Systems and methods for determining free plasma hemoglobin

A method of calculating the amount of free plasma hemoglobin in a concentrated fluid separated from a plasma-containing fluid, comprising:

• separating a plasma-containing fluid into separated plasma and a concentrated fluid;
• optically monitoring at least a portion of the separated plasma;
• generating an output indicative of the concentration of free plasma hemoglobin in said at least a portion of the separated plasma;
• calculating the amount of free plasma hemoglobin in at least a portion of the concentrated fluid based at least in part on said output;
• operating a pump to deliver at least a portion of the concentrated fluid to a fluid recipient;
• and
• generating an alarm or alert signal when the amount of free plasma hemoglobin in the concentrated fluid delivered to and/or to be delivered to the fluid recipient meets or exceeds a preselected or predetermined value.

A fluid separation system for separating a plasma-containing fluid into separated plasma and a concentrated fluid, the fluid separation system being configured to cooperate with a fluid flow circuit including a fluid separation chamber and a plasma outlet line associated with the fluid separation chamber for removing separated plasma from the fluid separation chamber, the fluid separation system comprising:

• an optical sensor assembly configured to monitor the contents of the plasma outlet line and produce an output indicative of the concentration of free plasma hemoglobin in the plasma outlet line;
• and
• a controller programmed to calculate the free plasma hemoglobin concentration of the contents of the plasma outlet line based at least in part on the output of the optical sensor assembly, wherein the controller includes a pre-programmed reference equation having one or more constants and representing an experimentally determined relationship between the output of the optical sensor assembly and free plasma hemoglobin concentration and is further programmed to, during a calibration test,
• generate an equation having one or more constants and representing the actual relationship between the output of the optical sensor assembly and free plasma hemoglobin concentration,
• compare at least one of the one or more constants of the pre-programmed reference equation to the corresponding constant or constants of the generated equation,
• register the optical sensor assembly as having passed the calibration test if the differences between the at least one of the one or more constants of the generated equation are less than a predetermined tolerance away from the corresponding constant or constants of the pre-programmed reference equation, and
• register the optical sensor assembly as having failed the calibration test if the differences between the at least one of the one or more constants of the generated equation are greater than a predetermined tolerance away from the corresponding constant or constants of the pre-programmed reference equation.

A method of calibrating an optical sensor assembly configured to monitor a fluid for the presence of free plasma hemoglobin, comprising:

• providing at least one fluid having a known free plasma hemoglobin concentration or at least one material having optical properties that are generally representative of the optical properties of a corresponding fluid having a known free plasma hemoglobin concentration;
• optically monitoring the at least one fluid or material using the optical sensor assembly;
• generating an output from the optical sensor assembly, with the output being indicative of the concentration of free plasma hemoglobin in the at least one fluid or said corresponding fluid;
• generating an equation using the output from the optical sensor assembly, with the equation having one or more constants and representing the actual relationship between the output of the optical sensor assembly and the concentration of free plasma hemoglobin in the at least one fluid or said corresponding fluid;
• comparing at least one of the one or more constants of the generated equation to the corresponding constant or constants of a reference equation having one or more constants and representing an experimentally determined relationship between the output of the optical sensor assembly and free plasma hemoglobin concentration;
• registering the optical sensor assembly as having passed the calibration test if the differences between the at least one of the one or more constants of the generated equation are less than a predetermined tolerance away from the corresponding constant or constants of the reference equation;
• and
• registering the optical sensor assembly as having failed the calibration test if the differences between the at least one of the one or more constants of the generated equation are greater than a predetermined tolerance away from the corresponding constant or constants of the reference equation.