red blood cells layer.   
     
     
         9 . The method as claimed in  claim 8 , further comprising dispensing the aspirated plasma before aspirating the packed red blood cells layer. 
     
     
         10 . The method as claimed in  claim 8 , further comprising determining the percentage of hematocrit in the sample by determining the height of the sample and the height of the packed red blood cells portion of the sample and then dividing the determined height of the confirmed red blood cells portion by the determined total height of the centrifuged sample. 
     
     
         11 . A method for determining a hematocrit level in a centrifuged blood sample, comprising:
 measuring a pressure of a suspected layer in a metering probe during aspiration or dispense;   comparing the measured pressure with a reference value, wherein if the measured pressure and the reference value are substantially identical then the selected layer of the blood component is confirmed wherein the selected layer is packed red blood cells and an additional layer is plasma and further comprising:   moving a probe tip of the metering probe and centrifuged blood sample relative to one another to position the metering probe above the centrifuged blood sample;   moving the metering probe and sample relative to one another to bring the metering probe towards the surface of the blood sample;   detecting the surface of the sample;   aspirating plasma from the plasma layer of the sample;   measuring pressure while aspirating the plasma layer;   comparing a reference value and the measured pressure to confirm the additional layer is plasma;   moving the aspirating metering probe tip into the suspected packed red blood cells layer of the sample;   aspirating the suspected layer and measuring the pressure;   comparing a reference value and the measured pressure to confirm the aspirated suspected layer is the selected packed red blood cells layer; and   determining the percentage of hematocrit in the sample by determining the height of the sample and the height of the packed red blood cells portion of the sample and then dividing the determined height of the confirmed red blood cells portion by the determined total height of the centrifuged blood sample.