Method and apparatus for testing blood glucose in a reversible infusion line

A method of automatically and periodically measuring the blood glucose level of a patient wherein a patient is continuously receiving intravenous fluids through an infusion line and through a catheter inserted into a blood vessel in said patient's body, wherein a reversible peristaltic pump operates either forwardly to pump fluid into the patient's body or backwardly to draw blood from said patient's blood vessel catheter, and wherein said infusion line runs through a testing unit attached to said patient's body, comprising the steps:

• reversing said peristaltic pump periodically to pump a blood sample from said patient's blood vessel catheter into said testing unit,
• directing said blood sample into a side channel of said testing unit which houses a blood glucose test chamber,
• temporarily blocking the fluid communication between said test chamber and other fluid channels of said testing unit to isolate said blood sample in said test chamber, and
• measuring the blood glucose level of said patient's blood in said test chamber with an enzyme based glucose electrode.

An apparatus for automatically and periodically measuring a patient's blood glucose level comprising:

• a testing unit,
• infusion lines to connect said testing unit to a source of infusion fluid and to a catheter placed in a patient's blood vessel,
• reversible peristaltic pump means to move infusion fluid or blood either forwardly through said testing unit into said blood vessel catheter or backwardly into said testing unit and said infusion line,
• a main channel for blood or infusion fluid within said testing unit,
• a test chamber within said main channel for glucose testing, and
• valve means for controlling fluid flow through said main channel and isolating said test chamber.