Blood treatment systems and methods

A method for detecting blood in a dialysate circuit of a dialysis system, comprising:

• substantially filling with a first fluid a first portion of a chamber having a movable membrane separating the first portion of the chamber from a second portion of the chamber;
• using a light emitter and a light detector on opposed sides of the chamber to transmit light through the first portion of the chamber and measure a first light level for light transmitted through the first fluid in the first portion;
• emptying the first portion of the chamber as the second portion of the chamber is substantially filled with a second fluid;
• using the light emitter and the light detector to transmit light through the second portion of the chamber and measure a second light level for light transmitted through the second fluid in the second portion;
• and
• determining a presence of blood in the first fluid in the first portion by comparing the first and second light levels.

A method for detecting blood in a dialysate circuit of a dialysis system, comprising:

• providing a chamber having a movable membrane that fluidically separates a first portion of the chamber from a second portion of the chamber;
• providing used dialysate received from a dialyzer into the first portion of the chamber;
• using a light emitter and a light detector on opposed sides of the chamber to measure a characteristic of the used dialysate in the first portion;
• providing clean dialysate into the second portion of the chamber, thereby substantially emptying the first portion of the used dialysate;
• using the light emitter and the light detector on opposed sides of the chamber to measure a characteristic of the clean dialysate;
• and
• determining whether blood is present in the used dialysate in the first portion based on a comparison between the measured characteristic of the used dialysate in the first portion and the measured characteristic of the clean dialysate in the second portion.

A method for detecting blood in a dialysate circuit of a dialysis system, comprising:

• providing a blood leak sensor positioned to detect a characteristic of fluid in a chamber having a membrane that separates a first portion of the chamber from a second portion of the chamber, the blood leak sensor including a light emitter arranged to emit light into the chamber, and a light detector arranged to detect light emitted by the light emitter, and the light detector and light emitter being arranged such that a straight line path from the light emitter to the light detector passes through the chamber;
• using the blood leak sensor to detect a characteristic of clean dialysate in the second portion of the chamber;
• using the blood leak sensor to detect a characteristic of used dialysate, received from a dialyzer, in the first portion of the chamber;
• and
• using the detected characteristic of clean dialysate and the detected characteristic of the used dialysate to determine whether blood is present in the used dialysate.

A method for detecting blood in a dialysate circuit of a dialysis system, comprising:

• operating the dialysis system to provide dialysis treatment to a patient by, at least in part, circulating dialysate through a dialysate circuit including a balancing chamber and a dialyzer;
• providing a blood leak sensor arranged to determine a presence of blood in used dialysate flowing from the dialyzer to the balancing chamber, the blood leak sensor including a light emitter arranged to emit light into the balancing chamber, and a light detector arranged to detect light emitted by the light emitter, and the light detector and light emitter being arranged such that a straight line path from the light emitter to the light detector passes through the balancing chamber;
• and
• using the blood leak sensor to measure a characteristic of clean dialysate while the clean dialysate is in the balancing chamber and to measure a characteristic of used dialysate while the used dialysate is in the balancing chamber.