Apparatus and method for the examination of a liquid medium

US4841974A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Walter Gumbrecht · Herzogenaurach, DE
• Wolfgang Schelter · Uttenreuth, DE
• Bernhard Montag · Schnaittach, DE
• Peter Hobel · Buckenhof, DE

Key dates

• Filing date: Dec 22, 1987
• Grant date: Jun 27, 1989
• Expiry date: Dec 22, 2007

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N33/49
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A measuring canal is provided which is connected to a catheter. The canal includes a measuring sensor and a reference sensor. The catheter includes several lumens that have a common opening to the liquid measuring medium. The flow direction of an infusion solution at the opening is reversible. A second lumen of the catheter is connected to the measuring canal which is provided with at least one measuring sensor and with at least one reference sensor as well as with a device for setting the outflow of the apparatus to a predetermined velocity. The flow of an infusion fluid and the liquid medium alternates in such a fashion that during a first time interval the measuring sensor is coupled to the liquid medium and the reference sensor is coupled to the infusion solution. In a second interval the situation is reversed so that the original measuring sensor is coupled to the infusion solution and the original reference sensor is connected to the liquid medium. The unique arrangement is effective for blood examination. Drift problems and toxicity problems cannot occur and no electrochemical reference electrode is required.