Method for continuously measuring the haemoglobin concentration in an extracorporeal circulation

摘要

To measure the haemoglobin concentration, an amount of about 0.1 ml of blood per min is continuously taken under sterile conditions, and without altering the proportionate volume of the erythrocytes, from the extracorporeal circulation. A double peristaltic pump is used to dilute the blood in a fixed ratio. Blood and dilution medium are combined via a specially designed connector in order to avoid sedimentation of the erythrocytes. The erythrocytes are completely haemolysed by the dilution medium (0.5% NH3) and converted into oxyhaemoglobin. The haemolysate is homogenised in a stirred cell using a magnetic stirrer and is then transferred into a microcuvette in a photometer. The oxyhaemoglobin concentration is determined by measuring the extinction at a wavelength of 415 nm (SORET band). The method makes it possible to monitor the blood volume in an existing extracorporeal circulation, e.g. in artificial kidney treatment. It is also possible on the basis of this method to measure the concentration of other constituents of blood continuously over several hours.