When the blood flow regulator (7) is switched on, blood flows at 4 ml/min from the arterial cannula (1) through the flow through cell electrode assembly (5) to the waste bag (6). A cable (8) connects the lithium electrode to the computer (9). The voltage across the membrane of the electrode is recorded and converted to lithium concentration and is displayed on the screen. The lithium chloride solution is injected intravenously and after a delay due to the circulation time the lithium dilution curve is displayed. For more details see sensor and flow regulator.